UC-NRLF C E bflM fiSD m :.:>** m, UNIVERSnYgfCALIFORNIA COLLEGE of MINING DEPARTMENTAL LIBRARY BEQUEST OF SAMUELBENEDICTCHRISTY PROFESSOR OF MINING AND METALLURGY 1885-1914 ''tt^~ *> / of % |ftustum of Comparattbe AT HARVAKD COLLEGE. VOL. XI. PART I. LITHOLOGICAL STUDIES. A DESCRIPTION AND CLASSIFICATION OF THE ROCKS OF THE CORDILLERAS. BY M. E. WADSWORTH. ii WITH EIGHT PLATES. CAMBRIDGE: far tlje ffluscum. OCTOBER, 1884. INTRODUCTORY NOTE. I'MIKK the title of " Litliological Studies," ^a work is here presented to the public which is, in point of fact, a continuation of the publications of the Geological Survey of California, begun under my direction, in I860. Had that Survey been completed, the investigation of the rocks of the State would naturally have been one of the matters to which our attention would, at the proper time, have been turned; and, after the stoppage of the Survey, in planning for the elaboration of tin- materials in my hands, I, in 1877, determined that the lithological collections which I had accumulated, and which repre- sented a wide area, should be described and classified. For this purpose Dr. Wadsworth was selected ; and, a portion of his results being now ready, it is thought best that it should be published, without waiting for the completion of the entire work. It will undoubt- edly seem to the reader that what is here furnished does not exactly correspond with or carry out the idea suggested on the title-page, namely, that this is a description and classification of the rocks of the Cordilleras. The reason is this : Dr. Wadsworth having been led by his investigations to place his work on a considerably different basis from that built upon by other lithologists, has found it desirable, and indeed necessary, to incorporate in it results obtained from the study of material not furnished by the Cor- dilleran collect ions. In the portion of the work herewith offered to the public, rocks more basic than the basalts are brought under consideration ; and in doing this, it has been found that it was not possible to arrive at the end sought to be gained without using the materials furnished by other regions and by other lithologists. Should this investigation be continued and completed as it is hoped will be the case, a large amount of work having been already done with that end in view the Cordilleran collections will yield the chief portion of the material drawn upon for the remaining portion of the volume, so that it will be found that the work is essentially based on the collections made on tin- western side of the North American continent, the study of which gave rise to the ideas presented in this first part. J. D. \VH1TM.V ( '.\Mimii><,i:. MASS.. ( Muln-r 1*. 1884. vi CONTEXTS. origin of rocks demanded by the results of petrographical study, 10. The asso- ciations of different rocks, and the difficulties in their separation, 10, 11. 'Iho microscopic and field evidence the only means of distinction, 10, 11. Eruptive and Sedimentary Rocks resemble each other through the alteration of both, 11. Sedi- mentary Eocks presenting peculiar and abnormal conditions not proper guides, 11, 12. Sedimentary Rocks found not to present the microscopic characters of Erup- tive ones, 12. Requirements necessary to prove the passage of a Sedimentary into an Eruptive Hock, 12. Generally positive evidence that such passage does not exist can be obtained, 12, 13. The chemical resemblance of Sedimentary and Eruptive Rocks owing to the derivation of the former from the latter, 13. Minerals in Lavas of prior origin to the consolidation of the magma, 13 ; not de- rived from Sedimentary Rocks and characteristic of ancient and modern Eruptives, 13, 14. Field and microscopic evidence opposed to the theory of the derivation of Eruptive from Sedimentary Rocks, 14; the demands of that theory, 14. Vol- canic or eruptive action began in the earliest ages of the Earth, 14 ; this action, although intermittent, is a dying one, 14, 15. The older Eruptives the same, origi- nally, as the modern ones, 15 ; their present differences due to alteration, etc., 15. Under like conditions alteration is proportional to the age, 15. The presence of fragments of one rock in another is alone no proof of difference in geological age, 15. The alteration produced by internal molecular or chemical changes in the rock mass not to be confounded with superficial weathering, 15. Metamorpliism not extended Pseudomorphism, 15. Pseudomorphism but an incidental phase in alteration, 15. The explanation of changes in rocks, 15, 16. Metamorphisrn inversely proportional to the contained silica in the original rock, when time and other conditions are the same, 16. Eruptive Action, including Thermal Waters, an efficient agent in Metamorphism, 16. Metamorphism dependent on the chemical composition of the rock and the metamorphic agents, hence lithe- logical characters no criterion for determining geological age, 16. The constitu- ents of rocks pass from an unstable towards a more stable condition, 16; this passage a factor in the dissipation of energy, 16. Rocks are produced, grow old, and decay, but are not raised again, 17. Crystalline Structure no proof of great age or of great depth, 1 7. Long time not always allowed for the formation of fine-grained and fossiliferous rocks, 17. Contraction tends to maintain a uniform temperature in the Earth's interior, 17, 18. Relative Progression in geological time from abundant Acidic to abundant Basic Eruptives, 18. All Eruptives de- rived from the Earth's interior material which had never solidified, or which has since been reliquefied, 18. SORBY'S method of determining the origin of a rock misleading, 18. Association of Rocks is alone no proof of community of origin, 18, 19. Crystalline Schists naturally occur in a region of eruptive rocks, 19. Definition of Lamination, 19 ; this structure common in many eruptive rocks, 19. Joint Planes defined, 19; often mistaken in eruptive rocks for Bedding Planes, 19, 20. Cleavage defined, 20. Cleavage common both in Eruptive and Sedi- mentary Rocks, 20. Foliation defined, 20. Foliated Limestone mistaken for Mica Schist, 20. Foliation and Cleavage produced by the same cause at Squantum, Mass., 20, 21. Foliation common in altered eruptive rocks, 21 ; the planes being at right angles to the direction of pressure, 21. Schistose or Fissile Structure, 21. Fluidal Structure defined, 21. Schistose Structure often mistaken for Fluidal Structure, 21 ; the latter mistaken for Planes of Sedimentation, 21. Lines of chemical deposition taken for fluidal structure, 21. Arguments from analogy of doubtful value, 22 ; also from one region to another, 22. Evidence not sustain- ing the divisions of the Azoic System, 22, 23. Explanation of the structure of CONTENTS. vii districts of Crystalline Rocks, 22. Application of current views in American ecological Literature, 23. Association of Eruptive and Volcanic Rocks, 23. Origin of Crystalline Rocks, 23. Application of current views to Vesuvius in the time of STHABO, 24. Principles to bo employed in studying regions of Crystalline Rocks, 24. Materials of the earliest formed Lauds of eruptive origin, 24. Application of the term Eruptive or Volcanic in this work, 24. The younger Volcanic and the older Plutonic Rocks form a continuous series, 24. SECTION III. Tin: ORIGIN AND RELATIONS OF THE MINERAL CONSTITUENTS OF ROCKS . . . 25-30 The constituents of rocks fall into three classes, 25. Two divisions of the first rla-s, -~) ; action of the Magma on Minerals of the first division, 25. Inclusions in eruptive rocks, 25, 26. Action of Lava on Inclusions, 26. Microscopic charac- ters of Eruptive Rocks opposed to the theory of their derivation from Sediments, 20. Mineral products of the crystallization of a magma, 26. Mineral products of rock alteration, 2C. The chemical constitution of altered rocks not essentially changed, 26. Cause of rock alteration, 27. Alteration a character of the rock mass as a whole, 27. Altered eruptive rocks tend to simulate the features of sedimentary forms, 27. The general tendency of rock alteration, 27, 28. The concentration of ores in rocks, and veins attendant upon rock alteration, 28. Ores of mechanical and eruptive origin excepted, 28. Theory of ore deposits, 28. Mineralogy and Economic Geology chiefly sciences of abnormal minerals, 28. Unstable character of eruptive rocks, 28 ; their resemblance to chemical labora- tories, 29 ; passage from unstable towards more stable chemical combinations, 29. Induration not always an indication of exposure to heat, 29. The glassy state of rocks is nearest their primitive condition, 29. Designations employed for the three classes of rock-forming minerals, 29. Distinction of cases of envelopment from alteration products, 29, 30. Application of the principles of Thcrmo-optics, 30. The pyroguostic characters of a mineral have little or nothing to do with its condition before its formation, 30. The conditions under which minerals crystal- lize from a cooling magma are different from those under which vein and altera- tion minerals are formed, 30. SECTION IV. CHEMICAL ANALYSIS OF ROCKS 31,32 Chemical Analysis unable to determine the mineral constituents of rocks, 31, 32. While Chemical Composition remains nearly constant, great variation exists in the structure and mineral constituents, 31. What Chemical Analysis can do for the lithologist, 31. Relation of Chemical Analysis of normal rocks to rock species, 32. Analyses should be written in terms of the elements, instead of their compounds, 32. SECTION V. CLASSIFICATION BASED ON MINERAL COMPOSITION 33-45 Basis of the common classifications of rocks, 33 ; minerals used, and data re- quired, 33. THE FELDSPARS, 33-43. Their different modes of origin, 33. feldspar theory, 33,34; DELESSE'S views, 34 ; HKUMANN'S molecular viii CONTENTS. theory, 34. WALTERSHAUSEN'S theory, 34. Krablite a rock, and not a mineral, 34, 35. BUNSEN'S view of Baulite, 35. HUNT'S theory of the feldspars, 35. TSCHER- MAK'S theory, 35, 36 ; STRENG'S views, 36 ; PETERSEN'S objections to TSCHERMAK'S theory, 37. DANA'S method of accounting for variations in feldspars, 37. HUNT claims to have originated TSCHERMAK'S theory, 37. HUNT'S alteration of his direct quotation, 37. HUNT'S theory not original with him, and not the same as TSCHERMAK'S, 37. Writers who through misapprehension have acknowl- edged HUNT'S claims, 37, 38 ; SILLIMAN charges TSCIIERMAK with appropriation of HUNT'S views, 38 ; LEEDS recognizes the difference between the views of HUNT and TSCHERMAK, 38. The charges of appropriation made against TSCHERMAK false, 38. DESCLOIZEAUX on the optical properties of the feldspars, 38 ; FRIEDEL'S theory of their chemical constitution, 38 ; VOM RATU'S views, 38, 39. DESCLOIZEAUX'S discovery of microcline, 39. MALLARD and LEVY teach that it is the same as or- thoclase, 39. SCHUSTER'S observations on the optical properties of the feldspars, 39. Feldspars not suitable to found specific distinctions upon, 39. No means of positively determining the feldspar species in rocks, 40. DESCLOIZEAUX'S method of determining feldspars, 40; PUMPELLY'S modification of, 40, 41 ; PUJI- PELLY anticipated by LEVY, 41. The work of both independent, 41. HAWES on the distinction of feldspars, 41. BURICKY'S micro-chemical method, 41, 42. SZABO'S method, 42. GEO. H. EMERSON'S invention of a method of distinguishing minerals by means of crystals formed in blowpipe beads, 42 ; "amplified later by GUSTAV ROSE, \V. A. Ross, and H. C. SOKBY, 42. The specific gravity method for determination of the feldspar species, 42. Objections to the above methods, 42, 43. The twinning not constant in feldspars, 43. The chief value in lithology of the determination of the feldspars, 43. THE PYROXENE-AMPHIBOLE GROUPS, 44, 4:5. A variable series in them as in the feldspars, 44. Cleavage not a satisfac- tory basis for separating Diallage from Augite, 44. Augite found in Basic and Acid Rocks, and in the older and younger, 44. Alteration of Angite, 44. Sec- ondary origin of some Pyroxenes, 44. Relation of Hornblende and Augite, 44. The same hand specimen both a Diorite and Diabase, 44. The Mica Series, 45. Secondary origin of Chlorite and Epidote, 45. MINERALOGICAL NOMENCLATURE OF ROCKS. Rock Classification based on mineralogy alone, impracticable, 45. Rock Structure valueless for specific distinctions, 45. SECTION VI. NAMING ROCKS ACCORDING TO THE GEOLOGICAL AGE 45-47 Such nomenclature not natural, 45. No line can be drawn at the Tertiary Age, 46. Alteration under like conditions proportionate to age, 46. The petrogra- pher's duty, 46. The presence of Fluid Cavities in rocks, 46. VOGELSANG and JULIEN on Fluid Cavities, 46. Fluid Cavities sometimes original and sometimes secondary in rocks, 46. Occurrence in Tertiary Rocks, 46. The cause of the Crystalline Structure in the older rocks, 46, 47. The Granitic Structure, 47. SECTION VII. METHODS OF CLASSIFICATION 47-51 Classification the framework of any descriptive science, 47. The mineralogical method of studying rocks, 47. The natural method, 47. The relation of miner- als to rocks, 47, 48. Meaning of the Natural Classification, 48. Characterization CONTENTS. ix of the Mincnilogical Classifications of rocks, 48, 49. Compared with zoological methods, 49. Question of methods, 50. Earlier publication of these principles, 50. European classifications based largely ou altered rocks, 50. To express perfectly the Natural Classification of rocks requires perfect knowledge of them, 50. The classification here introduced empirical, 50, 51. Elasticity of the classi- fication, 51 ; its fundamental principles, 51. SECTION VIII. THE PRINCIPLES OF CLASSIFICATION 51, 52 SECTION IX. GENERAL CONCLUSIONS IN REGARD TO SYSTEMS OF LITHOLOGICAL CLASSIFICATION 53-59 Universal law of degradation of energy, 53. Natural classification conforms to it, 53. The demands of Petrography, 53. Expansion of materials in passing from the liquid to the solid state, 53. Pressure tends to render the Earth's interior solid, 53. Sinking of the Earth's crust, 53. The structure of the Earth indicated by petrographical and geological facts, 54. Crystalline rocks, 54. Systems of classification, 54, 55. Chemical analyses of rocks, 56. Alteration of rocks, 56. Divisions of minerals and rock fragments in rocks, 56. The order of arrange- ment of rocks, 57. Determination of a rock by means of its unaltered ground- mass, 57. Practical application of the principles of nomenclature and classifi- cation, 57. Specific and varietal names, 57. The use of the terms Melaphyr, Diabase, and Diorite, 57, 58. Sub-varietal names, 58. Trivial names, 58. Arrangement of the fragmental rocks, 58. Arrangement of rock names, 58, 59. Varietal and sub-varietal names not essential, 59. Use of a binomial and trinomial nomenclature, 59. CHAPTER II. THE SIDEROLITES AND PALLASITES. SECTION I. SlDEROLITE GO-G8 Definition of SIDEROLITE, 60. Shingle Springs, Eldorado Co., California, 60. Stanton, Virginia, 60, 61. Coahuila, Mexico, 61. Gibbs meteorite, Texas, 61. Butler, Missouri, 61. Toluca, Mexico, 61. General structure of meteoric sidero- lites, 61; constituents of, 61. Widmannstattian figures developed in, 62; also in Greenland iron, 62. Eeferences to illustrations of Widmannstiittian figures, 62. Further divisions of the Siderolites, 62 ; chemical analyses of, 62, 63 ; specific gravity of, 63 ; Iron in, 63 ; Nickel and Cobalt in, 63, 64 ; minor elements in, 64. Terrestrial Siderolites, 64, 65. Greenland iron, 65 ; its origin, 65. Doubtful me- teoric origin of many Siderolites, 65. Chemical analysis made sole test of mete- oric origin, 65, 66. Origin of masses of meteoric iron, 66 ; TSCIIERMAK'S views, 66 ; X CONTENTS. SORBY'S conclusions, GG, 07 ; objections to their theories, 07. The organic origin of meteoric iron and graphite, 07. MASKELYNE'S use of the term Siden/lite, G8. The terms Siderite aud Jlolosiderite, 08. SECTION II. PALLASITE 68-83 GUSTAV ROSE'S use of the term, 08. Definition of Pallasite, 08 ; arrangement of, G8. THE METEORIC PALLASITES, 69-75. Tucson, Arizona, 69. Hemalga, Peru, 69. Berdjansk, Russia, 69. Deesa, Chili, 70. Atacama, Bolivia, 70. Bitburg, Prussia, 70. Hommoney Creek, North Carolina, 71. Singhur, India, 71. For- syth, Missouri, 71. Anderson, Ohio, 71. Krasnojarsk, Siberia, 71, 72. Potosi, Bolivia, 72. Rittersgrun, Saxony, 72. Breitenbach, Bohemia, 73. Steinbach, Saxony, 73. Atacama, Chili, 73. Sierra de Chaco, Chili, 73. Newton Co., Arkan- sas, 74. Meyelloues, Bolivia, 74. Hainholz, Westphalia, 74. Lodrau, India, 74, 75. VARIETY. Cumberlandite, 75-83. Iron Mine Hill, Rhode Island, 75-79. State of the Iron of but little impor- tance lithologically, 76. Microscopic veins, 76. Hercynite (1), 77. Tracing altered conditions of Cumberlandite, 77-79 ; specific gravity of, 79 ; diminish- ing specific gravity with alteration, 80. First published description of Cumber- landite, 80. Study of other iron-bearing rocks, 80, 81. Tabcrg, Sweden, 81. General description of Pallasite, 81 ; of Cumberlandite, 81, 82. Chemical analyses of Pallasite, 82, 83. Chemical analysis alone suggests, but does not prove, the specific relations, 83. CHAPTER III. THE PERIDOTITES. SECTION I. INTRODUCTORY 84, 85 ROSEXBUSCH'S use of the term Peridotite, 84. How employed in this work, 84. Order of arrangement in the Peridotites, 84. The ueedlessness of subdivisions of Peridotite, 84 ; yet subdivided here in conformity to general usage, 85. Defini- tion of Dunite, 85. Proposal of the name Saxonite, 85. Definition of Lherzolite, 85. Proposal of the name Buclmfrite, 85. Definition of the terms Eulysite, Picrite, Serpentine, Porodite, and Tufa, 85. SECTION II. THE METEORIC PERIDOTITES 86, 106 VARIETY. Dunite, 80. Chassigny, France, 86; glass in, 86, 105. CONTENTS, xi VARIETY. Saxonite, SG-94. Iowa Co., Io\v;i, Sii-SS. Origin of the chomlritiu structure, 80, 87. Occurrence of a base in meteorites, 87. Dliurmsulii, India, 88. Kuyahinya, Hungary, 88-91 ; nrgank' remains in, s'.i. The constitution of meteorites such that they could not have existed in conditions suitable for life, 91. Choudritic structure, 91. ( Inadenfrei, Silesia, 91, 92. Gopalpar, India, 92; feldspar in it doubtful, 92. Bntsnra, India, 92, 93. Lance, France, 93. Touriuues-la-Grosse, Belgium, 93. Wacondo, Kansas, 93, 94. Goalpara, India, 94. VARIETY. Lherzolite, 94-101. Pultusk, Poland, 94, 95. New Concord, Ohio, 95, 96. Mocs, Transylvania, 96. Zsadany, Banat, 96, 97. Estherville, Iowa, 97-101. Iron globules in, 97, 98. 1'eckhainitc, 99, 101. MI:I;NII:K'S theory of the origin of the Estherville meteorite, 99, 100; objections thereto, 100. Variations in structure of this meteorite, 100, 101. VARIETY. Buchnerite, 101, 102. Tieschitz, Moravia, 101, 102. Peculiar character of its chondri, 101. Hungen, (Jenuany, 102. Grosuaja, Caucasus, 102. Alfianello, Italy, 102. MISCELLANEOUS, 103-105. Bavarian Meteorites : Mauerkirschen, Eichstadt, Schouenberg, and Krahcn- berg, 103. Caharras Co, North Carolina, 103, 104. Mezo-Madaras, Transyl- vania, 104-. Alessandria, Piedmont, 104. llenazzo, Italy, 104 ; special study should be made of this form, 104. Linn Co., Iowa, 104. Ausson, France, 104. Nanjemoy, Maryland, 104. Drake Creek, Tennessee, 104. L'Aigle, France, 105. "SVeston, Connecticut, 105. Chateau Henard, France, 105. Hessle, Sweden, 105. Nobleboro', Maine, 105. VARIETY. Tufa, 105, 106. Orviuio, Italy, 105, 106. Chantonnay, France, 106. SECTION III. THE METEORITES. THEIR ORIGIN AND CHARACTER 106-118 MASKELY.VE'S teachings, 106, 107. SORBY'S views, 107, 108. FORBES'S micro- scopic observations, 108. MEUNIER'S theory and FORBES" s criticism of it, 108, 109. '\'~-( HKKMAiv's idea of the tufaceous character of meteorites, and their eruptive origin, 109, 110. Objections to the preceding views, 110-112. The Chondritic Structure limited to a certain chemical and mineralogical type of meteorites, 110. Continuity of the Chondri and Matrix, 110, 111. Structure of meteorites rarely fragmented, 111, 112. Chondritic Structure produced by rapid crystallization, 111. Enclosures in meteorites, 111, 112. Meteorites derived from liquid, not solid material, 112, 113. The Sun, or some similar body, their most probable source, 112. Community of elements in the Sun and Meteorites, 112. Possi- bilities of Meteorites being thrown from the Sun, 113. Probable liquid condition of the Sun, 113. Meteoric constitution of some astronomical objects, 113. The theory that Meteorites are thrown from the Sun is old, 113, 114. Abundance of Metallic Meteorites in past times, I 1 1. Meteorites not thrown from the Moon, 111. and imt from the Earth in past times, 11 I. Need of further careful study xii CONTEXTS. of meteorites, 114, 115. Objections to SORBY'S view that minerals of unlike spe- cific gravity can intercrystallize, 115. Objections to HELMHOLTZ'H theory that the Earth is composed of meteoric fragments, 115, 116. Boulders in Northern Drift, fallen Meteorites, 110. Unscientific to suppose Meteorites have brought germs of life to the Earth, 116. Destruction of germs by the cold of space, 116. Meteorites not exposed to action of water and air, 116. Meteorites not vein for- mations, 117. Source of metals in veins, 117. Copper in Meteoric Rocks and Terrestrial Basic ones, 117. Metallic Iron in Terrestrial Basic Rocks, 117. Nickel, etc. in Meteoric and Terrestrial Masses, 118. SECTION IV. THE TERRESTRIAL PEUIDOTITES 118-162 VARIETY. Dunite, 118-125. Franklin, North Carolina, 118; structure indicates eruptive origin, 118. Webster, North Carolina, and alterations in, 119, 120. Tafjord, Norway, 120. Dun Mountain, New Zealand, 121. Sondmiire, Norway, 12L Eobcrgvik, Nor- way, 121. Bonhomme, France, 121,122. Karlstiitten, Austria, 122. Tron, Nor- way, 122. Heiersdorf, Saxony, 122. Ronda Mountains, Spain, 122, 123. Serrania de Ronda, Spain, 123. St. Paul's Rocks, their origin and alterations, 123-125. VARIETY. Saxonite, 125-128. Russdorf, Saxony, 125. Northern Norway, 125, 126. Thorsvig, Norway, 126. Birkedal, Norway, 126. Hovenden, Norway, 126. Rodfjeld, Norway, 126. Andestad See, Norway, 126, 127. Langenberg, Saxony, 127. Callenberg, Saxony, 127. The Ziegelei, Saxony, 127. Fatu Luka, Timor, 127. Eofna, Alps, 127, 128. VARIETY. Lherzolite, 128-147. Lake Lherz, France, 128, 129. Serram'a de Ronda, Spain, 129. Italy, 129. Ultenthal, Tyrol, 129. Colusa Co., California, 129-132; alteration structure in, taken for stratification, 130. Inyo Co., California, 132. Production of Magnetite during alteration, 132. Mohsdorf, Saxony, 132, 133. Rodhaug, Norway, 133. Baste, Harz, 133, 134. Christiania, Norway, 134. Gj0rud, Norway, 135. Presque Isle, Michigan. 136-138. Formation of dolomitic rocks, 137, 138. Eruptive origin of this Peridotite, 138. Ishpeming, Michigan, 139. Dolomitic rocks, 139. Transylvania, Austria, 139, 140. Fichtelgebirge, Bavaria, 140. Jaina River, San Domingo, 140. Starkenbach, France, 140. Todtmoos, Baden, 141. Plumas Co., California, 142. Levauto, Italy, 142. Euboca, 142. Philippine Islands, 143. Lizard District, Cornwall, 143. Troad, Asia Minor, 143-147. Dikes of Serpentine, 144. Diallage with Cleavage of Augite, 145. Schistose Rocks and their origin, 146, 147. VARIETY. Eulysite, 147-149. Tunaberg, Norway, 147. Kettilsfjall, Sweden, 147, 148. Varallo, Sesia Valley, 148. Lepce, Austria, 148. Fontanapass, Greece, 148. Mohsdorf, Saxony, 148. Gillsberg, Saxony, 148, 149. VARIETY. Ficrite, 149-152. Austria, 149. Steierdorf, Banat, 149, 150. Inchcolm Island, Scotland, 150. Herborn, Nassau, 150. Ellgoth, Austria, 150, 151. Anglesey, 151. Dillgend, Nassau, 151, 152. CONTENTS. xiii VARIETY, Serpentine, 1">:>~161. Fitztowu, Pennsylvania, 1">L'. Frankenstein, Sik-sia, 152. Leko, Norway, 152. \\ 'aldheim, Saxony, 153. Thessaly, 153. Santiago, San Domingo, 153, 154. La \Yga, Sun Domingo, 151. I'.rixlegg, Tyrol, 154. II Piano, Elba, 154, 155. Tasmania, 15."). Windisch-Matrey, Tyrol, 155. St. Sabine, France, 155, 156. River ( (isuin, Timor, 156. Riviere ties Plantes, Canada, 156. Melbourne, Canada, 156. Caliria. Spain, 150. High Bridge, New Jersey, 156, 157. Zoblitz, Sax- ony, l-">7, l.'is. Chip Flat, California, 158. Depot Hill, California, 158. Plumas Co., California, 158. Finland, 158. Klopfberg, Austria, 159. Nezeros, Thes- saly, 159. Fatn Temanu, Timor, 159. Westficld, Massachusetts, 159, 100. Formation of Talc, 159. Lynnfield, Massachusetts, 160. Hiver Joa, San Domingo, 160. Newport, Vermont, 161. Celinac, Austria, 161. Texas, Penn- sylvania, 161. Chester, Pennsylvania, 161. VARIETY. Porodite, 161, 162. Fatu Luka, Timor, 161, 162. Strand, Timor, 162. SECTION V. PERIDOTITE. ITS MACROSCOPIC CHARACTERS 162-165 Structure of the Meteoric Peridotites, 162. Structure of the Terrestrial Peridotites, 163-165; least altered forms, 163; alteration characters, 163. Ap- pearance of the Olivine Groundmass, 163. Alteration of the Pyroxene Minerals, 163, 164. Segregations in Serpentine, 164. Translucency of Serpentine, 164. " Slickensides " in Serpentine, 164. Products of extended alteration in Perido- tite, 164. Term Serpentine in Mineralogy, 164. Variability of Serpentine, 164; Schistose Structure in, 164. Production of Talc and Actinolite Schists, 164, 165 ; of Dolomitic Limestones, 165. Fragmentul states of Peridotite, 165. Origin of Ophicalcites and hrecciated Serpentines, 165. Introduction of the terms Merolite and Merolilic for pseudo-fragmental rocks, 165. SECTION VI. TERIDOTITK. ITS MICROSCOPIC CHARACTERS 165-175 General Microscopic Structure of the Meteoric Peridotites, 165-167. The Base of, 166. The Chondri of, 166. The Olivine of, 166. The Enstatite of, 166. The Iron and Pyrrhotite of, 166, 167. The Chromite and Picotite of, 166. The Manbhoom Saxonite, 167. Union of Diallage and Augite Cleavage in Dial- lage, 167. Lherzolite, 167. Minor minerals in Meteoric Peridotites, 107. Frag- mental Meteorites. 187. Microscopic characters of the Terrestrial Peridotites, 168-175; of Dunite, 168; alteration to Serpentine, 168. Transition in the varieties of Peridotite, 168. Characters of Enstatite, 168, 169 ; of Diallage, 169 ; of Augite, 169. Alteration of the Pyroxene Minerals, 109. Description of the alterations in the Peridotites as shown in the plates, 109-172. The ffozoim ques- tion, 172-174. Organic structure simulated in Felsites, 173. The supposed ''in, and other organisms, the more perfect, the more the rock is altered, 173. The inclination to unduly extend one's line of study, 17li, 171. Crucial test in disputed problems, 174. The KO-MHI in segregated or veinstone deposits, there- fore not of organic origin, 174. Microscopic charaet.-ra of Picrite, 174, 175. XIV CONTENTS. Obliteration of original characters in the process of the alteration of Peridotites, 175. Production of Schistose Structure in, 175. The supposed conversions of Schists into Serpentine, 175. Absence of the Mesh Structure and Chromito or Picotite in Serpentine due to alteration, 175. Formation of Serpentine Vein- stones, 175. Alteration minerals in Peridotite, 175. Ground covered by the text, 175. SECTION VII. ClIROMITE AND PlCOTITE. THEIR RELATIONS 170-186 FISCHER'S observations, 176. DATHE'S studies, 170. THOULET'S observations, 176. Translucency of Chromite first remarked in 1825, by C. H. PFAFP, 176. The writer's observations on some eighty specimens of Chromite, Picotite, and Ores of Iron, 177-180. Color and lustre of massive Chromite, 180. Hardness and streak of Chromite and Picotite, 180. Specific gravity of, 180. Coffee-broim color of, 180. Variability in color of, 180, 181. Observation of translucency, 181. Preparation of specimens, 181. Chemical relations of Chromite and Picotite, 181-183. Views of GENTH and RAMMELSBERG on, 183. Microscopic relations of, 183, 184. Conclusions regarding mineral species and their variability, 184, 185. A natural system in mineralogy, 185. Strange history of a Chromite Analysis, 185, 186. Errors in published lists of Analyses, 186. SECTION VIII. PERIDOTITE. ITS CHEMICAL CHARACTERS 18G-189 Designation of the varieties of Peridotite, 186. Specific gravity of, 186, 187. The Carbonaceous Meteorites, 186. As specific gravity decreases, the Iron dimin- ishes and Magnesia increases, 187. Microscopic characters of the Cold-Bokkeveld Meteorite, 186. Percentage' of silica in Pallasite, 187 ; of silica in Peridotite, 187, 188. Special case of the Cabarras Meteorite, 187. Percentages of alnminia, iron, lime, and magnesia in Peridotite, 188. The meteoric forms richest in Iron, 1 88. Alteration leads to decrease in the percentage of Iron, 188. Relation of Picrite to Basalt, 188. Minor elements in Peridotite, 188. Water proportioned to the amount of alteration, 188, 189. General chemical characters of Peridotite, 189. SECTION IX. PERIDOTITE. ITS ORIGIN 189-192 Eruptive occurrence of Peridotite in the Cornwall, Troad, and Lake Superior districts, 189. Relations of Schistose Rocks and Peridotes, 189, 190. Associa- tion of Eruptive and Schistose Rocks, 189. The Schists produced by alteration of Peridotite, 189, 190. Detritus of Eruptive Rocks, 190. Pcridotic Volcanoes, 190. Expected occurrence of Peridotites, 190 ; difficulty of the study of, 190. Production of Serpentine by alteration of Peridotite, 190. Migration of mineral matter, 190. Chemical precipitation of Serpentine from ocean waters, 190. Con- fusion between migrated serpentine material and that produced by alteration in situ, 190. Serpentine question allied to the phenomena of Eruptive Rocks and Veinstones, 190, 191. No proof that the Canadian Serpentines are stratified sedimentary deposits, 191. Believed inaccuracy of DR. HUNT'S writings, 191. CONTENTS. XV Production of Serpentine through alteration of other rocks than Peridotitc, 191. Literature of the Serpentine question, 191. Talcose Rocks derived from IVridotites, 191, 192. Steatite Hocks alteration forms of Gabbro and Diabase (Diorite), 192. Actinolite and other schists derived from Peridotite, 192. Am- jihilm h Schists, 192. Origin of Magnesian Limestoues, 192. Explanation of the alterations, 192. SECTION X. PERIDOTITE. ITS CLASSIFICATION 192-194 The use of Specific and Varietal Names, 192. Definition of Peridotite, 192. Basis of varietal distinctions, 193. Definition of the varieties, 193. Alteration varieties subordinate to the original niineralogical ones, 193. Probable varieties to be found by future study, 193. Most variety names not important, 193. Limburyite of ROSENBUSCH, 193. Terms applied to the fragmental forms of IVridutitc, 193, 194. Tabular Classification of Siderolite, Pullasito, and Perido- tite, 194. Essential terms in describing Peridotites, 194. CHAPTER IV. THE BASALTS. SECTION I. THE METEORIC BASALTS 195-200 VARIETY. Basalt, 195, 196. Stannern, Moravia, 195. Constantinople, Turkey, 195. Jonzac, France, 196. Petersburg, Tennessee, 19C. Frankfort, Alabama, 196. VARIETY. Gabbro, 196-205. Luotolaks, Finland, 196. Massing, Bavaria, 197. Juvenas, France, 197. Shcrgotty, India, 197, 198. Maskelynite, 198. Piiwlowka, Russia, 198. Lo Teillcnl, "France, 198. Bishopville, South Carolina, 199-201.. Chladnite, 199. Aqueo-igncous origin of Eruptives, 201. Mancgaum, India, 201, 202. Busti, India, 202. Shalka, India, 202. Ibbenbiihren, Westphalia, 202. Greenland, L'nj-205. Assuk, 203. Ovifak, 203, 204. Pfaff-Oberg, 204, 205. General Structure of the Meteoric Basalts, 205 ; not fragmeutal, 205. Nomenclature, 205. Future changes, 206. SECTION II. THK PSEUDO-METEORITES 20G-208 Wutcrvillc, Maine, 206, 207. Richland, South Carolina, 207. Igast, Russia, 207, 2Inf/>/ as that science which treats of the constitution and physical structure of rocks. It corresponds somewhat to the anatomy and histology of animals, including the study of morbid tissues. Science, 1883, i. 541. 1 2 THE STRUCTURE OF THE EARTH. Petrology treats of the origin, history, physical features, mode of occur rence, and relations of rock masses. Lithology is essentially an in-door or cabinet and laboratory science ; while petrology is exclusively a field study. The former needs for its pursuit hand specimens only; for the latter we must have the rocks in situ. Petrography I define as that branch of science which embraces both lithology and petrology. It includes everything that pertains to the origin, formation, occurrence, alteration, history, relations, structure, and classifica- tion of rocks as such. It is the essential union of field and laboratory study. So far as possible my work has been carried on according to petro- graphical rather than ordinary lithological methods, and with the belief that field evidence is stronger than any laboratory evidence can be in all matters relating to the origin of rocks. The facts developed by petrographical study seem to me to demand for their explanation a former liquid condition of this globe, and the admission that all rocks, not of organic origin, now forming a portion of the earth's crust, are the results either of that molten condition, or of the action of atmospheric and hydrous agencies upon the formerly liquid material. The belief in the former fluid condition is in accord with the demands of geology and the results of physical and astronomical research ; for it seems proper to hold, that, as is the present physical condition of the nebula?, stars, sun, planets, and satellites, so was, or is, or will be, this earth. Indeed the various phenomena with which we are concerned seem to be but the con- comitants and results of the passage of this earth from its active condition, as a hot fluid mass, towards a cold, inert, and passive state. Is it not our part to study matter in its present transitory stage, and from the facts thus gathered to reconstruct as far as possible its past history and infer its future course ? To me the beginnings, the various transitory stages, and signs of what the end will be, are apparent in the rocks ; and the effort of the classi- fication here employed is to give voice to these changes, or to the unstable- ness of the rock constituents, while the classifications of others appear in general to be based upon the assumed stability of the rock constituents, that is, they assume that as the rocks now are so they were, and always will be. I am unable to explain the facts obtained in the petrographical study of the rocks except on the supposition that the eruptive rocks of all kinds came from the interior part of the earth, and from below the sedimentary IS THE EARTH A SOLID BODY? 3 deposits ; moreover it would seern that they must come from a portion that has either never solidified, or which through some cause has been reliquefied. Here, then, it will be desirable that some examination should be made of the evidence derived from physical and mathematical laws on which is based the opinion held by many that the earth is solid. This evidence may be considered under two divisions. 1. That derived from the phenomena of precession and nutation, and of the tides. 2. That derived from the action of matter under the combined influence of heat and pressure. In the first case, the conclusions which have been reached have been obtained by assuming certain hypothetical globes with a certain definite structure, substituting for these the name earth, and then claiming that the conclusions applied to the actual earth instead of to the hypothetical globes, for which the name earth was used just as the algebraist uses x and y. Hop- kins assumed for his globes: 1, a homogeneous fluid mass enclosed in a homogeneous solid shell ; 2, a heterogeneous fluid mass enclosed in a hetero- geneous solid shell. The transition between the entire solidity of the shell and the perfect fluidity of the interior mass was assumed by him as being an abrupt one. He further assumed that the circulation would go on in the mass until it lost its perfect fluidity in every part at nearly the same moment.* Sir William Thomson, in the same way, drew his conclusions from globes assumed to have a thin shell, passing abruptly either into a homogeneous incompressible fluid, mobile like water; or into a heterogeneous viscid fluid interior.! Likewise Professor George H. Darwin has taken as the basis for his dis- cussions, if he is not misunderstood, homogeneous spheroids which are vis- cous and non-elastic, also those which are elastico-viscous, and those which are either elastic, plastic, or viscous.^ The view that the phenomena of precession and nutation prove the earth to be solid was opposed by Hennessy, Delaunay, || Newcomb and * Philos. Trans., 1839, pp. 381-423; 1840, pp. 193-208 ; 1842, pp. 43-55. t Trans. Koyal Soc. Edin.,1864, xxiii. 157-169; Plul. Mag .,1803 (4), xxv. 1-14,149-151; Phil. Trans., lM',3, ,,,,. 573-5S2; Trans. Geol. Soc. Glas., 1878, vj. 38-49; Nat. Phil., 1867, I. 670-727; Nature, 1S72, v. 223-2:24, 257-259. \ Phil. Tiaus., 1SSO, clxx. 1-35,447-593; 1882, elxxii. 187-230. Phil. Trans., 1851, pp. 495-517; Nature, 1871, iii. 420; 1872, v. 288, 289; Geol. Mag., 1871 (1), viii. 210-218. I! ((.!. Ma-, 1868 (1), v. 507-511. 4 THE STKUCTUREOF THE EAETH. others; and although strongly supported by Thomson for some fourteen years it was abandoned by him in 1876,* and is now generally given up. The view that the phenomena of the tides prove the earth to be solid is still sustained by Thomson and Darwin, but their conclusions only apply to the assumed globes and not to the earth itself. Their conclusions are also opposed by Hennessy, Fisher, Airy, and many others. The difficulty seems to be that it is beyond the power of any known transcendental mathematics to grasp the problem of the earth's structure, if its most probable condition be assumed. This condition may be described as being that of a globe having a density gradually increasing from the exterior inwards towards the centre, but with its materials heterogeneously arranged, and with the lighter crust gradually and irregularly passing into the heavier liquid beneath. If our attention be now turned to a consideration of the evidence derived from the behavior of matter under the combined action of heat and pressure, which behavior is said to prove that the interior of the earth is solid, the important questions are : 1. What are the materials forming the earth's mass ? 2. Do these expand or contract on passing from the liquid to the solid state ? In answer to the first question, it may be said that the results of petro- graphical study render it probable that the portion of the interior mass lying nearest the centre, and concerning which we have any data, is com- posed of iron,t either wither without nickel. As we recede from this portion we find pyrrhotite united with the nickel and iron. Then these minerals are further joined with olivine, or olivine and enstatite, in varying propor- tions, until a region is reached composed almost entirely of one or both of these silicates with or without diallage. From this we pass into the common basaltic rocks, then into the andesites, and so on outward into the trachytic, rhyolitic, and jaspilite forms. However true this order may have been for the liquid earth, it is certain that in the solid portions of the crust these materials are interlaced now with each other in every conceivable way, and that in the chemical and sedimentary deposits they have been intimately mingled. As to what may be the composition of the earth's mass nearer the centre, if there be anything there besides the iron and nickel, we have * Report Brit. Assoc. 1876, xlvi. (sect.) 1-12. f Whitney's Metallic Wealth of the United Slates, 1354, p. 434. Judd's Volcanoes, 1SS1, pp. 307-324. THEORIES OF THE EARTH'S SOLIDIFICATION. 5 no clew, unless it be that very possibly some of the rarer elements now found mixed with the iron may occur there. It was claimed by Sir William Thomson* that the earth must have solidified from the centre outward in accordance with the " thermo-dynamic law " of his brother Professor James Thomson, which may be stated in these words: All material* which contract on congelation Iiave their melting point rained b/j i; ivliile bodies which expand on freezing Jiavc their melting point lowered by Thomson, in common with nearly all physicists, held that the ex- pansion of water and that of bismuth on freezing, were exceptional cases ; but that contraction was the rule, and that pressure would therefore over- come the increment of heat as the centre was approached. The mistake made here was, that the cold solid was compared with the hot liquid ; the fact being overlooked that this law applies to the point of passage from the liquid to the solid, and not to the relative density of the two taken at tem- peratures differing hundreds and even thousands of degrees. Experiments t by Mallet, Centner, Millar, Whitley, Hannay, Anderson, Nies, Wiukelmann, and Wrightson show that in the case of steel, iron, tin, copper, zinc, bismuth, antimony, etc., compared, at a temperature just below the melting point, with the melted material at about its freezing point, the solid is the lighter ; but that these metals contract so on cooling that when cold all, except bismuth, are then heavier. It would seem that if solids and liquids are compared together at about the temperature of their con- gelation the solid is the lighter ; and that therefore the pressure at the earth's interior would cause these metals to remain liquid at a lower tem- perature than they would on the earth's surface. The same law holds good for slag, and seems to do so for lava ; in fact this is probably true of almost all rocks, although the evidence is far from being conclusive. Experiments J made by Hopkins, Bunsen, Mousson and others indicate that to change the fusion point a few degrees an enormous pressure is required, and that the law of Thomson is really capricious and variable, if always true. Hence, so far as our knowledge extends in regard to the * Traus. Geol. Soc. Glasgow, 1878, vi. 38-49. t Pn.c. Hoy. Soc., 1874, xxii. 3G6-3G8 ; 1875, xxiii. 209-234; Nature, 1874, x. 156, 157; 1S77, xr. 520, 530; xvi. 23, 21; 1878, xviii. 397, 398, 464; Proc. Roy. Soc. Edin., 1879, x. 359-362; Silz. Akad. Miincliuu, 1881, pp. 03-112; 1'liil. Mag., l^sl, (.")), xi. 295-299. } Report Brit. Assoc., 1S54, xxiv. (sect.) 57, 58; Ann. Pliysik Chcmic, 1850, Ixxxi. 502-567; 1S58, cv. 101-174; Everett's iVsduuuul's -\;it. Mill., 1872, pp: 312, 313; 1883, pp. 331, 332. 6 THE STRUCTUEE OF THE EARTH. action of matter under pressure and heat, there is fur more reason for believing the earth to be liquid than for taking the opposite view. From what has here been stated it would seem that there is no evidence drawn from mathematical and physical laws which obliges the petrographer and geologist to assume an interior structure for the earth different from that which the facts of geology and petrography would lead them to expect.* Starting, then, with the accepted belief that this earth was once an intensely hot gaseous body, it follows that if the heavier gases tend to lie nearer the centre than the lighter ones, the dissipation of heat could only take place through the slow conductivity of gases. In like man- ner, when the earth cooled down to a liquid mass convection would soon cease, if it ever existed, on account of the different densities of the earth's materials ; and here also the dissipation of heat would have to take place by the slow conduction of liquids. In the same way, in the solid portions of the earth the heat from the interior has to be conveyed outwards through broken, fissured, heterogeneous material. It would seem that all these conditions should be taken into account in all physical discussions of the age of the earth and sun ; but thus far all calculations seem to have been based upon the laws of the relation of gases and liquids of about the same density. There should further be considered the heat disengaged by the chemical unions necessary to form the present mineral combinations now existent on the earth. As the liquid earth cooled and its materials grew viscous, all interchange of materials would be retarded; and as the cooling continued, the lighter exterior liquid portion would form a hot crust, which would be lighter than the underlying liquid. On account of the viscous condition through which the earth's materials must pass before solidification, the crust would gradu- ally shade into the underlying liquid, and both would be nearly in the same condition with each other as to temperature. It is not probable that the crust would break xip and begin to sink, because, even if its surface grew cold, it would always have this hot solid base lighter than the underlying viscous liquid, which, owing to the increase of specific gravity as the in- terior is approached, would probably be more dense than any of the over- lying cold crust. Even if the crust should become heavier, break up, and begin to sink, this sinking would be very slow, on account of the viscosity * Whitney, Earthquakes, Volcanoes, and Mountain Buildiug, 1871, p. 74; Daua, Man. Gcb]., 18SO, p. 812. THE PltOHABLE CONDITION OF THE EARTH'S INTERIOR. 7 of the liquid, and its constantly increasing density ; while the heat imparted to the sinking material would tend to bring it to about the same specific gravity with the liquid portion as the sinking mass neared its melting point. But what is of still greater importance the sinking material would FOOII reach a liquid of different composition and greater density than the crust; and farther than this it could not sink. That sinking of the crust to the centre, which Sir William Thomson supposed would take place, could only do so in case the hot solid was heavier than the liquid interior, and that liquid homogeneous. But both these conditions appear opposed to what we know of the properties of matter and of the heterogeneous com- position of the earth. The structure of the earth that would naturally follow, from what has been above stated, would be a heterogeneous crust floating on a denser heterogeneous liquid, and one which the interior pressure tends to keep liquid at a lower temperature than on the surface, so far as it affects it at all. In an earth like this, owing to the gradual passage of the crust into the viscous liquid interior, no shrinking of the nucleus from the exterior could take place, but the earth would contract as a whole. A linear shortening of the crust would occur that would crush it together, and cause its depres- sion in some places and its elevation in others. The depression of any por- tion of the crust into the liquid interior would naturally cause an equivalent weight of the heavier liquid to rise, and perhaps overflow. This simple sinking of a portion of the crust on one side with its corresponding but less elevation on the other, with the attendant fissuring, would afford all the dynamic agencies needed to raise lavas to the tops of our highest mountains, and would account for the association of volcanoes with de- pressed basins, for fissure eruptions, etc.* The contraction could hardly be expected to be equal in every portion, while the depression of portions of the crust with the attendant outflows would cause an unequal thickness of the crust, with great irregularities in its base adjacent to the liquid in- terior. The outflows, themselves, would cause this crust to be tied through and through by the different eruptive materials. This great irregularity in thickness, which the earth's crust is supposed to present, .coupled with the viscosity of its interior portion next the crust, \\oald apparently prevent any direct or special connection between different * Whitney, Earthquakes, Volcanoes, and Mountain-Building, p. 90. 8 THE ORIGIN AND ALTERATION OF ROCKS. vents, even if they were near one another. The viscidity of the cooling liquid portion would, of itself, prevent any rapid flow of material from one point to another. But at the same time the liquidity of the interior mass would cause it to seek escape from pressure at any available opening, how- ever far that vent might be from the point of pressure. Yet the more viscous the material, the less applicable would be the ordinary law of the transmission of pressures by liquids. The part played by water in a volcanic eruption seems to consist mainly of its action on the lava during its passage upwards, instead of serving as the cause or primitm mobile of the eruption. It is difficult to see how lava in ascending to the earth's surface' could reach it without meeting water somewhere on its way. This. water with its attendant phenomena seems to be the accident, rather than the cause of the eruption. As stated before, a different view of the present structure of the earth's interior can be taken, which may not be inconsistent with the facts of petrography. This is that the interior, or at least the portion from which our eruptive rocks come, is solid, but in such a state that it can be readily reliquefied. This reliquefac- tion may be brought about either from increase or diminution of pressure, according as future experiments may show the relative densities of hot solid and liquid matter to be. The supposition that eruptive rocks come from these re-fused portions of the earth's originally solidified primitive material, would perhaps explain the origin of the minerals of the first or foreign class, to be spoken of later, which occur in these rocks. SECTION II. The Origin and Alteration of Rocks. THE theory of the origin of rocks generally taught in America is the following, with some more or less important modifications : The sedimentary (chemical and mechanical) rocks derived from the ruins of the "primeval crust" form all that portion of the earth's crust which is now known. By ordinary denudation these rocks would be removed from one point and depo- sited in another locality, the result being that the underlying sediments would be still more deeply buried in one place, and exhumed in another. The por- tions thus more deeply buried would be invaded by the earth's central heat, this giving rise to a more or less intense chemical action in them. The seat of this action is known as the " zone of aqueo-igneous fusion " (solution), and all sediments, if sufficiently deeply buried, come within this hypothetical Til KOI! IKS AT I'RKSKNT IX VOGUE. 9 /one. The different ])ortions of (lie sediments would be more or less affected ami metamorphosed, according to their chemical constitution, and their prox- imity to the hypothetical zone. If they came within the zone, their fusion or solution would give rise to lavas and volcanic eruptions. Some authors hold that every form of eruptive rock comes from sedimentary materials which have been thus acted upon; while others maintain that, although the true lavas and intrusive rocks may have been derived from non-sedimen- tary material, yet the sedimentary rocks take upon themselves forms undis- tingnishable from those of the volcanic rocks. Other modifications of this theory are delegating the source of the eruptive rocks to re-fused portions of the original solidified crust of the earth, which has been fused again on account of relief from pressure by denudation. This last view has been founded, so far as present evidence shows, on a misconception of the apparent general action of matter in passing from a liquid to a solid (not cold) state; therefore this should be abandoned, and fusion by increase of pressure either through the earth's contraction or by the deposition of sediments substi- tuted. Another theoretical view is simply a remodelling of the old Werne- rian hypothesis, and its application to the crystalline rocks. According to this view we are taught that all these rocks were deposited in pre-Cambrian time, and that all eruptive rocks have been derived from these chemical ones by aqueo-igneous solution or fusion. These crystalline rocks and their derived eruptive forms are then divided according to their lithological characters into distinct geological ages, and their age is said to be recogniz- able whether the rocks themselves be seen in their original form or in that of dikes and lava-llo\vs. If the above views are correct, we should expect to find in some form- ations rocks which had suffered every degree of alteration, the same rock passing from an unmetamorphosed condition into a highly metamorphosed or even eruptive one, with every gradation between. At certain points, when denudation has succeeded a former epoch of accumulation, the more or less deeply buried sediments would again appear upon the surface, showing greater or less evidence of the conditions to which they had been subjected. ly carefully selecting the localities to be studied, we naturally should ex- pect to find every degree of change in the rocks, and various transitions by direct passage from rocks unmistakably sedimentary into those that are truly eruptive, in their present position, from those rocks whose original iragmental structure is undoubted, to those that have been in a plastic, 2 10 THE ORIGIN AND ALTERATION OF EOCKS. semi-fluidal, or fluidal state. All these changes should exist in the same continuous mass of rock, and we ought to be able to trace the gradations from one place to another. That such passages have been observed, has been repeatedly claimed, but when the localities where these facts could be observed were sought for, they could not be found. The results of petrographical study seem to point to the following as the probable origin of rocks. If we start from a cooling liquid earth then all mechanically and chemically formed rocks have come from the liquid ma- terial originally. Furthermore, all the eruptive rocks appear to have come from below the sedimentary ones, and are only influenced by them in their composition, by the materials accidentally picked up during their passage through, or flow over the latter. In the case of volcanic rocks, we should expect to have associated with the lava, ashes, and in fact every kind of material projected from the crater, including debris and inud. All these would be naturally more or less intimately mixed together according as one was deposited on, or around the other, or as one in its flow picked up, sur- rounded, or overlaid another. This would associate all loose materials and rocks of any kind that existed in the locality prior to the lava flow ; while during that time and later the atmospheric agencies would tend to still more intimately mingle these diverse materials, and obliterate their differences. Wherever the lava was exposed to detntal action, there would be deposited about and around it detritus of the same material, mixed or not, as the case might be, with that from other rocks, especially if the eruption took place on or near the shore line. In the case of massive or fissure eruptions and dikes, we should expect but few or none of the common accompaniments of an ordinary explosive volcanic eruption, but all eruptive material would be subject to degradation, and would under proper conditions become associated with its own detritus and that formed from other rocks. All the associated detritus, if of one kind, would suffer the same alterations which non-frag- mental material of the same kind has to pass through. Under conditions otherwise identical, detrital material would doubtless be affected in a greater degree than the solid rock, owing to the former's greater perviousness to water. While in the unaltered condition we may be able to readily distin- guish the fragmentnl from the non-fragmental forms by the unaided eye, this is no longer possible when both have been subject to alteration. They then closely simulate one another, and the microscope used in connection with the field evidence offers the only means of distinguishing the fragmentul K\ \MIXATION OF CURRENT THEORIES. 11 from the non-fragnicntal form. When rooks of more than one kind are mixed in the detritus, the alteration and appearance of the sedimentary rock formed from this undergoes a corresponding modification. We should expect to find certain very intimate relations between all these various forms of associated rock, and it would be very difficult to dis- tinguish, in the older and more altered forms, between the material picked up during the flow, the ashes or debris, and the solid non-fragmental rock. The greater the amount of secondary alteration which these different rocks have sull'ered, the greater the difficulty of distinguishing between them. In no case, however, would the fragrnental pass into the non-fragmental form by insensible gradations or otherwise. It is true that they sometimes appear to do so, but that appearance is only superficial. In order then to decide between the different theories proposed for the origin of eruptive rocks, it is necessary to make some examination of the evidence offered in their support by petrographical study. For this pur- pose the most important question is, do sedimentary rocks take upon them- selves the characters of eruptive ones ? In the writer's studies he has found a certain resemblance between both classes of rocks when they are of similar composition. This is, however, only in the case of rocks greatly altered, and arises from secondary changes in each ; which result in the production of new mineral constituents, and in the obliteration of the original structure of both to a greater or less extent. Indeed, in some cases, this obliteration is total, the minerals and mineral characters in fact .ill the characters of the rocks thus changed being rendered unlike those which belonged to the original eruptive rock. These alterations are apparently more depend- ent upon the chemical composition of the rocks, and the conditions to which they have been subjected, than upon their having been in a fragmental or non-fragmental state. The result is, that the eruptive rock is degraded to the status of an altered sedimentary rock, not that the latter takes upon itself the characters of an eruptive one. Whether the two classes thus indicated can or cannot always be distinguished under the microscope in cases of extreme alteration, is a problem of the future, and perhaps the most difficult one with which the petrographer will be confronted. Undoubtedly, a careful study of the field relations of rocks would, in the majority of cases, suffice to settle the question of their origin. If sedimentary rocks should be found under peculiar and abnormal con- ditions, to present the characters regarded as typical of eruptive forms* Metamorpliism produced by the burning of Lignite Beds in Dakota and Montana Territories. By J. A. Allen. Proc. Bost. Soc. Nat. Hist., 1874, xvi. 240-262. 12 THE ORIGIN AND ALTERATION OF ROCKS. this would not be a basis for assuming that normally sedimentary rocks take these characters ; although this statement is one which is frequently made. Examinations have been repeatedly made by the writer for the purpose of ascertaining whether any rocks whose sedimentary origin was undoubted had acquired the microscopical characters of eruptive forms, but nothing of the kind has yet been discovered by him. In order to prove the passage of a sedimentary rock into an eruptive one, it is necessary to have on one side the undisputed fragmental form, and to trace it directly by continuous passage into the non-fragmental one. Not an inch of the parts lying between should be allowed to escape examination ; and it must be positively known that no line of junction exists, but that the two rocks form a continuous whole. In no case on record, however, does it appear that passages of the kind indicated, and which have been claimed as existing, have ever been subjected to so close an examination as is here demanded. Eruptive and sedimentary rocks at their line of junction usually mutually influence one another, often appearing very much alike, especially when they have been subjected to later alterations by which both have been affected. It is, then, to be expected that the observer who is not practically familiar with these occurrences will pass directly over the lines of junction, especially if he has been taught that direct passages of one rock into another may occur. His evidence is of that negative kind which, for various reasons, can usually be obtained with ease. The evidence that the two rocks do not pass into one another is of the positive kind, for the line of junction when once seen can be examined and re-examined at any time ; while hand speci- mens can frequently be procured which will show both kinds of rock and their junction in one fragment. We can then have positive field and laboratory (including microscopic) evidence that the two rocks are not the same but different ones. The writer has had frequent occasion to examine localities in which the direct passage of a fragmental rock into a non-fragmental one was said to occur, and in no case has he not been able to obtain positive evidence that such passage did not exist, when the conditions were such that a satisfactory examination could be made. When the evidence was lacking it was always owing to the junction being covered, or else shattered by jointing, frost, etc. Practically, when the existence of these junctions had been shown, the observers who had previously denied their existence have always said : "That is not a typical locality; we were not quite sure about that place, ORIGIN OF VOLCANIC ROCKS DISCUSSED. 13 but if you will go to such or such a locality, indicating some new one, you will find an undoubted passage of the sedimentary rock into eruptive Ibrms." \Vlicii this new locality is also examined and the statements are found to be erroneous, another one is mentioned, and so on; until one must demand hereafter of these observers that they shall select some locality on which they shall be willing to fully and finally stake their pet hypothesis, and abide- by the evidence. It has been claimed that the results of chemical analysis show that vol- canic rocks are derived from sedimentary ones. While it is true that the former have a composition chemically like some of the latter, this resem- blance is easily explained by the fact that a sedimentary rock ought to resemble chemically the massive rock from whose destruction it came. The chief difference between them would be that resulting from the change brought about by outside influences, the introduction of foreign material, etc. Hence the chemical resemblance between the two classes of rocks can naturally and readily be explained by the derivation of the sedimentary from the eruptive rocks ; .and there is no need to resort to the unnatural and hypothetical derivation of the volcanic from the sedimentary rocks. The former derivation is the one seen to take place every day, while the latter is unproved as yet, and those who hold it are apparently looking at the effect, and making it the cause. In other words, it seems to the writer that these observers have taken hold of the subject at the wrong end. In examining the products of volcanoes, certain minerals appear to be characteristic of them, which are of prior origin to the consolidation of the lava. These minerals show evidence that a hot magma has directly acted upon them, and every gradation can frequently be seen between the almost untouched mineral, and the nearly destroyed one. I regard these minerals, unless they were caught up by the lava during its passage from the earth's interior to its surface, as evidences that the material from which the lava was derived is no longer in its original con- dition, although this condition was not like that of any of our sedimentary rocks. Certain of these minerals are easily destroyed ; two at least, suffer- ing alteration readily on exposure, and it seems impossible that they could survive when the much less perishable materials of our sedimentary rocks have been entirely obliterated, if, as is supposed by many, they were ever there. These minerals are unlike, either in species, variety, or form, with possibly a few exceptions, any minerals occurring in sedimentary rocks as a 14 THE ORIGIN AND ALTERATION OF ROCKS. metamorphic product, i. e., not derived directly from the eruptive rocks. These minerals are characteristic not only of the modern lavas, but also of the most ancient eruptive rocks in which secondary alteration has not obliterated their characters ; not only in the modern basalt, but also in the ancient melaphyr; not only in the modern rhyolite, but also in the ancient felsite. These characters are not confined to any single locality or age, but are, so far as known, world wide, and go back to the earliest times in which such rocks occur.* We should then claim that the field evidence, as well as the microscopic, is opposed in toto to the prevailing theory that the eruptive rocks are derived from sedimentary ones. That theory demands immense duration of time, unstable continents, enormous forces, a solid earth that shall be more rigid than glass, and yet yield like a rubber ball to the slightest pressure of sedi- ments, lava flows, or glaciers. The theory in question demands the removal of immense masses from one place, and their deposition in another, the ele- vation of billions of tons in order to avoid the necessity of admitting the elevation of hundreds, for in order to have denudation that shall bring once deeply buried sediments to the surface, the entire mass must be lifted bodily above the surrounding region, or from the zone of aqueo-igneous fusion to the outer air. Which view requires the greatest force to elevate and depress such enormous bulks in a solid earth, or to raise our lavas from a liquid interior is plainly evident. This theory requires that volcanic action should be of modern birth Tertiary and that eruptive rocks of earlier date should have been produced by different forces a view now known to be false. To the theory that the crystalline rocks are chemical precipitates arranged in regular succession, there arises the serious objection that the oldest form the so-called Laurentian is cut by dikes of rocks which, according to that theory, could not have existed below them ; that is, they belong lithologically to the so-called Huronian and Norian systems. In contradistinction to the views here indicated, the writer's petrographical studies lead him to hold, with some others, that all volcanic or eruptive action arises from the original igneous state of the earth that it must have begun in the earliest ages of this globe. This action being a manifestation of a dying energy, must have been more active in the past than at present, although it may have been intermittent in character as all such forces seem to be. The products of this action have been the same from the earliest to * See also David Forbes. Nature, 1870, ii. 283-286 ; 1873, vii. 259-261. HOW AND \\1IKX ALTERATION TAKES PLACE. 15 the latest geological periods ; that is, a rhyolite, a trachyte, an andesite, or a basalt of the Azoic or Palaeozoic times, was the same when erupted as is the rhyolite, trachyte, andesite or basalt of the present day, or of the Ter- tiary age. The difference at present existing between these ancient and modern forms as the writer believes is due to the greater alteration which the former have suffered ; although possibly, a difference in the depth, or some peculiar condition prevailing at the time of the consolidation of the rock, may have had some influence in causing these differences. Under uniformly like conditions, alteration is proportional to the age, in rocks of the same constitution and structure ; but when rocks of like char- acter are subjected to the same agencies, for the same length of time, like results would be produced, let the age be what it will. The original crust and the eruptive rocks must, then, have furnished the material for all the other rocks, directly or indirectly, except such as was derived from water and the atmosphere. To trace these changes, and to follow the rocks in all their variations is the work of the petrographer. As did Cuvier with fossil l.oues, so may the lithologist reconstruct the original rock from the fossil fragments of it found in other rocks. The presence of fragments of one rock in another, however, is not to be taken as proof of difference of geological age between them, unless it can be proved that the inclosed rock is of sedi- mentary origin. A lava flow on a sea-shore would have its fragments in- cluded in any rock then forming, and this would hold true of all volcanic ejectments. A dike, also, passing through a rock forming on the shore, would have all materials broken from it inclosed in the rock then forming, but both would be of the same age geologically, although differing in order of time. In studying the alterations in rocks we ought not to confound the great molecular changes that go on through the rock mass as a whole, and those changes which are due to superficial weathering. The latter reproduce to some extent the characters of the former, but go to greater extremes, caus- ing in the end destruction and disintegration of the rock mass itself. The internal changes are apparently chemical or molecular changes in the whole rock mass, instead of simple pseudomorphic changes of single minerals. In no sense is metamorphisin to be looked upon as extended pseudomorphism ; for pseudomorphic forms are but an accident in the process of alteration, and they may or may not occur, according to the amount of that alteration. All the changes in rocks are to be explained by taking into consideration the 16 THE ORIGIN AND ALTERATION OF ROCKS. elements of the entire rock mass, and all elements brought into it by the percolating waters ; the chemical reactions taking place between any or .ill of these elements according to the special conditions, and not being confined to simple interchanges between the constituents of two minerals, as pseudo- morphs in mineral veins are usually explained. The failure to appreciate the above distinctions is believed to have led to the statement of much that is improbable in the works of many writers on pseudomorphic and metamor- phic changes in rocks. When we consider the petrographical structure of modern volcanic districts and the .alterations their rocks have undergone, we ought not to be surprised at the magnitude of the changes which we find to have taken place in rocks which have been subjected to similar conditions during countless ages. But these changes are metamorphic, and the rocks thus altered are metamorphic rocks. Metamorphism, however, does not appear to be lim- ited to rocks of one kind, but affects all classes. The amount of metamor- phism any rock undergoes under the same conditions seems to be inversely proportional to the amount of contained silica ; and this change apparently began as soon as any of the earth's solid material was exposed to the com- bined action of air and water, and has continued up to the present day. Volcanic or eruptive action, including a subsequent prolonged exposure to hot water, accompanying the dying eruptive force, appears to have been an efficient agent in metamorphism. According to the above view, the metamorphic rocks produced would be dependent upon their chemical composition and the agency by which the changes were effected, but would not be at all dependent upon the geolog- ical age. Hence lithological characters would be valueless as a criterion for determining the age of such rocks. The writer finds that the constituents of the eruptive rocks and their derivatives pass in their alteration from the unstable towards more stable compounds in the conditions to which they are subjected, that is, they pass into forms that never can in the ordinary course of nature return to their original condition. In this there exists a potent factor for the dissipa- tion of energy. The potential energy of the original chemical combination is in a greater or less degree lost, and cannot be restored except by some foreign power, or, in other words, the original structure and composition cannot be normally regained. The advocates of the sedimentary origin of igneous rocks, however, require the restoration of that lost energy, and TIIKORIES OF ALTERATION DISCUSSED. 17 advocate a sort of perpetual motion. According to them these rocks are born, grow old, and die, and their remains are raised again and again, that the process may be repeated. The writer accepts the birth, old age, decay, and death ; but he doubts the resurrection and believes that such views are opposed to physical laws. A crvstalline structure is indigenous in any eruptive rock, if it remains in a condition that allows it to slowly crystallize; and this structure is not therefore any proof of great age in a rock, or a sign that it was formed at great depth.* From the above it would follow that such rocks as the felsites cannot be taken as characteristic of certain ages (Arvonian or Huronian) ; but if as the writer, with others, holds they are old rhyolites, they have been formed in all ages. Again, while they may have been deeply covered with detrital beds, there is no necessity for such a burial, or any proof that they were once thus covered, any more ' than there is that the modern rhyolites have been. Also, the claim for long times for the formation of rocks which are fine- grained and fossiliferous cannot always be allowed ; as for instance, the Florissant shales,t or a large deposit of fine, dust-like powder, observed in the vicinity of the Black Hills by my colleague, Mr. Samuel Garman. This powder is made up of minute fragments of volcanic glass, forming a bed several feet in thickness. If it had not been for the revelations of the microscope, would not some geologist be computing the number of thou- sands of years it would take to form these deposits " as Nile mud," when perhaps, a few weeks or even days were sufficient for this purpose. If the deposits in question had been subjected to sufficient alteration to obliterate the original texture, who would have been able to prove the falsity of the theory of a slow deposition of the material as an ordinary sediment? Another illustration is afforded by the Lake Superior sandstone, which shows that extreme care is required to ascertain the conditions under which any deposit formed, before the length of time required for its formation shall be estimated, t To the objections offered to lavas being the same from all time, on account of the difficulty of believing that the same portions of the earth's * Bull. Mus. Comp. Zool., 1880, vii. 111. f Bull. U. S. Geol. Survey, 1881, vi. 286, 287. J Bull. Mus. Comp. Zool., 1880, vii. 177, 118. 3 18 THE ORIGIN AND ALTERATION OF ROCKS. interior have been liquid since the Azoic time, it may be replied that if contraction suffices to keep up the heat of the sun to an approximate uniformity, so too the contraction of the earth would tend to maintain a uniform temperature in the earth's interior ; a point that it is necessary to consider in all discussions relating to the earth's age. It may again be suggested that, while basic rocks of the same character as those seen to- day were erupted in the early ages of the earth, yet there has been on the whole a progression from the acidic to the basic, in relative abundance, from earlier to later times. Furthermore, owing to the irregularity in thickness with which the earth's crust has apparently solidified, great diversities would be expected to exist in that part immediately below the crust in different portions of the earth.* Whether volcanic and all other eruptive rocks came from material that has never cooled to a solid state since the earth began to solidify, or whether they are derived from a portion that solidified, but has since been reliquefied, is a problem for the future, the solution of which hinges on the origin of the partially destroyed materials in the rocks themselves, were they caught up on the passage of the lava to the earth's surface, or are they the remains of a prior crystallization ? If we turn to Sorby's method for determining the origin of rocks by the inclusions in the contained minerals, we find that it may possibly answer in recent, surface-formed rocks; but that in the old and altered forms it seems to carry us astray, and serves but to retard the advance of our knowl- edge of rock formation. This is especially the case if the secondary min- erals, like quartz, have been formed later in the rock in question by the action of hot waters. Conclusions regarding the origin of a secondary or foreign mineral included in a rock ought not to be transferred to the rock itself, as those who use Sorby's method are in a habit of doing. The somewhat common argument that a rock associated with crystalline schists must have the same origin as the schists, would make a dike in slate of the same origin as the slate. Association of rocks proves nothing, for in volcanic districts, in limited areas even, rocks of every character can be found together. Should we then hold that because some were sedimentary, all the others were so ? Or, again, should we claim that because some were eruptive, all the rest were eruptive ? No ! we ought to prove the origin of each rock, and in every locality in which it occurs, so far as possible, and when evidence is wanting leave the question as undetermined. * Whitney's Volcanoes, Earthquakes, aud Mountain Building, pp. 69-107. IMIKIMTIONS OF TERMS USED. 19 A region in which eruptive rocks abound is a region in which crystal- line schists would naturally he expected to occur; for here the conditions of mi'tamorphism are best developed, conditions that affect and metamor- phose all the associated rocks, both eruptive and sedimentary, according to their composition and physical structure. Eruptive rocks, whether in dikes or lava Hows, ashes or detritus of any kind, frequently possess the charac- ters of crystalline schists; must they therefore be regarded as being of sedimentary origin ? The writer has seen dikes of crystalline schists cut- ting directly across schistose conglomerates and other sedimentary rocks. AY;is he to conclude that these dikes of schist were sedimentary, and had been intruded in the form of schists; or rather that they were of eruptive origin, the original rock having been later metamorphosed into a schis- toIM KNTAKY A( IKXCI KS DISCUSSED. 23 geologist be placed upon this old volcanic ground worn down to its roots, its locks altered or metamorphosed, its remnants of mingled lava flows, eject- amenta, and marine deposits, and let him be asked to give its history. If he Avere educated in the prevailing views current in American geological liter- ature, it is probable that he would declare that this was an old chemical or sedimentary deposit, which had been buried thousands on thousands of fort deep under other sedimentary deposits, and in which, owing to the inclosed moisture and the rise of the internal heat, an aqueo-igneous solu- tion had set in, rendering the formation plastic. He would also say, that owing to the generated gases and pressure, the lower portions of the deposit had been forced into the upper ones, and every gradation had been produced between the normal sedimentary rock .and eruptive forms, which pass by insensible gradations into each other. How easy and simple would this explanation be! nothing could be shown which the authors of such theories could not explain. But how false in onr supposed case such an explanation would be. If we add to onr supposed volcanoes massive eruptions, with or without fragmental ejections (explosive action), shall we not have the same petrographical features that now exist in regions of the older crystalline rocks ? and is the explanation generally adopted for them any more accurate ? The intermingling of eruptive and detrital deposits here supposed is described in almost every work on volcanic action, and it has been clearly shown, in many of these districts of older crystalline rocks, that the series of events here indicated has been very common. That sedimentation has done its part the writer believes, and he has not the slightest wish to belittle its importance; but that it has done everything he does not believe. Whether any of the first-cooled masses may ever be found, is a problem for the future ; but that we have to do with material that was fluid before sedimentation began, we consider is clearly established. To volcanic phenomena, whether explosive or massive, and to the as- sociated water action, appear to be due the phenomena of crystalline rocks, which occur in any and every age from the earliest times to the present. Especial stress has here been placed upon the characters and phenomena of eruptive rocks, in hopes of bringing about a state of geology in which the opposing eruptive and sedimentary agencies shall both have their proper share, which at present they do not have, on account of the extreme to which the advocates of sedimentation have now carried their views. 24 THE OEIGIN AND ALTERATION OF ROCKS. The views of sedimentation have been pushed so far that one wonders if Strabo, after he had described the volcanic characters of Vesuvius, was not told by his cotemporaries that it was all a mistake that the peculiar char- acter of the rocks was owing to chemical deposition or to mechanical sedi- ments ; that all showed the slow accumulations of millions of years on a slowly subsiding sea-floor ; that the whole had been buried many miles under the accumulating sediments, rendered plastic, causing dikes to be formed ; that all the different rocks passed by insensible gradations into one another, etc. ; and that, finally, the whole mountain was carved out by the slow process., of the removal of the sediments, and was imdoubtedly, owing to the crys- talline character of its rocks, one of the earliest formations of the globe. In working in regions of crystalline rocks, the principles should be used that one would employ in studying districts in which modern volcanic action has existed, as about Naples, Mount Etna, Iceland, western North and South America, and Japan. If this is done, and the older districts are examined by the aid of the light given by the modern eruptive formations, the writer believes that the pres- ent obscurity enveloping the former would be cleared away. The greatest difficulties in the study of such regions seem to have been in the theoretical views of the observers themselves. The question regarding such rocks should be, what are the facts, and not what are the theories. It seems to the writer clear that the earlier formations of which we have any record in the earth's crust were not derived from the waste of earlier lands, but rather that they are for the most part eruptive, if not portions of the first formed crust ; and that the fragmental portions were eruptive ashes, or were derived from the waste of eruptive material.* The burden of proof rests upon the advocate of ancient destroyed conti- nents, to show that the materials which he supposes came from such lands could not have been derived from the eruptive action of that early day. The term eruptive, or volcanic, has been applied in this paper to all rocks coming from beneath the surface, showing signs that they have been in a fluid condition, whether ancient or modern, for nature has not, to my belief, drawn any line in her rocks between the younger volcanic and the older plutonic forms, but all form a continuous and harmonious whole. * Gcikie, Text Book of Geology, pp. 12, 13. THE MI NEK A I. CONSTITUENTS OF ROCKS. 25 SECTION III. The Origin ami ]!< hit inns of the Mineral Constituents of Rocks. TAKING the consolidation of any rock as the initial point, particularly those of an eruptive nature, the constituents fall into one of three classes: I. Those of prior origin ; II. Those formed at that time ; III. Those of later origin.* The minerals of the first class naturally fall into two divisions, in the eruptive rocks. 1. Those that are characteristic of the rock species. 2. Those that are accidental, being probably caught up in the passage upward or during the outflow. Similar divisions are found to a greater or less extent in the sedimentary rocks, according as they were derived from one or more rocks, and also according to the preponderance of different rock fragments and minerals in them. The minerals, and fragments of minerals and rocks, occurring in rock masses that belong to the first-class, have an important be ( aring upon the questions of the origin and relations of rocks so much so that more atten- tion will be given to them in the future than has been the case in the past. These are in a great measure characteristic of the rock species, and should have a very great weight in the nomenclature of sedimentary rocks ; for one of the most important questions regarding these is, what was the original material from which they were derived? In the volcanic rocks these minerals are distinguished generally by the effect that the magma has produced upon them the blackening, breaking, tearing, and dissolving action which is so conspicuous in the case of olivine and hornblende; while in quartz it is shown in the fractures, the rounding of the grains, and the interpenetration of the magma. Frequently these foreign materials, especially quartz, have radiating rings of the groundmass surrounding them, these rings being largely composed of crystals standing perpendicular to the surface of the inclosed piece. In all rocks of an eruptive nature, the fragments are apparently either inclusions caught in the passage upward, or during the surface flow of the lava, or else derived from the remeltiug of the more crystalline portions of these or other rocks at the time of, or prior to the eruption ; especially when the eruption A. Michel Levy, Bull. Soo. fieol. France, 1874 (3), iii. 199-230; Ann. Mines, 1875 (7), viii. 341- 340; \Vadsworth, Bull. Mu.,. ('.m,p. Zoul., 1S79, v. 277, 278. 26 THE MINERAL CONSTITUENTS OF ROCKS. took place in an old vent, from which the plug of lava and ashes must be removed before the outflow could occur. The action of lavas upon these foreign inclusions seems to be that of a corrosive dissolving hot magma or solution, which penetrates and gnaws its way into the included fragments. Two cLisses of foreign materials seem to be characteristic of most of the eruptive rock species simple minerals, and rock fragments. The latter are either the same as the inclosing rock or else they are the same as some rock known to have reached the earth's surface earlier in order of time. These mineral inclusions characterize the same rock type" from the earliest times to the present, when- and where-ever they may occur. All this indicates some deep seated universal cause beyond the influence of sedimentary rocks. These characteristic minerals, too, are not such as occur in sedimentary rocks ; while no such admixture of material exists in the eruptive forms as would naturally be expected to occur if they were .formed from sediments. Then too, the minerals and fragments of the more difficultly altered sedi- mentary rocks ought to have remained side by side with these easily alter- able foreign minerals in eruptive rocks, if the latter rocks are the re-fused portions of the former. The microscopic characters of the eruptive rocks are to my mind utterly opposed to any theory that they come from sedi- ments, or anything else than the original liquid material of the earth. The second class of rock constituents naturally occupies the most promi- nent place in recent volcanic rocks, and a more subordinate one in the older eruptive and sedimentary ones. In eruptive rocks, the indigenous materials are the products of the magma when unacted upon by extraneous agencies. It is doubtful if any minerals come under this head direct primary pro- ducts of crystallization of the magma except anhydrous silicates and oxides, a few phosphates, sulphides, and native elements, the other minerals in the rocks belonging to the other two classes. The third class becomes very prominent in the older and altered rocks, and includes the hydrous and some anhydrous oxides and silicates, carbon- ates, and most sulphides. These forms are the products both of alteration taking place in the rock mass and of material brought into the rock from extraneous sources. In one case the chemical constitution of the rock remains essentially unim- paired, while in the" other that constitution is changed to a greater or less degree. The causes of these alterations in ancient and modern volcanic THEIR ORIGIN' AND RELATIONS. 27 rocks is but imperfectly known, but the changes probably take place under the influence of percolating waters. That these changes are slow in many cases is rendered prohaMo by the fact, that when rocks have been exposed to rapid alterations by hot and mineral waters, the result is a general de- struction of the rock mass, a disintegration of it as a whole, and not such changes as are seen in rock masses in general. It is probable that both cold and thermal waters have contributed to the change, as the latter are abun- dant in volcanic regions at the present, and we have the right to infer that they were so in past time at the localities in which, ancient igneous activity was manifested. These alterations are considered to be molecular, or belonging to the rock mass as a whole, although some portions and some minerals are altered more rapidly than others. The general tendency of rock alteration seems to be the breaking up of the original constituents, and the formation of quartz and other minerals, that give to the rock characters closely simulating those of sedimentary rocks. The sediments also undergo the same changes, and in extreme cases produce crystalline schists and gneisses. The changes in them are appar- ently brought about by the same agencies as the changes in eruptive rocks, and thermal waters may have been an important factor in producing crys- talline structure in the former. In the various alterations of the rocks of every kind the new mineral structures come apparently from the segregation of mineral matter, either from the rock or adjacent sources, in some place suitable for its deposition. The place may be some fissure or cavity, or it may be in the solid rock mass itself, by the removal of one or more chemical constituents from the immediate point of action, and the substitution of others. So far as the rock mass goes when no foreign material is carried into it, these changes may be defined as the migration or aggregation of the chemical elements, produced by their tendency to seek such unions as shall expose them under their present con- ditions to less disturbing elements than their former relations did a ten- dency to pass from an unstable towards a more stable condition. The final result of these changes is, usually, to produce clays, ochres, quartz, and car- bonates ; the latter of which while not stable in position, are apt to be so iu composition ; e. //., calcite, while readily soluble and removed, generally reappears as calcite the position unstable, the union stable. The general principle of change is the same, whether the mineral matter be reprecipitated 28 THE MINERAL CONSTITUENTS OF BOCKS. in the rock mass itself, or is carried out and deposited in any contiguous cavity or fissure, or borne away to be deposited from thermal or mineral springs, or from bog, river, lake, or ocean waters. The efforts to explain the changes in rocks and in their mineral con- stituents by theories of pseudomorphism have generally failed, because the changes have been attributed to the single minerals, and not to the rock mass as a whole. The concentration of ores in rocks, and the formation of mineral veins seem to be brought about by the same process as the more common altera- tion of the rock mass, or the storing up of the material in minute fissures in the rock.* The only difference is that the kind of material and its amount, owing to the size of the receptacle and the extent of the action, is such as to make it commercially valuable. In this statement there would be excepted all ores that can be proved, as some iron ores have been, to be of eruptive origin, as well as all mechanical deposits. In this connection it may be explicitly stated, the writer holds the view that the elements of most of the ores were disseminated through the original and eruptive rocks, and that when these rocks became exposed to the action of meteoric agencies, these scattered materials were collected and deposited in the veins and segregations in which they are now formed.! So far as now known, the only ore of eruptive origin, in masses sufficient for exploitation, is that of iron, which is so only in part of its occurrences. If this view is cor- rect, it would follow that our veins and most of our ore deposits are superfi- cial phenomena J of the earth, and that mineralogy and economic geology as ordinarily studied relate chiefly to the secondary products of mineral matter; or, they are the sciences of abnormal minerals. The above described alterations in rocks and minerals, and the localiza- tion of mineral deposits, with the consequent essential original unity of ancient and modern rocks, naturally follow from the general law of the passage from the unstable towards a more stable condition. This results from the fact that the original materials of the earth, whether forming the original crust, or appearing on the surface as eruptive rocks, are in a higher state of energy than is adaptable to the surface conditions of this globe. They are unstable both in temperature and in the majority of chemical combinations formed on solidification, and heat is lost with a resulting * Bull. Mus. Comp. Zool., 18SO, vii. 123-130; Proe. Bost. Soc. Nat. Hist., 18SO, xxi. 01-103. f Eng. Min. Jour., New York, 1884, xxvii. 361, 365. J Whitney, Aurif. Gravels, pp. 350-301. THEIE CLASSIFICATION. 29 dissipation of energy ; while the chemical elements or the molecular combi- nations tend to seek new unions better adapted to the present circumstances of the rocks. These changes progress, going on from one form to another. It is not uncommon to find that as steps in the progress, the original miner- als and glass are altered to other more or less well defined minerals, having sometimes perfect crystalline form; while these in their turn yield to the act- ing forces, and new mineral combinations are entered into, and so on down- ward in the course of the alteration. It may be said that an eruptive rock, when it has passed from the interior to the exterior of the earth, becomes a chemical laboratory, in which solutions, reactions, and precipitations are continually carried on experiment after experiment, change after change, succeed one another, according to the materials, reagents, and conditions. But they always progress in one direction ; the combination last formed is ;il\v;iys more stable in the then conditions than the preceding combinations were ; with any change of condition there would of course come change in relative stability. The induration or hardening of rocks would thus oftentimes be no index of exposure to heat, for if the mineral formed or infiltrated into the rock mass is one which stands high on the scale of hardness, e. g. quartz, then induration follows as a matter of course. From the principle of passage or unstableness it follows that the glassy state is nearest the primitive condition, and is to be looked upon as the starting point of the indigenous and secondary minerals in rocks; hence it should come first in our study and be traced in its process of crystallization and alteration. The three classes of products above discussed will be mentioned hereafter as products of the first, second, and third class, or as, 1st, foreign ; 2d, indi- genous; and 3d, alteration or secondary products. The two first classes have been collectively and singly called by the writer original in contradistinction to the secondary products. Cases of envelopment occur in minerals of the second class frequently, but they can be distinguished as easily under the microscope, in rocks not too far altered, from the foreign or secondary minerals, as a coarse conglom- erate can be distinguished from a granite by the naked eye, or as a piece of wood joined to another by a mortise and tenon can be distinguished from the natural growth of a limb. The various changes that rocks undergo in their alterations are determined 30 THE MINERAL CONSTITUENTS OF ROCKS. under the microscope, the same as changes are determined in objects in botany, zoology, and astronomy. It is not necessary that one should see an acorn grow to an oak, an apple-seed grow to an apple-tree, a lamb to a sheep, a nebula to a star, before he can reason upon the growth of plants, animals, and stars.* It is sufficient to be able to study these in various stages of their growth, in order to make out their history to examine numerous specimens that exhibit all the various phases of existence, to make out the general life histor}' of the individual. So in lithology the history of the rocks and minerals can be made out as distinctly and certainly as the life history of the individuals in the other subjects before mentioned. In applying the principles of thermo-optics to the mineral constituents of rocks, in order to determine at what temperature the rock was formed, it should be remembered that it is only the minerals of the first class to which they apply. These alone must have been subjected to the heat of the liquid magma and present permanent marks of that action. Of course, nothing can be asserted concerning the temperature to which a liquid has been exposed, from either the thermo-optical or pyrognostic characters of the resulting minerals arising from its cooling under various conditions;! in other words, the characters of a mineral after it is formed have little or nothing to do with what it was before it was formed, except so far as the relation may have been shown to exist, by experiment and by observation of the same conditions. Investigations upon the thermo-optical properties of minerals belonging to the first class would probably lead to interesting results, if care were taken to select such as are typical of the lava. It should also be kept in mind that the conditions under which minerals are formed from the crystallization of a cooling magma are different from those under which minerals are formed in veins, fissures, and cavities, or by alteration of the rock mass ; and that minerals truly of the second or indige- nous class occupy a very subordinate position in our mineral cabinets. * Peirce, Ideality in the Physical Sciences, 18S1, p. 69. f As well predicate what was the temperature of the water glass and hydrochloric acid, from the amount of beat it takes to fuse the chalcedonic silica which they form under suitable conditions, as to attempt to prove the heat of a liquid magma from the fusion point of some mineral crystallizing out of its cooling solution. The temperature at which a mineral fuses and the temperature at which it formed have no connection with one another, except in the case of crystallization from dry fusion ; if they do, how hot corals must be ! VALUE 01'' CHEMICAL ANALYSIS IN L1THOLOGY. 31 SECTION IV. Chemical Analysis of Hocks. AT the present time the most that chemical analysis seems to be able to do for the lithologist is to give the composition of the rock as a whole. The many attempts that have been made to determine the mineralogical composition of rocks by unaided chemical analysis appear to have been in almost every case a failure. This is natural, for this method alone is unable to take into account the three different classes of minerals in rocks, and in its statements has to proceed as if all the minerals were the pro- ducts of free crystallization in the rock. But while the chemical composi- tion remains about the same, every gradation in structure and mineral composition is known to exist, from a pure glass to mixed glass and crystals, to a purely crystalline rock, and to one in which all the mineral constituents are secondary or alteration products. Since the chemical composition of all these forms is essentially the same, the results of any calculation of the percentage and kind of minerals inclosed, would be nearly the same ; but how different from the reality are the results of the calculation, except when the rock is composed of crystals of the second class alone. Even here the correctness of the result would be a matter of doubt. Chemical analyses of rocks, showing their ultimate constitution, if made from specimens carefully selected and studied in the field, and further studied microscopically, would aid greatly in lithological research. Typical unaltered specimens are needed to establish rock species ; and for such work the average specimens of collectors are too much affected by surface altera- tion, or weathering, to be used. But a large proportion of rock analyses appear to have been made from such unsuitable specimens, of whose struc- ture, mineral composition, and field relations we know nothing, or next to nothing; this, too, when the chief value of such analyses is to enable us not only to institute comparisons between the chemical composition of the rock analy/ed and that of other rocks, but also between that composition and its origin, structure, mineral composition, and physical relations. Chemical analyses could be made of great service in lithology by taking a graded series of rocks, beginning with the unaltered form, and passing gradually into the extremely altered form, comparing step by step the chem- ical composition with the changes in structure and mineral composition. 32 CHEMICAL ANALYSIS OF EOCKS. There is a vast amount of unconscious humbug in the constant attempts to use chemical analyses for a purpose foreign to their nature ; that is, to determine, as before mentioned, the mineral composition by mathematical calculations founded on rock analyses. All these efforts appear to be based on an entire misconception of the nature of rocks. Nothing better illus- trates the inutility of this method alone for the purpose of determining the mineral composition, than a comparison of the speculations of chemists regarding the minerals composing the stony meteorites and the actuality as obtained by microscopic examination. The writer holds, as the result of his studies, that the chemical analysis of a normal rock corresponds with its species that is, certain percentages of the more prominent elements can be laid down, beyond the extremes of which normal rocks belonging to that species will rarely if ever go, and within which normal rocks of other species will rarely if ever come. This, of course, applies especially to the eruptive rocks, for in the case of the sedimentary ones, every degree of composition is to be expected according to the sources from which the materials composing them were derived, and the amount of sorting, chemical replacement, etc., they have undergone. The more highly altered or weathered eruptive rocks, especially if chemical constituents have been removed, and either replaced or not by others, would not be normal forms. If the analyses were written in the percentages of the elements, instead of their compounds, it is thought that the chemical relations' between the different rock species and varieties would be more clearly apparent than at present, as Nordenskiold has shown for the meteoric peridotites.* From the manner in which many chemical analyses of rocks have been made (poor work, poor specimens, and no knowledge of the rock) the difficulties in the way of proving these relations are great; but the writer has prepared tables which show them in an approximate manner. * Nature, 1878, xviii. 510, 511; Geol. FSren. Forhandl., 1S78, iv. 45-61; Zeit. Deut. geol. Gesclls., 1881, xxxiii. 14-30. SCHEMES OF CLASSIFICATION THEIR RELATIVE VALUE. 33 SECTION V. Classification based on Mineral Composition. IF the artificial schemes of lithological classification are examined, it will be found that they are generally based on the mineral composition, the geological age, and the structure of the rocks, some rocks even being defined by a statement of that which they are not, or that which they do not contain. It does not accord with the limits of this paper to enter upon any thor- ough critical discussion of the application of such principles, but a certain examination of them may be made, so far as they bear on the method of classification it is proposed here to use. Amongst the minerals of which the chief use is made in classification there may be mentioned the feld- spars, including leucite and nephelite, also olivine, quartz, the micas, pyrox- enes, and the amphiboles; although siny mineral is liable to assume in special cases sufficient importance in these artificial schemes to found specific distinctions iipon. Of these minerals the most important are the feldspars, and on their presence or absence, and on the species or type of feldspar present are founded some of the most important divisions of the rocks. In order to successfully use any mineral in classification it is necessary that it should be a determinate quantity that is, it should always have in the rock one mode of formation only that its specific limits shall be well marked, and that it shall be accurately determinable with fair facility. The Feldspars. That the feldspars originate in all three of the methods given previously for the origin of rock minerals foreign, indigenous, and secondary the writer thinks cannot be denied ; although, for the most part, they appear to be indigenous. In classification of this kind, the most important question about the feldspars is, what are their divisions and the diagnostic characters of them. A sketch of the various prominent opinions regarding their constitution will best answer our question. In 1846 Schoerer held that the feldspars were different grades of satura- tion, of a radical compounded of equal atoms of R. and Al.* Later he remarked t that it was permitted to regard all known feldspars as chemical Ann. Physik Chcmie, 1846, Ixviii. 337; Am. Jour. Sci. 1848 (2), vi. 61. f Ann. Physik Cliemic, Ixxxix. 19. 5 34 CLASSIFICATION BASED ON MINERAL COMPOSITION. combinations of either (1) anorthite and labradorite, or (2) anorthite and albite (orthoclase), or (3) labradorite and albite (orthoclase). In 1850 Delesse said : " I have already had occasion to remark that we have hitherto attached too much importance to the varieties of the feldspars of the sixth crystalline system, and that nature has not always been limited by the divisions established among them by chemists and geologists ; the same rock sometimes containing several varieties of these feldspars." In the last reference Delesse had also pointed out that the composition of the feldspar was not constant even in the same rock from the same locality. In 1851 Hermann taught that in the feldspars were two molecules : one denoted by a = (R Si 3 -j- Si s ), and the other by b = (R Si -f- Si). Of these molecules the species were thus compounded (giving, however, from his list only those species of importance to-day) : Orthoclase = a Albite = a' Anorthite = b . , . a + b Andesite 2 T,:iVn*nrlnritp 1 O L a -j- o o Oligoclase = 5a + 3b The union in this case was regarded as a molecular union, and not a chemical combination between the atoms, f Sartorius von Waltershausen, in his work " Ueber die vulkanischen Gesteine in Sicilien und Island, und ihre submarine Umbildung," published in 1853, advanced the theory that there were three definite triclinic feldspars, i. e. anorthite, albite, and krablite, and that the other triclinic feld- spars were formed by varying compounds of these. Krablite, or baulite, J was then supposed to be a definite silicate, with the atomic ratio 1:3: 24, as determined by the researches of Forchhammer and Genth ; || but it has since been shown to be a mineral aggregate or rock, referred at first to the * Bull. Soc. Ge"ol. Prance, 1850 (2), vii. 526 ; sec also Ann. Mines, 1847 (4), xii. 266, 267 ; 1849, xvi. 327, 32S. f Jour. Prakt. Chemie, 1851, lii. 256-258. $ Landgrebo, Minerulogie der Vulcane, 1870, pp. 60, 227. Oversigt over det Kgl. danske Videiiskaberues Selskabs Forhandliiiger, etc., 1842, pp. 43-55 ; Jour. Prakt. Chemie, 1843, xxx. 394. || Ann. Chemie Pharm., 1848, Ixvi. 271. COMPOSITION" OF THE FELDSPARS. 35 quartz trachytes,* and later to the liparites or rhy elites, f which now include most of the quartz trachytes of the older authors. Bunsen, indeed, maintained both before and after 1853, that baulite was a mechanical mix- ture a rock, and not a mineral, t In 1854 Dr. T. Sterry Hunt stated that the triclinic feldspars constituted a genus, of which albite might be taken as one representative, and anor- thite as the other. The intermediate feldspars might be distinct species, or they might be looked upon as variable mechanical mixtures of the two typi- cal feldspars, albite and anorthite. A similar mixture of albite with a potash feldspar, and anorthite with a soda or magnesian one, as well as of orthoclase with a lime or potash feldspar, were regarded as probable. Hunt distinctly objects to any idea that these variable feldspars were formed by chemical unions between the different types, and makes it clear that he had in rnind the process of envelopment and variable, " mechanical, contemporaneous intercrystallization, on which he founded his doctrines of the origin of crystalline rocks, pseudomorphism, and metamorphism. In this he fol- lowed Scheerer's views regarding the relations of iolite and aspasiolite, and of olivine and serpentine. The proportions of these intermixtures of the feldspars were regarded by Hunt as entirely variable and indefinite, being " such mixtures of species as constantly take place in the crystalliza- tion of homoeomorphous salts from mixed solutions," and he explained the process in every case in the same way as he did in the case of perthite. That this view of the mixture of the feldspars is the same as his explana- tion of pseudomorphism can be seen from his statement that the latter has resulted in many instances from the association and crystallizing together of homologous and isomorphous species. In 1864 Professor Gustav Tschermak advanced the theory that (excepting bvalophane and danburite) there were three distinct species of feldspar: Orthoclase, or potash feldspar; Albite, or soda feldspar; and Anorthite, or lime feldspar. He held that soda and potash were not isomorphous, and therefore all orthoclase crystals containing soda were mechanical mixtures Zirkcl, Sitz. Wien. AkacL, 1863, ilvii. (1) pp. 243, 244; Lehrbuch der Petrograpliie, 1806, i. 25; ii. 151-166. f Zirkel Die mikroskopische Beschaffeuheit der Mineralieu imd Gesteiiic, 1873, p. 341. J Bunsen Ann. Pliysik Ciiemie, 1851, Ixxxiii. 199, 201; Ann. Chemie Phann. 1854, Ixxxix, 98; Preyer imd Zirkel, Reise nach Island im Summer, 1860 ; pp. 317-324. Proc. Am. Assoc. Adv. Sci., 1854, viii. 237-547; 1S71, xx. 1-59; Am. Jour. Sci., 1853 (2), xvi. 218; 1864, xviii. 270, 271 ; 1'liil. Mag., 1855 (4), ix. 354-303; Geological Survey of Canada, Report of I'mirn M, 1 vV'i. |i|i. 3;:i-:',v; ; 1838, p. 180 ; Canada in the London International Exhibition, 1862, p. 05 ; Geology of Canada, 1803, p. IMI. 36 CLASSIFICATION BASED ON MINERAL COMPOSITION. (interlarainations or intercrystallizations) of orthoclase and albite. Albite and anorthite were looked upon as two distinct species of triclinic feldspar, and it was held that labradorite, andesite, and oligoclase were formed from isomorphous mixtures of albite arid anorthite, that is, through the mo- lecular union of albite and anorthite, in definite mathematical propor- tions. These mixtures Tschermak distinctly held were not mechanical, but molecular. The finding of potash in the triclinic crystals formed from the molecular union of albite and anorthite was explained by Tschermak, by the supposi- tion that some orthoclase was mechanically interlaminated. Oligoclase, labradorite, and andesite were united under the name of plagioclase. This term has, however, been employed since to include both albite and anor- thite, and in this latter sense it is generally used.* Tschermak, indeed, does not claim this theory to be entirely original with himself, for he remarks, " Dabei verschweige ich jedoch nicht, dass die Grundidee dieser Vereinfachung keineswegs neu sei und ich bemerke, dass durch die friiheren Bemiihungen der Forscher, welche eine solche Vereinfa- chung auf chemischer Basis anstrebten, also durch Sartorius von Walters- hausen, Rammelsberg, Scheerer, der Gedanke endlich so weit entwickelt wurde, dass Andere wie Delesse, Hunt denselben als keines speciellen Beweises bediirftig hinstellten." Tschermak's theory was variously opposed and advocated, and on one side or the other the most prominent chemical mineralogists arranged themselves. It has been especially discussed by Rammelsberg, Rath, Roth, Bunsen, Peterson, Streng, and others, with the result that it is the generally accepted view regarding the composition of the feldspars. Tschermak's theory does not appear to be well understood in England or America, and although the present writer recognises his liability to also misinterpret it, he deems it right to point out some of these differences of opinion, believing that in the end it will lead to a more accurate conception of the theory than now seems to exist. Streng later offered a theory for the feldspars, in which he held that they were silicates, in which the Ca partly replaces the Na 2 , and R the Si 2 ; claiming that there were only two principal divisions; 1st, the potash feld- spar, and 2d, the lime soda feldspar the latter forming a number of varie- ties with variable composition.! * Sitz. Wicn.Akad., 1864, 1. (2) pp. 566-613. f Neucs Jalir. Min., 1865, 411-434, 513-529; 1871, 598-618, 715-731. TIIK FKI.IKSPAKS .- TSCHKKMAK'S THEORY. 37 Petersen objected to Tschcrmak's theory on the ground that orthoclase feldspars containing soda do not show any of the striations peculiar to tri- clinic feldspars, which, if the theory is correct, must be mechanically mixed with the soda-bearing orthoclase; also, that some potash-bearing plagioclases exhibit no trace of orthoela.se.* Professor J D. Dana, in 1867, also opposed Tschermak's theory, holding that the variations from the normal analyses were caused by, (ft) Incorrect analyses. (6) Impurities; and often, mixtures of different feldspars through inter- crystallization. (c) Alteration ; caused either (1) by the infiltration of ordinary waters, carbonated or not the rocks containing feldspars having been exposed to this action through long ages past or (2) through the same process aided by mineral ingredients in the waters, resulting in the introduction of mag- nesia, oxide of iron, etc., and in other changes.! In the meanwhile Tschermak's theory assumed great prominence, and in 1874, Dr. T. Sterry Hunt put forward the claim that he was the originator of it. In support of this assertion he quoted from a published abstract of his original paper (mtlc, p. 35), which had given his views in an indefinite manner, and in his direct quotation from this abstract a hypothetical state- ment was altered to a positive one. t As pointed out in the preceding pages, Hunt's theory of the triclinic feldspars is nearly the same as Dana's (b) given above. Hunt held that they were indefinite, variable, mechanical aggregates, or intercrystallizations; while Tschermak held that they were formed by isomorphous molecular unions in definite proportions. Further, Hunt's theory does not seem to be at all original with him. Yet a number of writers have acknowledged Hunt's claim, presumably because they have never read his original papers, or else have misunderstood Tschermak. The use of the term " mixture " with two distinct meanings 1st, for mechanical aggregation (Hunt), 2d, for molecular combination (Tschermak) has probably added to the confusion. * Xcnes Jnhr. Min., 1872, pp 576-586 ; Jour. Prakt. Chemie, 1873 (2), vi. 200-212. t AIIIIT. Jour. Sci., 1867 (2), xliv. 200, 399. See also System of Mineralogy, 5th cd., 1868, p. 336. t Chcm. Gcol. Essays, pp. 4-3S, 4~ti5. 38 CLASSIFICATION BASED ON MINERAL COMPOSITION. Amongst those who have acknowledged Hunt's claim are both Danas,* Silliman,f Leeds, $ Rutley, Hawes, || and Fouque and Levy. ^[ Edward Dana says that the theory " was offered by Hunt, and has since been developed by Tschermak ; " Rutley, that Hunt's conclusions are almost identical with those of Tschermak ; again, James D. Dana, mistaking Hunt's views, stated of the latter, " In the view . . . with regard to the molec- ular relations of the feldspars, he appears to have anticipated Tschermak by ten years ; " while Silliman goes so far as to say, " Here will be found devel- oped his [Hunt's] views on the constitution of the feldspars, which were some years later adopted without acknowledgment by Tschermak." Leeds appears to have been the only one who recognized the essential difference between the indefinite mechanical-mixture view adopted by Hunt, and the definite molecular-union theory of Tschermak ; but he failed to see the logical conclusion to be derived, that Hunt** was in no sense the originator of Tschennak's theory, and that all the charges of appropriation made against the latter ought to be entirely withdrawn. In 1875, Descloizeaux, from the optical properties of the plagioclastic feld- spars, concluded that andesite was an altered oligoclase, but that labradorite and oligoclase are distinct species, and not isomorphous mixtures. He looked upon their optical properties as opposed to Tschennak's theory .tt To explain the chemical composition, Descloizeaux calls attention to the theory of Friedel and others, that the several feldspars differ from one another only in their proportions of silica, forming a series whose common difference is Si0 2 : e. ff., anorthite -j- Si0 2 = labradorite ; labradorite -j- Si0 2 = andesite ; andesite -f- Si0 2 oligoclase ; and oligoclase, -}- Si0 2 = albite. While Descloizeaux admits that the composition of the feldspars may be explained as well by Tschermak's theory as by Friedel's, yet he holds that the latter accords better with the optical and crystallographic characters of the species. Vom Rath, on the other hand, is of the opinion that the chemical consti- tution of the feldspars is most satisfactorily represented by Tschennak's theory, and holds that the formation of the intermediate triclinic feldspars * Am. Jour. Sci., 1875 (3), ix. 102 ; Text Book of Mineralogy, 1877, p. 297. t Amcr. Chemist, 1&74, v. 106. J Amcr. Chemist, 1877, vii. 335. The Study of Rocks, 1S79, p. 95. || Geol. New Hampshire, 1S7S, iii. parti, p. 89. 1[ Miner. Microg., 1879, p. 200. ** Bull. Mus. Comp. Zool., 1881, vii. 370-374, 443-454, 458, 459. ft Ann. Chimie Physique, 1875 (5), iv. 429-444; Comptes Keudus, 1875, kxx. 364-371; Neues Jahr. Miu., 1875, pp. 279-284, 395-399. THE FELDSPARS: THEIE COMPOSITION. 39 by the molecular union of albite and anorthite is an established law, and not a mere hypothesis. He states that the supposition that the difference of composition in the plagioclastic feldspars is due to the successive addi- tion of silica molecules, takes no account of the replacement of lime and soda, which is so intimately associated with the variation in the amount of silica. Andesite, he holds, is distinct from oligoclase. In 1876,* Descloizeaux described a new potash feldspar (microcline) which is tricliuic, although chemically the same as orthoclase. This dis- covery only added to the difficulties and confusion in the feldspar question. Mallard and Michel Levy, however, taught later that orthoclase and micro- cline were the same, but that the cross-twinning had become so fine that it was no longer visible in polarized light, i. e., the laminae were excessively thin so much so as to cause the feldspar to appear optically homo- gcneous.t Extended observations were later made by Max Schuster on the optical characters of the feldspars. He claims that these characters show a gradual change or transition between anorthite and albite, pan passu with the varia- tion in chemical composition ; that is, each definite proportion in the mix- ture of anorthite and albite gives a variety whose optical properties approach one or the other of these feldspars, according to the predomi- nance of either. From the optical characters of any feldspar crystal, there could be inferred its chemical composition, and the reverse. He claims that Tschermak's law is sustained by these observations, and such seems to be the prevalent opiuion.J These observations of Schuster are in accordance with those of Sennamont on Rochelle salts. They not im- properly may lead to very different views of mineral species from those commonly held. From the above, it seems clear that the feldspars are either species with such indefinite boundaries that they (the feldspars) cannot be defined with any accuracy, or else they form a continuous scries from anorthite to orthoclase. In either case it is improper to found definite groups and specific divisions of rocks on a variable and indefinite group of minerals, concerning whose nature the chemical mineralogists are not agreed. C'omptcs Rendus, 1870, kxxii. 885-S91 ; Ann. Cliimie Physique, 1876 (.')), ix. 433-499. f Bnll.Min.Soc. France, 1^79, pp. 133-1:59 ; Neucs Jahr. Min., 1880, i. pp. 17-4,175; Zcit. Krvst., 18SO, iv. 632, 633. t Sitz. Wien. Akad., 1S79, Ixxx. (1), 192-200; Miu. MittU., 18SO (2), iii. 117-284. Ann Chimic Physique, 1851 (3), xxxiii. 429-437- 40 CLASSIFICATION BASED ON MINERAL COMPOSITION. Even supposing the species were well established, have we any methods whereby these species or divisions can be positively discriminated ? In 1876, Descloizeaux gave a method, whereby he thought the differ- ent plagioclastic feldspars could be distinguished from one another. This method required a thin transparent section, either cleaved or ground par- allel to the plane of easiest cleavage (0, OP, 001, p) the triclinic feld- spars being as a rule twinned, so as to show color bands parallel with the plane of the next easier (or less perfect) cleavage. The sections are placed on the stage of the polarizing microscope, with the color bands parallel to any diagonal of the crossed nicols (plane of vibration or plane of polarization) ; the section is then revolved until one set of color bands becomes dark, or the light is extinguished in them. The angle between this point and the former position of the section is taken. The section is then revolved in the opposite direction xintil extinction of light takes place in the alternate set of color bands. The angle between this point and the first or original position of the section is taken. If the section is properly cleaved, or ground, the two angles observed are equal. By experiment on feldspars of known composition, the angles between the nicol diagonal and the extinguished color bands, or the angle (double the others) between the two positions in which the alternate bands are rendered dark, have been determined ; and it is assumed that all feld- spars having the same angle of extinction as any one of these previously determined angles belongs to the same species of feldspar. Descloizeaux held that this supposed fixity of optical characters was opposed to Tscher- mak's theory.* Prof. R. Pumpelly endeavored to make Descloizeaux's method practi- cally applicable to thin sections of rocks, which he did in the following manner : If instead of cutting sections parallel to the principal cleavage they should be cut at any angle with that cleavage but in the zone : l(p:h'; 001: 100; OP: co P oo) we should have every variation of angle, from up to the maximum for that feldspar. In a thick rock sec- tion in which the feldspars are cut at random, it is necessary first to ascer- tain whether any feldspar section has been cut in the zone : ii. This is done by ascertaining on trial if the extinction in the alternate color bands takes place at equal angles on opposite sides of the nicol diagonal. If it does, the section of feldspar was cut as required. A number of such sections * Comptcs Rendus, 1876, Ixxxii. 8S5-891 ; Ann. Chimie Physique, 1876 (5), k. 433-499. TIIK m.DSl'ARS: THEIR DETERMINATION. 41 are usually to be found in the slide, and their maximum angle is taken as the index of the feldspar. In actual practice, Professor Pumpelly took as oligoclase those feldspars of which several individuals in a rock section rave angles between 32 and 36; as labradorite, those between 36 and 62 ; and as anorthite those over 62. When more than one feldspar is present in the slide, only that one can be distinguished which has the highest angle ; and this may be the minor or subordinate feldspar. It is even possible for a single crystal, only, of one feldspar, to change the conclusion as to the rest of the feldspars in the sec- tion. Then, again, the sections examined may be so cut as to give a lower angle than they should ; therefore the observer concludes he has a different feldspar from the one actually present. It is scarcely possible by this method to distinguish between oligoclase and albite.* Professor Pumpelly was, however, anticipated in order of time, in the publication of this method, by M. Michel Levy, who discussed the subject mathematically, and applied the principles to many different minerals.! That the work of both Levy and Pumpelly was independent and original with both, can be inferred from the fact that the latter asked me early in the year 1876 to undertake a mathematical discussion of this subject, in order to aid his experimental work which he was then upon. The mathe- matical portion the present writer had then neither time nor inclination to perform, but the practical work of Professor Pumpelly resulted in that method of determination which has been given before. Schuster's results would, however, appear to render such determinations of but little value at present. Dr. George W. Hawcs in 1881, showed that the common method of distinguishing triclinic from monoclinic feldspars was unreliable in certain cases; for labradorite from St. Paul's Island and Canada, anorthite from New Hampshire, and oligoclase from Bodenmais, exhibited none of these supposed distinguishing features, i. e. striation in common and polarized light. J Amongst the methods used for the determination of the feldspars, as well as of other minerals, is the micro-chemical method of Dr. E. Boficky, which consists essentially in subjecting the specimen to the action of lluo- silicic acid, hydrofluoric acid gas, chlorine gas, etc. ; and microscopically Proc. Am. Arad. Sci., 1S78, xiii. 253-309; Geol. AVi>r., ISM), iii. 30. f Ann Min,-, \^',1 (7), xii. 31)2-10!); Comptcs Remlus, 1878, kxxvi. 316-348. J 1'r.c Nat. MILS., 1S8I, pp. 134-136. G 42 CLASSIFICATION BASED ON MINERAL COMPOSITION. examining the crystals produced, under proper conditions. This is simply a method of making qualitative tests upon material in bulk too small to be tested in the ordinary way.* In 1876 Professor J. Szabo published! his method of determining feld- spars by means of their fusion, reactions, and coloration produced in the Bunsen flame, which gave, according to him, a means for estimating the percentages of alkalies, etc., in the specimen examined. Still a third method is from the crystals formed in blowpipe beads under proper conditions. This method was invented by Mr. George H. Emerson in 1863, t and later expanded by Gustav Rose, W. A. Eoss,|| and H. C. Sorby.^j The results are essentially similar to Boricky's method, qualita- tive, but can be used with small fragments. The last and most important method is that of separating the feldspars by means of liquids of different specific gravities. In this way considerable material of a certain specific gravity can be obtained for chemical analysis, and its nature ascertained.** All these methods have their defects : as, for instance, the feldspars which give character to the rock are of more than one species, usually ; they contain more or less glass and mineral impurities ; and they are subject to alteration. These factors change their specific gravity and chemical relations, and make the determination of a few crystals of but limited value in fixing the condition and character of the remaining feldspars. Of all the methods the specific gravity one promises the most, but it is not believed at present to lead to any essentially valuable results in determining minerals like the feldspars, whose very species are so inde- terminate. While the before-mentioned methods, and many others not mentioned, have added greatly to the knowledge of minerals, they seem to have blinded most observers to the general characters of the rocks they were studying. In the coarsely crystalline rocks crystals of feldspar, of sufficient size for analysis, can often be obtained ; but that analysis, to be of any value, must proceed on the supposition that the crystal is pure, unaltered, and * Archiv der naturwisscnscliaftliohcn Landesdurchforschung Bolnnens, 1877, iii- 5t1i Abtli., pp. 1-SO. f Ueber erne neue Methode die Feldspatlie aucli in Gcsteiucu zu bestimmen, Budapest, 1876. J Amer. Jour. Sci., 1804(2), xxxvii. 414, 415 ; Proc. Am. Acad., 1865, vi. 476-494. Moiiatsb. Berlin Akad., 1867, pp. 129-147. || Chemical News, 18G8 (Amer. Reprint), ii. 74-76, 147, 148, 157-100, 196 ; Pyrology or Fire Chemis- try, London, 1875. f Month. Micro. Jour., 1809, i. 349-352. ** Tlioulet, Comptes Rendus, 1S78, Ixxxvi. 454-456; Bull. Min. Soc. France, 1879, p. 17; Church, Min. Mag., 1877, i. 237, 238; Goldschmidt, Neues Jahr. Min., 1881 (Bcilagc-Band), pp. 179-238. THE FELDSPARS AS A BASIS OF CLASSIFICATION. 43 typical of the predominating feldspar in the rock ; microscopic analysis shows that the larger crystals in our rocks are generally abnormal, often foreign to their present surroundings, containing numerous inclusions, some- times three fourths of the crystal being glass, microlites, etc. If a thin section is prepared before the chemical analysis is made, it only proves that the part examined is pure or impure, as the case may be, offering no proof regarding the rest, only a probability ; further, the larger crystals are usually the subordinate ones, being unlike the generality in the mass of the rock. This method is, also, inapplicable in the cases where it is most needed ; in the fine-grained and compact rocks, which contain few or no feldspars of sufiicient size. The larger feldspars are most subject to alteration, passing from the basic towards the acidic,* some becoming greatly changed while the smaller crystals are untouched ; yet the analyst names the rock from the altered, and not from the unaltered feldspar, euphotide, for instance.! The secondary formation of feldspars, like orthoclase in rocks, adds greatly to the difficulty of making the classification dependent upon the kind of feldspar present. In other cases the feldspathic material is seen to be largely replaced by quartz and other minerals the presence of the first not being suspected until the crystal was examined under the micro- scope. The twinned character of the triclinic feldspars, seen both in com- mon and polarized light, is not a constant character, as has been pointed out before. It has been customary to regard all unstriated feldspars in basic rocks as plagioclase, cut parallel to the brachypinicoid, but in the acidic rocks as orthoclase. Through the great alteration to which the feldspars have been subject in the older rocks, all signs of twinning have been frequently obliterated, thereby causing such crystals in granitoid rocks to be classed as orthoclase. J The chief value, therefore, of the optical method for distinguishing the feldspars is apparently to deter- mine the predominance of plagioclase, or of orthoclase ; while the chief use of the present micro-mineralogical study of the feldspars in lithology is the determination of the more or less acidic or basic composition of the rocks, according to the predominance of orthoclase or plagioclase in them. From the above it follows that a systematic classification cannot be properly based on any such variable, indeterminate materials. * Gco. TV. Hawes, Geology of New Hampshire, iii. part. iv. 90-92. f T. Stem- Hunt, Am. Jour. Sci. (2), ]859, xxvii. 336-319 ; J. D. Dana, ibid. (3), 1878, xvi. 340. J Bull. Mus. Comp. Z.M.I., 1880, vii. 55, 56. 44 CLASSIFICATION BASED ON MINERAL COMPOSITION. The Pyroxcne-Amiiliibole Groups. In the ens.tatite-hypersthene-pyroxene-amphibole group of minerals, a similar relation seems to exist as in the feldspars, and a like variability. In these the distinctions are founded mainly on optical, crystallographic and cleavage characters. May there not be a similar relation between the orthorhombic and monoclinic pyroxenes as there is between the different feldspars ? Specific distinctions between rocks have been based solely on a difference in cleavage in minerals otherwise identical. This is the case with augite and diallage, which thus become the means of separating diabase from gabbro. How valid this cleavage distinction is, may be learned from the fact, that the cleavages of augite and diallage are found sometimes united in a single crystal of pyroxene. While augite has been regarded as distinctive of the augite-andesites, basalts, and diabases, more recent observations show that it is not confined to any one species of rock, but exists in every species, from the pallasites to the rhyolites. So, too, it was regarded as entirely characteristic of modern or younger rocks, but this is found not to be true. This belief in the occurrence of augite in modern rocks has arisen mainly from its ready alteration to viridite, chlorite, hornblende, biotite, etc., which would thus cause it nearly or entirely to disappear in the older and more altered rocks. Again, the probability that pyroxene in some of its varietal forms, like sahlite, is of secondary origin, increases the difficulty of employing pyroxene as a species character. In the case of hornblende but little distinction is made in nomencla- ture, whether the mineral is foreign, original, or secondary ; but in all these modes of occurrence it is given equal value in classification. As a foreign product it occurs in the andesites, the augite apparently arising from the crystallization of the dissolved hornblende material, while in the older forms of the same andesites hornblende occurs as a secondary product, after both the foreign hornblende and original augite. But the same rock is given three different names, according to the predominance of augite, foreign hornblende, or secondary hornblende. This is done, however, uncon- sciously by lithologists, since they do not practically make these mineralog- ical distinctions. The writer has seen two sections taken from the same hand specimen; one of which pronounced the rock a diabase, the other a diorite. TIIF. MIXERALOGICAL NOMENCLATURE OF ROCKS. 45 Of other minerals, mica occurs in a series of species like the feldspars, and in rocks is found in all three forms foreign, indigenous, and second- ary ; while chlorite and epidote are probably always secondary. From this it would appear that they are not suitable to designate species. Mincralotfical Nomenclature of Rocks. As the result of my study, I have been obliged to regard classification based on mineralogy, unless it be for some varietal subdivisions, as impracti- cable, because it is not a natural but an artificial method ; a system that requires constant change and readaptation ; and further, one that is based too much upon theory, individual judgment, and weight of authority; a system that admits, even requires, the "dumping" of rocks into certain places without the slightest regard to their relations of any kind, except it be that they hold one or at most a few minerals in common. This rela- tion is often vitiated by the observer's not taking into account whether these minerals are natural crystallizations in the rock, foreign, or secondary products. When classification is based on structure it usually separates the rock into distinct species according as it is glassy, partly glassy, crystalline, or porphyritic. That these distinctions are valueless, the writer thinks, fol- lows from the fact that the same rock mass may show all these cases ; dikes often being glassy and non-porphyritic on the edges, and crystalline and porphyritic towards the middle. The granitic structure indicates pro- bably a certain depth at the time of crystallization, but that this may practically be slight has been shown by the lava flows of Keweenaw Point, some of which are fine-grained on the surface, and coarsely crystalline (granitic or diabasic) towards the base. SECTION VI. Naming Rocks according to the Geological Age. Tins question has been so well discussed by Allport,* Dana t and others, that but little needs be said upon the subject here. Chemical, microscopi- cal, and geological evidence all point to the fact that this division is not a natural one ; and so far as my work has gone, the original characters of the Geological Magazine, 1S71 (1), viii. 249; 1S75 (2), ii. 583; Quart. Jour. Geol. Soc., 1874, xxx. 529. t Amer. Jour. Sci., 1S78 (3), xvL 336. 46 NAMING ROCKS ACCORDING TO THEIR GEOLOGICAL AGE. rocks are the same from the earliest times to the present. Other things being equal, the older rocks are more altered ; but as other things are not equal, no abrupt line can be drawn at the tertiary age, as is now generally done ; no characters exist whereby it can be done, and the line must remain an arbitrary one. Alteration produces characters in the rocks that can be used to indicate their greater age, or greater alteration terms which are not synonymous, although usually taken to be. The subject can, perhaps, be best formulated as follows : all rocks upon the earth's surface undergo alteration, and when exposed to the same conditions this is proportionate to the age. It is the unquestioned duty of the petrographer to study these changes, and starting from the least altered rock trace the continuous series to the most altered one of that kind. Such a system of work has been attempted here, so far as time and means have permitted. The presence or absence of fluidal cavities, which has been urged as a distinction between tertiary and pre-tertiary rocks, seems to be related more "to depth, and the conditions to which the rocks have been exposed since consolidation, than to age. The modern volcanic rocks are but the froth of an eruption, compared with the massive eruptions that have taken place in past time. The specimens collected are generally of a surface nature, and would allow the very ready escape of the inclosed vapors ; while at some depth the escape could not take place as readily. Our older rocks have in general suffered more denudation, and therefore are more likely to contain fluid inclusions. Should it be shown that these fluid cavities are in part, or entirely, of posterior formation to the rock, as has been urged by Vogelsang,* and shown by Julien to be so in one case,t it would require a new interpretation to be placed upon these and upon their occurrence. My work would indicate that while part of the fluidal cavities are origi- nal, some are posterior to the consolidation of the rock. A more fatal objection to their use in separating tertiary from pre-tertiary rocks is the finding of fluidal cavities in undoubted tertiary and post-tertiary rocks. $ Why quartz should be the mineral chosen to found this distinction upon, and other minerals containing fluid inclusions in lavas should be ignored, is a difficult thing to understand. The older rocks are, as a rule, entirely crystalline/ a condition arising in * Philosophic der Geologie, p. 155. t Am. Quart. Microscopical Jour., 1879, i. 103-115. H. C. Sorby, Quart. Jour. Geol. Soc., 1858, xiv. 484 ; Franz Zirkel, Microscopical Petrography, vi. 142, 156, 157, 104, 106, 167, 170, 205; Zeit. Dcut. geol. Gcsell, 1S68, xx. 117, 132. METHODS OF CLASSIFICATION. 47 part from the alteration of the non-crystalline materials, and in part from the fact of the more or less denudation which they have suffered. When Iniried enough to allow of a more or less slow solidification, the tendency is to form a completely crystalline structure, approaching more and more to the granitic. While the chief portion of the granitic structure, like that scon in gabbros, some diabases and diorites, true granites and syenites, is indigenous, all does not seem to be so, and great depth does not appear to be indispensable ; the only requirement seems to be slow solidification. SECTION VII. MdJiods of Classification. THE framework of any descriptive or systematic science is its classifica- tion, and upon it depends much of the value and suggestiveness of the work. It hence becomes a most important and vital point that the classification used shall be as correct as possible. The common classifications of rocks are well known to be artificial, and the writer has found them unsatisfactory in his work. Instead, therefore, of endeavoring to invent a new one, he has striven to discover the laws and principles of the natural system, so far as the rocks studied might enable him to do so. In studying rocks by any system, two methods are open to the observer. One is to simply describe the characters of the minerals in the rock, thus making the minerals the principal object, and the rock the subordinate one. In this case lithology becomes simply a mineralogical study, and the litholo- gist a mineralogist, who looks upon his rocks as small mineral cabinets, not realizing that the minerals are for the most part changing and changeable, and that the true method is to trace the history and variations of the rock as manifested in its mass and its constituents. The other method is to study the rocks for the purpose of determining their natural relations, the various changes they have undergone, and the characters by which they may be known in all these various alterations. In this the rock is the unit, the paramount object, and the mineral the subordinate quantity. From this point of view the minerals in a rock answer to the teeth and bones in an animal very important, but not superior in value to the animal as a whole. In a rock the mineral is the accident, it may or may not exist ; and when the rock is entirely composed of crystallized minerals, they should be used as the teeth and bones are used in determination, when the zoologist has them alone in his specimen in 48 A NATURAL CLASSIFICATION OF ROCKS. subordination to his general knowledge of animal structure. The subor- dinate relation of the mineral to the rock is more obscure than the same relation of the bones to the animal as a whole, since it is true that the mineral makes up the whole of the majority of rocks. The subordination of the crystalline minerals to the rock unit has been above thus strongly insisted upon since the opposite view seems to be taken by many litho- logists, who appear to study as microscopical mineralogists, instead of work- ing as lithologists proper. If it is possible to find the principles of the natural classification of rocks they ought to be applicable to any rock, whatever may be its age and condi- tion. By the natural classification of rocks is meant that system which will place together those forms nearest allied in their general characters, composi- tion, structure, and origin, when the rock as a whole is considered, and not certain of its characters only. The present artificial classifications of rocks pick out certain mineralogical characters, and render the rock characters sub- ordinate to them. These classifications are, to a certain extent, natural, and afford a convenient method of arrangement, requiring on the part of the lithologist who follows them simply skill in the determination of minerals. The method works well in some places, in others it masses together a most heterogeneous collection of rocks in a single species causing some rock names, like diorite for instance, to remind one of the old use of the term schorl in mineralogy. The employment of the minerals alone to determine the rock species is like Linnosus's use of the stamens and pistils in botani- cal classification a convenient but artificial system. One in objecting to the sexual system in botany does not reject the use of the stamens and pistils in classification, but he does object to their over-riding all other characters. They are to have their just and proportionate weight, but no more. So, too, in lithology the minerals in rocks hold a similar relation to them that the sexual organs do in plants they may comprise all or but little of the rock or plant. Minerals are entitled to their just and proportionate weight in rock classification but no more; they are not to be allowed, in my judg- ment, to become superior to the rock itself. No single character should be allowed to over-ride all the others, that is : the pi'esence or absence of a single mineral ought not to remove a rock from the species to which all its other characters assign it. In the current classifications it frequently hap- pens that the name given to the rock depends upon the particular portion of the hand-specimen from which the microscopic section was taken. MODERN METHODS OF CLASSIFICATION CHARACTERIZED. 49 The present lithological methods of classification can best be character- ized, in a homely way, by supposing that there were placed in the hands of a zoiilogist a great number of specimens of one species of some carnivorous animal, in every condition, from a fresh state to that of an advanced stage of decomposition ; also of those of the same species that had lived during distinct periods of time, as well as of those -that had lived for different lengths of time. With these, too, let there be given to the zoologist a number of packages of the bones of this animal, part of the bones having been worn and part nnworn. Now, imagine this zoologist naming as new species every specimen more decomposed than a preceding one ; as new species, those which showed different products of decomposition ; as new species, those that gave any variation, through that decomposition, upon chemical analysis as for instance, one and forty-seven one hundredths, or even nine-twentieths of one per cent. Continuing, let it be supposed that our zoologist makes new species, or at least varieties, out of all specimens in which he finds any teeth or bones of other animals which have been swallowed ; changing the species or variety as often as the inclosed fragments differ ; creating new species out of all that have lived for different lengths of time ; new species out of those whose bones are fractured crosswise, as distinct from those whose bones are broken lengthwise ; new species out of the distinct packages of frag- ments ; new species according as these fragments are worn or angular ; jilso, above and beyond all, fixing an arbitrary date, and demanding that all the specimens of this animal that had existed prior to that time should be held as distinct species, and in general of different origin from those that were of a later period. Suppose, too, that in addition, our zoologist should maintain that some, or all, of the animals submitted to him were made out of the remains of their defunct ancestors, by a species of fermen- tation ; also, that this creative chemical action was brought about by the deposition of the more recent remains upon the older, and that then the older forms successively came from beneath and lay down on top, thus pro- ducing a perpetual cycle. Let the reader suppose all this and he will gain some idea of the principles and methods commonly employed in lithology, as well as, in a greater or less degree, in chemistry as applied to rocks. This is no mere fancy sketch, but, so far as can be done by taking an illustration from a distinct science, shows some of the principles of lithology a< taught t/, and some of the methods upon which rocks, even now, are classified. 50 REMARKS ON CLASSIFICATION. Of course, every degree of skill exists in the applications of any classifi- cation, and many men, even with erroneous principles, succeed better than others do who work with correct ones. In this, however, it is a question of methods and not of men ; if it were the latter, then no discussion would be possible, since the older and more experienced would always, and justly, claim the right to have their views followed. Since it is a question of science and methods, it is often true that some young and fresh observer may, starting from the ground gained by others, push on a little way beyond them ; this too, when he ma'y not "have a tithe of the .ability of the others ; and it is not to be taken as presumption, if he endeavors to hold and point out the ground he thinks he has gained. The principles and methods employed herein were essentially enun- ciated by me in 1879,* the chief changes being the greater extension of the subject, owing to further investigations ; and these principles have been used by myself and my students in papers published since. Owing to the con- densed or abstract form of the first publication, it seems to have been but little understood by lithologists working in the mineralogical method of rock classification ; but it is hoped that the publications made since then, includ- ing this, will make my meaning sufficiently clear. One thing is certain, that unless a lithologist has had an extensive range of study of both the unal- tered and altered forms of rocks, and seen their relations in the field, such understanding will be difficult. Bearing upon this, it is to be pointed out that, outside of the rocks from a few volcanoes in Europe, every rock that I have seen from that country is altered, to a greater or less degree ; but the European classifications are chiefly based on such altered rocks. Hence, a mineralogical classification would naturally be adopted there, and will be tenaciously held to. A lithologist who is dependent on the material that Europe alone can furnish him, has not the means at his command of judging accurately regarding the basis of much of my work, which has been founded upon much fresher and less altered specimens than his. The most that I can hope to do, however, is to call attention to, and point out, that which seems a better way than the one at present followed. To perfectly express the natural system of rocks requires a universal knowledge of them a knowledge that it is not given to any man to possess. No definite scheme of classification can be laid down in the beginning ; it must result from the study of all available specimens, and be the best * Bull. Mus. Comp. Zool., 1879, v. 275-287- THE TRUE PRINCIPLES OF CLASSIFICATION. 51 arrangement according to their natural affinities that can be ascertained by that study. Future studies, discoveries of new rocks, and other causes are liable, in this science as in botany and zoology, to change the particular arrangement; but the principles and methods, so far as they are natural, will remain the same. The natural method is sufficiently elastic to allow of the incorporation of whatever new divisions future investigations may require ; it can never expect to be fixed and rigid, until the sum of human knowledge shall be complete. These changes will result simply in removing the artificial por- tions which imperfect knowledge has incorporated with it, and bring the classification nearer and nearer to the perfect natural system. If none of the system here adopted is natural, then all will in time be removed. The important principle that underlies the natural classification, as here advocated, is the belief that the older rocks now classed as disliiicl species are rocks that oiice were identical with their younger prototypes the present differences In in/I due to alteration, and conditions of crystallization. Standing next to this, is the belief in the chanc/cableness of the mineral con- stttnli'n) of the rocks, and the feeling that no classification should be placed entirely on so uncertain a foundation. As a deduction from the preceding discussion, the following statements may be taken as guides in describing and classifying our rocks : SECTIOX VIII. The Principles of Classification. 1. IK the study of rocks, we should begin with the younger and glassy state, and follow the gradations step by step to the most crystalline one in the series from the least altered to the most altered forms tracing every change, and studying their history in their tufaceous, poroditic, metamorphic, or any other state in which they or their remains can exist. 2. Any rocks that can be followed in this way between certain limits, whatever may be the changes they have undergone, form a species. In every shape they should be retained under the specific name ; the various modifications, when of sufficient importance, being regarded as varieties, and named as such. 3. All the petrological, lithological, and chemical characters should be used in determining rock species ; that is, the rock as a whole and in all its relations should be considered. 52 THE TRUE PEINCIPLES OF CLASSIFICATION. 4. The classification should be a natural one, therefore empirical, embody- ing all known characters of the rocks. A natural mineralogical classification of rocks is an impossibility, as it is based on part of the characters only characters which are unstable. Minerals may serve for the establishment of varieties, but not of species. 5. Geological age has no value in the classification of rocks, and is not to be employed except incidentally in varietal forms. 6. The addition of new names in any science, unless they are absolutely necessary for its advancement, is a detriment : the needed names should be taken from those now in use, so far as possible, and they should be employed, as nearly as may be, in their most approved sense ; when they belong to varieties they should be defined as such, and placed in their natural relations to the species of which they form a part. 7. In the classification of rocks, the original characters ought to hold priority over any of the secondary ones ; and they should give name to the rock, and decide its relations, so long as they exist in a determinable state. If necessary, or convenient, variety names or adjective terms can be added, to mark the special peculiarities of secondary or other origin but only in especially important cases. 8. If a rock is found to have the characteristics of any species as its prevailing characters, it should be referred to that species. 9. Chemical analysis alone, as a general rule, is insufficient to furnish data for naming a rock, since it is to be expected that rocks originating in different ways should have the same composition. 10. The relation of a rock to its associated rocks in the field is the principal criterion for determining its origin, especially in the altered rocks. 11. Association alone is an insufficient guide in determining the origin of a rock. 12. The origin of a rock should have an important bearing upon its classification. 13. The classification should be the exponent of some general law, which should embody all that is known at present of the rocks, and give promise for the future. CLASSIFICATION IN L1THOLOGY. GENERAL CONCLUSIONS. 53 SECTION IX. General Conclusions in Regard to Systems of Lithological Classification. THE general results and bearing of the preceding can be briefly summa- rized as follows : As is claimed for the organic world, so there is for the inorganic universe a universal law of evolution or development expressed by the phrases: ), 661-6/3. See also J. Lawrence Smith's Memoir on Meteorites, Aim. Rep. Smith. lust., 1S55, p. 158. SIDEROLITE. 67 the process takes place slowly and gradually. They appear to me to show that meteoric iron was kept for a long time at a heat just below the point of fusion, and that we should be by no means justified in concluding that it was not previously melted. Similar principle's are applicable, in the case of the iron masses found in Disco; and it by no means follows that they are meteoric, because they show the Widmanstatt's figuring. ]>il'l'cTciiee in the rate of cooling would serve very well to explain the difference in the structure of some meteoric iron [s], which do not differ in chemical composition ; but as far as the general structure is concerned, I think that we are quite at liberty to conclude that all may have been melted, if this will better explain other phenomena." * It would appear that these observers advocate the view that the sidero- litc-s must have been subjected to a long and slow cooling upon some body of sufficient size to yield the required conditions ; but since the same struc- ture can be developed in the iron of the stony meteorites, which show evi- dence of rapid cooling, the writer is compelled reluctantly to differ from these eminent observers, and to hold that while the Widmannstiittian figures may have originated as they have claimed, they may occur as readily in a small mass, cooling at a comparatively rapid rate, and therefore their origin is to be explained in some other way. In other words, as yet, there is no evidence that Sorby's and Tschermak's views are correct. It is probable that but few will claim that the siderolites of meteoric origin were formed by organic agencies. If they were not, it follows that the graphite contained in them could not have been so produced. This has a very direct and obvious bearing on the question whether the graphite in Azoic and other rocks need have been derived from animal or plant remains, and it negatives the supposition.! To make graphite the evidence of life is the same kind of argument as it is to claim that no oxides of iron and no carbonate of lime could be formed without the intervention of life. One we knew to be oftentimes of volcanic origin, and the other to be frequently the product of the decomposition of rocks. It is too much to assume, because minerals are known to form in certain conditions, or can be formed in certain ways, that they must always be made in that way. None of the meteorites now known appear to indi- cate that they came from a region where life could exist as we know it; hence, it does not seem proper to claim that life must have intervened in their formation merely because a mineral is found in them that is ordinarily supposed to be of organic origin. Nature, 1877, xv. 498. t J. Lawn-nee Smith, Mineralogy and Chemistry, 1873, pp. 284-310; Am. Jour. Sci,187fi (3), xi. 388- 395, 3-H2 ; Walter Flight, Pop. Sci. Rev., 1877", xvL 390-401. 68 THE SIDEROLITES AND PALLASITES. The term siderolite, or rather aero-siderolite was proposed by Professor N. Story Maskelyne, for the meteorites to which Gustav Rose had previously given the name pallasite. Rose afterwards divided his pallasites, retaining the original term for all, except two specimens, which he classed as mesosi- derites. These Maskelyne united again, but instead of using the term pal- lasite for all, proposed the name above given. The name pallasite belongs by prior right to these forms, while siderolite does not ; therefore, I trust Prof. Maskelyne will permit the transference of his term siderolite, as his own, from the pallasites to the forms that I have herein classed under the former name. It is impracticable to use the term sidcrite long ago pro- posed by Shepard on account of the well known mineral of the same name. The term holosidcritc, proposed by Danbree, is too inaccurate, since the majority of the specimens are not wholly iron. Siderolite (o-t'S^pos, \t0os) a stone of iron, or an iron rock seems to answer better than any other term for the specimens I have included under it here, and if the transference is permitted it will save the introduction of a new name.* SECTION II. Pallasite. THIS name was first given by Gustav Rose to a class of meteorites, of which he made the olivine iron rock of Krasnojarsk, Siberia, described by Pallas in 1776, the type. Later, Rose separated this group into two divis- ions pallasite and mesosiderite the latter comprising two specimens only.t The writer proposes to restore the term to its original use ; and in addi- tion, to place under it a few other meteorites and those terrestrial rocks that have a similar composition and structure. As in the case of siderolite, it is not intended to include any vein stones, but only original and eruptive rocks of this character and their derivatives. Of this group or species there will be given, first, descriptions of those nearest the siderolites in structure and composition, passing then to those nearer and nearer allied to the succeeding species peridotite. * Maskelyne, Phil. Mag., 1803 (4), xxv. 49; Rose, Monatsber. Berlin Akad., 1862, pp. 551-558; 1863, pp. 30-34 ; Shepard, Amer. Jour. Sci., 1807 (2), xliii. 22-28. | Monatsber. Berlin Akad., 1862, pp. 551-558; 1863, pp. 30-34; Abb. Berlin Akad., 1803, pp. 23-161. PALLASITE. 69 The Meteoric Pallasites. Tucson, Arizona. This meteorite is represented by two forms, known respectively as the Carleton and the Ainsa meteorites. The Carleton pallasite is composed of quite a compact sponge of iron, containing minute rounded grains of olivine (?) Some schreibersite in black angular grams also occurs.* The Ainsa pallasite is composed of a compact metallic sponge, the minute cells of which are filled by a white siliceous mineral in rounded grains. These grains are arranged in rude lines, giving to the iron an appearance somewhat resembling that produced by ttuidal structure. From the torn and broken surface of a specimen in Professor Whit- ney's collection a number of silicate grains were removed by a needle-point, imbedded in Canada balsam, covered and examined under the microscope. Most of the fragments present the optical characters of olivine, and some contain bubble-bearing stone cavities, arranged in irregular lines, the same as are the fluid cavities in quartz. A few of the broken grains presented the polarization characters of non-striated meteoric feldspar, but two fragments were seen which showed the polysynthetic twinning characteristic of pla- gioclase. Both of the above pallasites, when sawn or polished, present a more or less compact appearance, like the common siderolites, and it is only where the Ainsa meteorite has been forcibly torn apart, after being partially sawn, that its true structure can be seen. Since the sawn and polished surfaces of the irons are such poor guides to their structure, it may be that some other irons now classed with the siderolites belong here. While the silicates f of the Ainsa pallasites are nominally clear and transparent, a number of the fragments have been stained to a yellowish brown, owing to the oxidation of the iron. Hemalya, Tarapaca, Peru. This rock, as represented by a specimen deposited in the collections of the Boston Society of Natural History, is largely composed of iron, having irregular cavities filled with silicates, which are considerably decomposed in places. Mr. R. P. Greg states of a specimen in his possession, that its cavities were found to contain pure lead, a very hard, grayish-black, semi-metallic mineral, and a yellowish- brown one of an earthy texture, and insoluble in acids. Sometimes the lead only par- tially filled the cavities, but at others it entirely filled them, some being large as a pea.J The specific gravity of this pallasite was found to be about 6.50. Berdjansk, Russia. According to Hiriakoff, this is composed of an iron sponge, with fine grains of olivine and troilite, and on etching shows Widinannstattian figures. Specific gravity, 6.63. * Whitney and Brush, Proc. Cal. Acad. Sci., 1863, iii. 30-35 ; Haidinger, Sitz. Wien. Akad., 1863, xlviii. (2), 301-308. t Whitney, Proc. Cal. Acad. Sci., 1863, iii. 48-50. J Phil. Mag., 1S55 (4), x. 12-14. j Geol. Foren. Forhandl., 1878, iv. 72 ; Neues Jahr. Min., 1878, pp. 653, 654. 70 THE SIDEEOLITES AND PALLASITES. Deesa, Chili. This is composed of a compact iron sponge, containing inclosed silicates. Dr. S. Meuuier detected in it troilite, schreibersite, graphite, olivine, hypersthene, pyroxene, eustatite, chromite, etc. Specific gravity varies from 6.10 to 6.24, but no satisfactory analysis exists of it as a whole.* Atacama, Bolivia. The rock found in the Desert of Atacama, Bolivia, is described as a cellular or spongy, metallic mass ; the cells filled with granular, greenish-white olivine. The cellular spaces instead of being rounded, as in the other rocks of this species, are stated to be angular. An analysis of this rock as a whole is much to be desired, although a rough approxima- tion is given in the list of analyses. A correct chemical analysis would probably show this to be more basic than the Pallas rock of Siberia, f A specimen in the Harvard College Mineralogical Cabinet is probably from the same pallasite. This shows a very coarse sponge of iron, holding angular and rounded grains of olivine. The olivine is yellowish-green in color the yellowish tint owing in part to a ferruginous staining. The coarseness of the iron sponge allies this more nearly than any of the other pallasites seen, except that from Tarapaca, to the siderolites. On one side it shows a surface closely resembling an ordinary slickenside, hut on another side is to be seen the remains of a fused crust the common mark of a meteor- ite. Some pyrrhotite was seen in this rock. Figure 1, Plate I., is from a tracing made from the polished surface of this specimea Owing to the dulness of the polished face the polishing having been done many years ago it was impracticable to get the outlines exact. The general structure is well shown for the spongy metallic iron, hut the olivine grains are far more angular, as a rule, than the figure represents them to be. Specimens of an Atacama meteoric iron in the Mineralogical Cabinet, received from Professor I. Domcyko, show that this formed a metallic sponge holding olivine. Only traces of the olivine are left, and beyond it nothing can be told regarding the silicates that might have been contained in this sponge. Some pyrrhotite was seen. This con- tains less iron probably than the Pallas iron. Another specimen of Atacama iron in the same Cabinet, received from a Mr. Clay, of Philadelphia, is similar to that figured (PI. I. fig. 1), but the sponge is not so coarse, and the olivine is more abundant. This mineral is considerably decomposed, and the iron much oxidized. Biiburg, Prussia. A coarse sponge of iron, containing in its cells light-greenish-brown olivine. The only specimen seen by the writer somewhat resembles the Atacama meteorite, but, per- haps, contains even more iron. * Daubree, Comptes Rendus, 136S, Ixvi. 571, 572 ; Meuuier, Cosmos, 1869 (3), v. 552-556, 579-586, 612-019. f Traus. Roy. Soc. Ediu. 1831, xi. 223-228 ; Clark, Metallic Meteorites, 1851, pp. 17-19. PALLASITE. 71 Hommoney Creek, Buncombe Co., North Carolina. A coarse cellular mass of nickeliferous iron, with most of the observed cells empty but a few containing dull, yellowish-gray divine grains. The iron exhibits, on etching, Widmaimstuttiaii figures.* Singhur, India. The pallasite found at Singhur, Deccan, India, was from a basaltic hill. It is described as a vesicular mass of iron, with the cavities either empty or else containing "small, yellowish-white, earthy-looking bodies, about the size of peas" olivine (?). No satisfactory analysis of this rock has been made.f Its occurrence is similar to that of the iron from Disco, Greenland, and it may be of like terrestrial origin. Forsyth, Taney Co., Missouri. A white, sponge-like mass of nickeliferous iron containing greenish olivine, the latter being more abundant than the former.J Specific gravity, 4.46. Anderson, Hamilton Co., Ohio. This pallasite, which may properly be called the Little Miami meteorite, was found on an altar in one of the earthworks now being explored in Anderson Township, in the Lit- tle Miami Valley, Ohio. This was placed in the hands of Dr. L. P. Kinnicutt, for analy- sis, by Mr. F. W. Putnam, the curator of the Peabody Museum of Archeology, into whose possession it had come. The polished surface shows a coarse sponge of iron, holding, according to Dr. Kinnicutt, olivine, brouzite, and an unknown mineral. In the section figured in Dr. Kinnicutt's report, the iron appears to predominate over the silicates, but taking the mass as a whole the two form about equal bulk. In structure it closely resembles the Pallas iron, its oliviue grains being as a rule rounded, and not so angular as the Atacama pallasite. The olivine forms the chief portion of the siliceous material. The specific gravity of. the mass is 4.72. The etched surfaces show the Widmannstattian figures. Analyses of the iron and of the olivine were given by Dr. Kinnicutt, and from this a rough approximation is given of the composition of the mass as a whole, on the supposition that the iron and olivine form about equal portions of the mass. Since there was sufficient material it seems a pity that no complete analysis has been made. Krasnoj'arsk, Siberia. The Pallas rock is formed by a coarse metallic sponge, whose more or less rounded cavities are filled with olivine. This sponge-like structure, or one approaching it, is characteristic of the pallasites, so far as known. No complete analysis of this rock has ever been published that the writer can find, except an old one of Laugier, || in which the iron was estimated as an oxide. Shcpard, Am. Jonr. Sci., 1S47 (2), iv. 79-82. f Herbert Giraml, Edin. New Phil. Jour., 1849, xlvii. 30, 57. J Shepurd, Am. Jour. Sci., 1860, (2) xxx. 205, 2 nard held that the chondritic structure was different from any terrestrial form, and that it was produced through the projection of incoherent volcanic matter, which through its agglomeration formed the tufaceous-like meteorites. J Waconda, Milchel Co., Kansas. Some description of this meteorite has been given by C. U. Shepard and J. L. Smith. According to the latter it is composed of iron, pyrrhotite (troilite), olivine, and Phil. Mag., 1SC3 (-1), xxv. 50-58. f Mm. Mittli., 1873, pp. 1-8. J Mem. Soc. Beige Micros., 1879, v. 43-50. Am. Jour. Sci., 1876 (3), xi. 473, 474; 1877, xiii. 211-213. 94 PEEIDOTITE. pyroxene minerals. The specimens purchased for the Whitney Collection from Ward and Howell show an ash-gray groundmass, stained with brownish spots of rust, and con- taining grains of grayish-brown olivine. Section : a yellowish-brown and grayish groundmass containing iron. On one side a black band forming the exterior (rind) of the meteorite is preserved. The groundmass is composed of olivine grains with some enstatite. The yellowish-brown color is owing to a ferruginous staining of the silicates, while the rind is composed of the same minerals as the interior, but owing to the heat to which it has been exposed it has been burned black. Clear grains of untouched silicates (olivine and enstatite) are to be seen both in the interior and in the crust. lu one corner of the section a small amount of a fine ash-gray semi-base was observed cementing olivine grains. The mixed enstatite and augite with iron, and a ferruginous stained groundmass are shown in figure 4, Plate III. Goalpara, India. The Goalpara meteorite, according to Tschermak, is a dark-gray granular rock, having a porphyritic structure. In the deep-gray groundmass are inclosed clear colorless and yellowish grains. On microscopic examination the meteorite was found to be composed of enstatite, olivine, iron, and pyrrhotite. The enstatite shows well-marked cleavage-planes running in two directions, forming an angle of 92 with each other. The olivine has no cleavage, and does not occur in distinct crystals, but in minute grains united together. The groundmass in which the olivine and enstatite are inclosed is very fine-grained. Microscopically it is seen to be composed of minute transparent grains, apparently oliviue, and untransparent forms. These last are of three different kinds : iron, pyrrhotite, and coal-like bodies. The iron forms a sponge-like mass, with extremely thin cell-walls composed of cubic crystals. The coal-like bodies are described as being in all their properties similar to soot (graphite?). The groundmass is said to appear in branching, leaf-like, thread-like, and dot-like forms, winding between and around the grains forming the olivine clusters. The student is referred to Tschermak's paper for the complete description and figures illustrating the microscopic structure.* VARIETY. Lherzolite. Pultiisk, Poland. The Pultusk meteorite on the fresh fracture shows, according to Werther, as a light- gray rock, part very fine-grained, and part of a somewhat coarser texture. This is interspersed with numerous white and yellowish points, showing metallic lustre, also brownish-yellow spots in the groundmass. He regards the rock as composed of nickel- iron, olivine, enstatite (?), and chromite.f This meteorite was further described by Dr. G. vom Eath as composed of a fine * Sitz. Wien. Akad., 1S7Q, Ixii. (2), 855-865. f Sehriften, Kongsberg Gesell., 1S6S, ix. 35-40. THE METEORIC PERIDOTITES. LHERZOLITE. 95 granular to compact groundmass, containing nickel-iron, pyrrhotite, spherules, olivine, \vhite crystal grains, and chromite. He states that the nickel-iron occurs in three differ- ent forms : in large grains, in laminae, and in ramifying, pronged grains sprinkled through the groundmass. The surrounding groundmass is sometimes stained, through the altera- tion of the iron, to a brown color. The pyrrhotite occurs in small irregular grains and granules of a tombac-brown color, which, through a slight alteration, change to a dark steel-gray. The chromite is in very small black non-magnetic grains, and only in minute amounts.* The specimen purchased from Ward and Ho well for the Whitney Collection has an ash-^ray color and shows a chondritic structure. It contains pyrrhotite and iron. Section : composed of a light-gray chondritic mass, containing grains of iron and pvrrlmtite. The groundmass is composed of olivine, enstatite, and some diallage. The chondri are formed, in part, of grains and crystals of olivine and of enstatite, cemented by a gray, fibrous base. Like those examined by the writer in other meteorites he regards these as the product of an arrested crystallization in a rapidly cooling mass the solidification taking place before crystallization was complete. Part of the enstatite chondri do not show the usual eccentric structure, but a parallel, or sometimes a very irregular one. The arrangement of the pyrrhotite and iron about some of the chondri reminds one of the similar arrangement of the rejected or " pushed out " material about the feldspars in some andesites. The iron is in part outside of, and in part entirely surrounded by, the pyrrhotite. Figure 1, Plate III., shows a large chondrus at the base of the figure, composed of enstatitic, aggregately polarizing, fibrous material The form shows the rounded indenta- tions seen by Tschermak in the Tieschitz meteorite, and at its upper portion blends with the groundmass, although distinct from it elsewhere. Under the microscope its boun- daries appear to be those of a crystallizing mass and not those of a foreign inclusion in the groundmass. At the left of this chondrus is another radiating fibrous one, com- posed of enstatite ribs cemented by connective tissue of gray base, holding metallic iron grains. The remaining portions of the figure are composed of mixed choudri and the constituents of the rock. Figure 2, Plate III., shows the structure of a chondrus composed of olivine, enstatite, iron, base, etc., with its blending at the bottom of the figure into the groundmass. Figure 3, Plate III., shows the relations of a mass of pyrrhotite (troilite) to an inclosed mass of metallic iron, and the whole surrounded by the chondritic groundmass. New Concord, Guernsey Co., Ohio. "A crystalline granular rock containing pyrrhotite and iron, and showing yellowish- brown spots of staining arcuml the latter. Section : a light-gray crystalline mass of olivine, pyroxene and enstatite, and con- taining iron and pyrrhotite. The groundmass is stained a yellowish-brown in many places. * See further the original paper of vom Rath. Abhamllungen ans dem Gc-bietn tier \atiir\vissenj-rhaftcii, M.-itlifiiiatili, mill Mriliciu als Gralulationssclirift tier uirilrrrhriiiisfhen (icsi llsc!i:ift fur Xatur-und lleilkmitle zur feier des fnn&igjahrigen Jnliilaiims tier koiiijjlich rheiuisclicu Fricdrich-Wilhclms-Uiiiversitat. Bouu. Ain 3 August, 1SG8, pp. 135-1G1, with plate. 96 PEEIDOTITE. The enstatite, pyroxene, and olivine are in clear grains when unstained, and are much fissured and broken. Some of the enstatite shows the same structure as the chondri of other meteorites except that it wants the cementing base. That is, these grains are formed from minute grains arranged in rod-like forms, and lying side by side. The iron and pyrrhotite is in irregular masses and granules. Some colorless irregular patches were observed, giving a pale color in polarized light and resembling nephelite. Figure 1, Plate IV., shows the general structure of the groundmass, with its inclusions of iron, pyrrhotite, etc., and its ferruginous staining. This groundmass is fine-granular, with some traces of chondritic structura Mocs, Transylvania. This meteorite has been described by Koch, Tschermak, and Brezina, and the follow- ing is condensed from Tschermak's description. On the fresh fracture the rock appears as a gray and white, rough, friable mass, flecked with little brown and yellow spots, and traversed by fine black veins. The grayish-white groundmass contains small spherules of varying size, small grains of iron and pyrrhotite, and occasionally larger grains of iron. Those chondri which are granular and vary from a white to a yellowish color are com- posed of olivine, but those of a white color and of a fine rod-like or fibrous texture are composed of enstatite. Under the microscope the stone was found to contain olivine, enstatite, diallage, plagioclase, iron, pyrrhotite, rarely chromite, and a black undetermined mineral. The olivine is pale-yellowish green, and contains irregular inclusions of a fine black dust, angular black grains, and glass. The enstatit has a pale-greenish color, and contains brownish, rounded glass inclusions, spherical and lens-shaped vapor cavities, and small black spheres. The diallage contains inclusions of abundant black dust and grains, and glass, with some microlites. Part of the diallage presents the characters of diopside. The plagioclase appears in colorless rounded grains r containing many irregular, brownish, glass inclusions. In polarized light many of the feldspars show well-marked character- istic twinning. The iron is in small spheres in the groundmass and in the chondri, as well as in rounded and elongated rough grains, sometimes showing a cubic cleavage. The pyrrhotite occurs in minute grains.* Zsaddny, Temesvar Comitat, Banat. Dr. E. Cohen made a microscopic study of the Zsadiiny meteorite in 1878. Macro- scopically, the following constituents were observed: 1. A fine-crystalline, light-gray groundmass, in which appeared scattered grains with a conchoidal fracture and a vitreous lustre. These were mostly water-clear or else of a pale honey-yellow color. 2. Grains of the color of pyrrhotite, and grains or leaves of nickeliferous iron. 3. Numerous dark gray crystalline spherules, with a rough surface, and a faint resinous lustre on the surface of fracture. On the polished surface they show an elliptical form. In the thin section two classes of these spherules were seen. One is composed of small columns of an enstatite-like mineral. This contains a few small pores, and * Koch, Min. Mitth., 1883, v. 234-244; Sitz. Wieii. Akad., 1882, Ixxxv. 1, pp. 116-132; Tschermak, ibid., pp. 195-209 ; Breziua, ibid., pp. 335-343. THE METEORIC PERIDOTITES. LHEKZOLITE. 97 between the columns a cloudy substance was observed. Cohen is in doubt whether this substance is an alteration-product or has intruded. The second i.s formed from aggregations of round or angular olivine grains and a cloudy substance. The oliviue and eustatite also occur in the groundrnass. The enstatite incloses some opaque grains and colorless microlites. The olivine contains some porea which are for the most part empty, but some of them appear to hold a little fluid. Cohen thought that an accessory mineral observed was hypersthene. Pyrrhotite and nickeliferous iron were also seen. Between all these constituents lies a cloudy, very rarely feebly transparent substance which appears to be identical with that observed in the spherules. Cohen seems to adopt the mechanical theory for the origin of chondritic structure, but, following Giimbel, holds that the eccentric radiated structure of many of the spherules is owing to a secondary formation.* Cohen's cloudy substance is doubtless the gray, fibrous, base and semi-base observed by the present writer in other meteorites like the Iowa one, for instance. Esthcrvillc, Emmet Co., Iowa. The Estherville meteorite has a grayish granular groundrnass, holding irregular grains of olivine and diallage. The olivine grains are of various sizes, from minute ones to those two inches in diameter. Scattered through the mass, in irregular nodular jagged forms, occurs the iron. Some bluish-gray fragments were seen inclosed, but of an unknown nature, although they may be olivine. The groundmass is identical in appear- niicu with that of the finer-grained peridotites, and, excepting the iron, the rock is strik- ingly similar to some from North Carolina, Two or three patches composed of yellowish-green olivine, and a glassy white mineral were seen. The latter resembles feldspar or quartz, but it would probably not be found in the section, or by chemical analysis, unless especial portions were taken for examina- tion. The iron shows imperfect dodecahedral forms with striated faces. One imperfect fm in resembled a cube face modified by two pentagonal dodecahedral planes. A few small black grains were seen resembling picotite or chromite. The crust in some places shows that it was derived from the fused oliviue; hence if the fusion point of this olivine could be ascertained, it would give the minimum temperature of the surface during its passage through the air. The specimen above described, in the Harvard College Cabinet, is said to weigh twenty-eight pounds, and it affords, on account of the large extent of its frac- t lived surface, a good opportunity to study the macroscopic characters of this peridotite. This specimen, in some places, shows the remains of an internal cavernous structure, its cell-walls being lined with minute crystals. Section : a grayish groundmass, holding grains of enstatite, olivine, and diallage, with iron and pyrrhotite. The groundmass is composed of a crystalline, granular aggregate of tln'-e minerals. The olivine is in clear, rounded grains, of irregular outline. Lying in the olivine are numerous grains and irregular masses of iron, which are usually confined to certain portions of the mineral, and are wanting in some crystals. Besides the larger, easily recognizable, irregular, semi-sponge-like masses of iron surrounding, projecting into, or included in the olivine, drop-like forms are seen extending in irregular bines from Vcrh. Natur. Med. Verciu, Heidelberg, 1878, ii. (2), 154-163. 13 98 PEEIDOTITE. points on the larger iron masses through the silicate. These globules are of every size, from those whose metallic lustre and character can be readily recognized with low powers to those that remain a fine dust when magnified one-thousand times. It cannot be said that the finer dust-like portions, resembling the globules in the basaltic base, are the same as the larger globules of iron ; but the gradual transition in size between the grains of different sizes, and, with the increase in power, the increase in number of globules that can be recognized as metallic iron leads one to suspect that all these gran- ules, whatever may be their size, are of the same origin and material iron. These forms, in the minute state, are similar to some of the inclusions in the olivine of the Cumber- land pallasite, but in the latter case the iron, if occurring, would be oxidized. Some of the olivine grams show a fine cleavage adjacent to the cross fissures. The enstatite is in irregular and oval masses, with a perfect longitudinal cleavage and a cross fracture. The extinction takes place in polarized light parallel to the cleavage. The enstatite contains inclusions of olivine and of iron, the same as previously described in the olivine. The diallage has an irregular longitudinal cleavage, its forms being the same as those of the enstatite. The cleavage lines of the diallage are either cut by irregular cross- fractures, or connect by oblique fissures, so as to give an irregular network over the face, rendering it more obscure and cloudy. The extinction is oblique to the principal cleavage planes. It contains the same inclusions as the enstatite. While the olivine, enstatite, and diallage are all clear, transparent, and colorless in the thin section, yet their cleavage characters are so distinct that in general they can readily be distinguished from one another without the use of polarized light. The iron and pyrrhotite are in detached granules, droplets, irregular jagged masses, and in imperfect sponge-like forms. In some cases they form an irregular net-work in the groundmass, and in an imperfect ring surround the larger grains of olivine, enstatite, and diallage. The material for the above described sections was purchased from W. J. Knowlton of Boston. Figure 5, Plate III., represents a central crystal of diallage with the surrounding groundmass of oliviue, enstatite, diallage, iron, pyrrhotite, and the ferruginous staining. Figure 6, Plate III., shows the semi-sponge-like mass of iron and pyrrhotite with their inclosed silicates, forming a groundmass holding two porphyritic crystals of dial- lage and enstatite, showing their characteristic cleavages and inclusions, although the latter are imperfectly represented. Attention was originally called to this very interesting meteorite by Prof. S. F. Peck- ham, who stated that a preliminary examination showed that the metallic portion was an alloy of iron, nickel, and tin. " Full half the mass consists of stony matter which appears in dark-green crystalline masses embedded in a light-gray matrix. . . . Some of the crystalline masses are two inches in thickness, and exhibit distinct monoclinic cleavage. Under the microscope, in thin sections, olivine, and a triclinic feldspar appear to be imbedded in a matrix of pyroxene. ... A small piece of the metal polished and etched exhibited the Widmanstattian figures very finely."* Prof. C. U. Shepard, in the same volume (pp. 186-188), gives a further description of this meteorite. He writes: " It is marked by the unusual prevalence of chrysolite and meteoric iron, the former probably constituting two-thirds its bulk ; also by the size and distinctness of the chrysolitic individuals, together with their pretty uniform, yellowish-gray or greenish- * Am. Jour. Sci., 1879 (3), xviii. 77, 78. THE METEORIC PERIDOTITES. LHERZOLITE. 99 Mack color; and by the ramose or branching structure of the meteoric iron. Nearly line-half of the chrysolite, however, is more massive, approaching tine-granular, or com- pact. Yet in this ciuiditiou it is still highly crystalline, and difficultly frangible. This portion is of an ash-gray, flecked with specks of a dull greenish-yellow color. The lustre is feebly shining. . . . Especially is it observable that the stony portions nowhere present traces of the oolitic, or semi-porphyritic structure, so common in meteoric stones. . . . " The meteoric iron, besides being in ramose branches, is also in enveloping coatings around the chrysolite, somewhat as in the Pallas and Atacama irons. . . . The presence of schreibersite in the metal is apparent to the naked eye." The minerals that Shepard supposed that he found were chrysolite, schreibersite, chromite, troilite, a " felds- pathic mineral, presumably anorthite," and an " opal-like mineral of a yellowish-brown color, which I take to be chassignite." Later, J. Lawrence Smith made a further examination of the Estherville meteorite.* He found olivine, bronzite, nickeliferous iron, troilite, chromite, and an opalescent silicate. The last has a light, greenish-yellow color, and cleaves readily. It was regarded as formed from one atom of bronzite plus one atom of olivine. Smith further says : " I examined carefully for feldspar and schreibersite, but the absence of both limp, and alu- mina (except as a trace) clearly proved the absence of anorthite ; and the small particles of the mineral that might have been taken for schreibersite, were found on examination in all instances to be troilite." Dr. Smith's chemical analysis was made in such a manner that it is impossible from it to draw any conclusions as to the relative proportion of the elements in the mass as a whole. Later,! Smith named the " opalescent silicate" pcckhamitc, and thought from his farther analyses that it was probably composed of two atoms of bronzite to one of oli- vine In 1882 Dr: Stanislas Meunier described the microscopic characters of the Estherville peridotite, which he referred to the logronite type of meteorites one of the 43 types proposed by him in 1870. \ He found the following minerals : olivine, bronzite, peck- hamite ? pyrrohotite, schreibersite, magnetite, and nickeliferous iron. The olivine is in very large crystalline fragments, yielding in polarized light a most brilliant colored mosaic. In common light they are colorless, often cleaved and filled with crystalline inclusions. Liquid bubbles in spheroidal cavities, remarkable for their large size, were seen. In converging light the crystals show two systems of brilliant riiii^, whose axes show strong dispersion. The bronzite is in poorly formed crystals, clearly dichroic, and showing a well-marked parallel rectilinear cleavage. The pcckhamite is in large, feebly colored crystals, composed of alternations of laminae, inversely affecting polarized light. The action of acids upon them causes one to regard this mineral as composed of extremely thin interlaminated layers of bronzite and olivine. The magnetite is in perfect octahedrons. jr. Meunier concludes as follows: " In presence of these different characters of com- position and structure, it is seen that the identity is complete with the logronite already Am. Jour. Sci., 1S80 (3), xix. 459-403, 495, 490. t Am. Jonr. Sci., 1880 (3), xx. 136, 137. t Cosmos, 1870 (3), vi. 70-73, 95-98, 152-155, 186-188, 210-215. 100 PERIDOTITE. described. We must believe with respect to the Estherville form, that the primitive mass in the condition of debris, in part stony, in part metallic, accumulated in some crevice, has been subjected to metalliferous emanations, of which the product, under the form of a fine network, has soldered together the components previously disconnected. The spaces so remarkable existing sometimes between the modules of iron and their rocky matrix, are artificially reproduced in the process of metallic cementation of the dust of peridot, by a method which I have already described." * The present writer finds himself obliged to dissent from M. Meunier's views regarding the origin of this meteorite, for the following reasons : He (the writer) can nowhere in the sections find any evidence that its materials ever held any different relation than the present, and no sign of a former fragmental state is observable to him ; but he does see evidence that is convincing to him that the entire mass has been formed by cotem- poraneous crystallization, i. e., it has the same structure that a terrestrial lava of the same composition, cooling under conditions that would allow the entire mass to crystal- lize, would have. The inclusion of the iron in the silicates, indicating their later solidifi- cation, would show that the iron was not a posterior emanation. Such a formation as M. Meunier supposes could not take place without leaving a record behind of its action. It has been hoped that a complete microscopic description would have been pub- lished by Professor C. W. Hall, of the University of Minnesota (see Professor Peckham's paper before referred to, page 98) ; but thus far he has been unable to get time for the work. Professor Hall has very kindly sent me some of his sections for examination, and the additional information obtained from them is given below. The sections sent by Professor Hall are, in their general and mineralogical char- acters, so unlike those already described, that were it not for the source from which they were obtained, it would be very difficult to believe that they came from the same meteorite. They have a confused light-greenish-yellow groundmass, holding irregular masses of olivine, enstatite, and feldspar. The groundmass appears to be composed of olivine, enstatite, feldspar, pyrrhotite, and magnetite. But little native iron is to be found in the sections. The groundmass is stained a ferruginous yellow in many places, and the com- mencement of a serpentinous alteration was seen in some of the olivines. The feldspar is in irregular glassy masses, and in imperfect crystals, showing stria- tion and extinction oblique to the nicol diagonal. They contain inclusions apparently of olivine, enstatite, magnetite, bubble-bearing glass cavities, etc. The olivine and enstatite contain also glass inclusions, magnetite, etc. The enstatite in some places is diehroic along its cleavage planes, owing to its slight greenish altera- tion. These sections, having been prepared by a student, are of such thickness, and ground with so uneven a surface, that the study of them is very difficult. A few grains resem- ble quartz, but they are probably unstriated glassy feldspars. My thanks are due Pro- fessor Hall, and I regret that I cannot profit more by his kindness. These sections are so much unlike those previously described, that I trust he will have further and thinner sections made, and publish a complete description of them himself, t From the various descriptions given it is to be concluded that the Estherville perido- tite varies considerably in its mass, in different portions from those parts entirely iron, * Comptes Rendus, 1882, xciv. 1659-1661. f It is probable from their alteration that the material from which these sections were made had beeu exposed to atmospheric agencies for some time. THE METEORIC PERIDOTITES. BUCHNERITE. 101 those of a sponge-like iron mass holding silicates, those of but little iron with the sili- cates, and those that are pure or nearly pure silicates. If detached portions should be taken and analyzed chemically and microscopically, it could be claimed that this meteorite is a siderolite a pallasite a peridotite, and all be equally correct so far as the portion examined would show; but studying this meteorite as a whole, its proper place both chemically and microscopically appears to be with the peridotites. The variations in the descriptions given by the different observers who have examined this meteorite, are doubtless owing, in many cases, to the actual variation in the rock itself. It offers a striking illustration of the need of some more general method than a purely mineralogi- cal one in naming rocks. Since the preceding was written, specimens of this meteorite, containing peckhamite, have been received from Professor Peckham. The sections present for the mass of the meteorite the same composition and structure as those obtained from Professor Hall. The peckhamite presents the optical characters and cleavage of enstatite, but is filled entirely full of vapor cavities, iron, glass, brown grains, etc. To these inclusions is appar- ently owing the coloid appearance of peckhamite, and the variation in its analysis; while Meunier probably mistook plagioclase for this mineral VARIETY. Buchnerite. Ticschitz, Moravia. A microscopic study of the Tieschitz meteorite has been made by A. Makowsky and G. Tschermak. The color of the meteorite on its inner surface is ash-gray, and it has a chondritic structure. It shows many minute deep-gray, or dark-colored globules and splinters, and occasionally larger spherules of the same color ; also, little white globules and fragments, which are subordinate in amount to the former. Lying between them were seen an ash-gray earthy groundmass, and a very few yellowish particles showing metallic lustre. Certain characters of some of these spherules had never been described previously in any other meteorite. Some show a concave impression upon them, indi- cating plasticity during their formation. Some of these latter spherules also show out- side of these concavities an excrescence having a round or pointed termination. These characters not harmonizing well with Tschermak's friction theory of the formation of the globules, which will be later given in this work, (pp. 109, 110), he adopted a new theory, that while these grains are the result of volcanic eruption and explosion, their form could be derived from their plastic condition, instead of from the friction of solid particles as he had held before. The general characters of the meteorite were much the same as those of the preced- ing. Olivine, bronzite, enstatite, augite, pyrrhotite, and nickeliferous iron were the min- eral constituents observed. The olivine was found in the groundmass, and in some of the spherules. Inclusions of black angular grams, and of brownish glass with fixed bubbles, were seen. The bronzite is principally in stalk-like and fibrous forms. It contains also inclus- ions of brown glass, with immovable bubbles. The enstatite has about the same form as the bronzite, contains the same inclusions, and is white or of a pale color. It occurs in chondri and fragments. Augite was found in small amounts in globules, having the same inclusions as the olivines. 102 PE1UDOTITE. The pyrrhotite occurred in small grains, not only in inclusions in the globules and fragments, but also in the groundmass. The iron is mostly in irregular pronged particles in the groundmass. * Hungen, German//. The Hungen meteorite has been described both by Buchner and Tschermak. Tscher- mak stated that the section showed quite large particles of iron, a few small grains of magnetite, with fragments of minerals and spherules in the groundmass 4 . Some small untransparent grains without metallic lustre were thought to be chromite or picotite. The other minerals were olivine and bronzite, besides brown angular grains that were supposed to be augite. This, like nearly all the meteoric peridotites, is ehondritic. Needles and grains of a water-clear mineral, and fine grains of chromite were seen in the olivine. The enstatite contained brown needles and grains, as well as the chromic iron dust.f Grosnaja, Caucasus. The color of the interior of the Grosnaja meteorite, according to Tschermak, is a blackish-gray, sprinkled with clear to whitish-colored points. In the section the groundmass is black and opaque, while many of the inclusions were either opaque or transparent only in spots. Other inclusions were transparent, and showed mostly a spheroidal structure, although a few pieces were angular. Tschermak distinguished five different minerals : a clear-green olivine, bronzite, augite, pyrrhotite, and a carbonaceous mineral. Iron in very small amounts was also found. This meteorite showed chondritic structure, as seems to be usual with the olivine- enstatite ones.J Alfianello, Brescia, Italy. This meteorite has been microscopically studied by Baron von Foullon. It has a chondritic structure and is composed of nickeliferous iron, olivine, bronzite, an augitic mineral, pyrrhotite, and maskelynite. The fresh fracture shows a pale-grayish white finely crystalline surface sprinkled with pyrrhotite. The olivine is of a light color and generally in grains. The bronzite is somewhat of a light-yellowish to brownish-yellow color, and shows cleavage lines. The maskelynite was found as an intergrowth with the bronzite, occurring as a colorless, water-clear substance. The chondri are irregular and show about the usual structural varieties. * Denks. Wien. Akad., 1879, xxxix. (2), 187-202, 5 plates ; Sitz. "Wien. Akad., 1878, Ixxviii. (1), 440-443, 580-582 ; Verb. Nat, Verein, Briiun, 1879, xviii. 40, 41. f Mill. Mittli., 1877, pp. 313-310. % Min. Mitth., 1878 (2), i. 153-164. Sitz. Wien. Akad., 1883, Ixxxviii. (1), 433-143. THE METEORIC PERIDOTITES. 103 MISCELLANEOUS. Bavarian Meteorites. In 1878 Prof. C. W. Giimbel gave an account of his microscopic examination of five meteorites that had fallen in liavaria at different dates during the 18th and 19th centuries. Four of these are described below, and one later under The Basalts. 1. The MaucrkirscJicn Meteorite. This rock is of a light-gray color, with black spots of metallic iron, which in places show oxidation. It has a very fine-grained groundmass, which incloses blackish and yellowish grains. The stone shows the chondritic structure, and has the usual charac- ters. The groundmass contains fragments and grains of the various minerals. Giimbel holds that this meteorite contains olivine, a feldspathic and an augitic mineral, pyrrhotite, chromite, and iron. 2. The Eiclistadt Meteorite. This rock also belongs to the chondritic meteorites, and was thought by Giimbel to contain an augitic and two feldspathic minerals, as well as olivine, iron, pyrrhotite, and chromite. 3. TJie Schoncnberg Meteorite. This, like the preceding, belongs to the chondritic type, and was thought by Gtimbel to contain the following minerals: olivine, iron, pyrrhotite, chromite, schreibersite, a feldspathic, a scapolitic, and an augitic mineral 4. The Krdhenbcrg Meteorite. According to Giimbel this chondritic rock contained olivine, pyrrhotite, iron, chromite, an augitic mineral (bronzite ?) and a feldspathic mineral (Labrador ?).* It is not probable that the meteorites above described by Giimbel in reality differ much in mineralogical characters from the common forms, the determinations being here thought to be imperfect. It is therefore to be hoped that in the light of the advances made in the knowledge of the microscopic characters of minerals, a reexamination will be made to these meteorites. Charlottdown, Cabarras Co., North Carolina. This stone is described as having, on the fresh fracture, a dark, bluish-gray ground- inns*, holding porphyritically inclosed crystals and grains of a grayish-white mineral, with a tin^'c of lavender-bluet The specimen in the Harvard College Cabinet shows the usual chondritic structure, and contains considerable iron. The grayish-white minerals, with a tinge of lavender- blue, are the chondri, which are well marked in this meteorite. It possesses a striking * Sitz. Miinchcn Akail., 1S78, viii. lt-72. f C. U. Shcpard, Proc. Am. Assoc. Adv. Sci., 1850, iii. 149-152. 104 PERIDOTITK similarity to the Iowa Co. meteorite, although the chondri are somewhat smaller. Judging from the general characters of the Cabarras meteorite, it is probable that Shepard's analysis is incorrect, and it is hoped a new one will be made. Other specimens of meteoric peridotites in the Harvard College Mineral Cabinet, macroscopically examined by the writer, are : Mezo-Madaras, Transylvania. This shows a somewhat coarse chondritic structure, and contains grains of iron and pyrrhotite. Alessandria, Piedmont. This has a grayish groundmass showing an imperfect chondritic structure, and con- tains considerable iron in grains and in films running through it. Rcnazzo, Ferrara, Italy. This has a dark surface or groundmass, holding grayish-white rounded grains or chondri. Since this specimen shows no fresh fracture, but little can be said about its characters. It resembles closely, in external appearance, some of the Cordilleran andesites, possessing a dark, glassy groundmass holding rounded, glassy feldspars. This meteorite has been described before as similar to an obsidian-porphyry and possessing a compact, black, enamel-like groundmass, holding numerous light-gray spherules.* This meteorite ought to be studied microscopically, for it promises to be one of the most interesting specimens examined by that method, and will probably throw much light upon the origin of meteorites, especially if it should prove to be. as it appears, less devitrified than other meteorites microscopically examined. Hartford, Linn Co., Iowa. This has a light-gray granular groundmass showing chondritic structure, and is sprinkled with metallic particles. Ausson, Haute Garonne, France. The specimen shows a gray groundmass, and possesses a well-marked chondritic structure. Nanjemoy, Maryland. This is the same as the Ausson rock, except that its structure is of a finer character. Drake CrecJc, Simmer Co., Tennessee. This has a light-gray, fine-granular groundmass, sprinkled with iron in various forms. This stone closely resembles that from Hartford, Linn Co., Iowa. * Buclmer, Meteoriten in Sammlungen, 1863, pp. 46, 47. THE METEORIC PERIDOTITES. TUFA. 105 L'Aiglc, Onie, France. This possesses a gray groundmass, holding chondrL One of the chondri shows a concave depression, the same as those described by Tschermak as occurring in the Tieschitz meteorite. (See ante, page 101.) Weston, Connecticut. This shows the same gray groundmass as the preceding, and an excellently developed chondritic structure. Chateau Itcnard, France. This has a light-gray groundmass, sprinkled with metallic points. Hcsslc, Sweden. This has a grayish chondritic groundmass. Nobleboro\ Maine. This specimen is apparently fragmental in character, and closely resembles a trachytic or rliyolitic ash. The specific gravity, according to Webster, is 2.08, but, according to I! iimler, 3.092. It is probable that Webster's chemical analysis is not correct, the speci- men, if authentic, not bearing out any such analysis as that published by him.* This meteorite ought to be reexamined chemically, and studied microscopically. VARIETY. Tufa. Orvinio, Haltj. The structure of the Orvinio meteorite is described by Tschermak as uncommon and remarkable. The rock is composed of clear-colored fragments, surrounded by a compact, dark, cementing mass. The fragments are yellowish-gray, and contain spherules and particles of iron and pyrrhotite. The cementing material is blackish, compact, and splintry, holding nearly uniformly -distributed particles; and near its contact with the fragments shows an evident fluidal structure. This makes it in the highest degree probable that the cement- ing material was once in a plastic condition and in motion. The fragments are darker, harder, and more brittle at the junction with the inclosing mass than they are in the middle. From this it would seem that the matrix had been at a very high temperature when plastic. The fragments and matrix both have almost the same composition, density, and mineral characters. This meteorite resembles a volcanic rock in which a fine matrix holds fragments of rock of the same character. The structure is the same as it is when a younger compact lava breaks through an older and more crystalline one. The fragments have the usual chondritic structure. They contain, besides iron and pyrrhotite, oliviue, bronzite (enstatite), and possibly some feldspar. For the further Bost. Jour. Phil., 1824, i. 3SG-389; Buchner, Mcteoriteu in Saminlungeu, 1863, p. 46. 14 10G THE METEOEITES. THEIE ORIGIN AND CHARACTER. description and figures the reader is referred to the original paper. * If Tscherrnak is correct this meteorite must have come from a body either partly solid and partly liquid, or one in which cooler fragments fell into the liquid mass. Chantonnay, Vendee, France. This is described by Tschermak as composed of olivine, bronzite, a finely-fibrous translucent mineral, nickeliferous iron, and pyrrhotite. Its structure is similar to the Orvinio meteorite ; that is, is composed of chondritic fragments cemented together by a black, glassy and semi-glassy material, f SECTION' III. The Meteorites. Their Origin and Character. IT is thought most convenient to ente'r upon these questions here in con- nection with the Largest class of authenticated meteorites. And in doing this the views of those persons who have studied them microscopically will be especially referred to. Professor N. S. Maskelyne taught, in 1863, regarding the chondritic meteo- rites : " that there have been stages in the progress of the slag-like mass from the first origin of the spherule in perhaps a seething lake of mixed and molten metals on which a rare oxygenous atmosphere was acting and fermenting out as it were the more oxidizable ele- ments to the final state of compact continuity in which the spherules are found agglu- tinated toether or imbedded in a mama of mineral." \ The previous year he had said : " The spherules which characterize this structure are often composed of a single crys- talline and homogeneous mineral, with a radiating structure ; often they are breccias made up of several crystals of the same or of different minerals united by a granular network of mineral. These spherules are often surrounded by a shell of meteoric pyrites or iron, and are set in a mixed mass, often highly porphyritic, composed of similar ingre- dients with the spherules. The solidification of this ground-mass marks, probably, a second stage in the history, the former indicating the very gradual separation by cooling of some of the ingredients of the aerolite, and the latter the result of the further gradual cooling of the residuary mass. There is no glass or uncrystallized matter apparent in any aerolite yet examined." Professor Maskelyne's views were set forth again in 1875, but with great caution and indefmiteness. The following extract gives the chief additional point bearing on the chondritic structure : " We may, perhaps, go so far as to suppose that if groups of the individual particular units of a meteor cloud once should approach each other to a distance small enough to * Sitz. Wien. Akad., 1874, Ixx. (1), 459-465. f Site. Wien. Akad., 1874, Ixx. (1), 465-472. { Phil. Mag., 1863 (4), xxv. 440. Proc. Brit. Assoc., 1S62, xxxii. (scot.) 188-191. SOllBY'S VIEWS. 107 <_;ive tlu-ir mutual gravitation a sensible influence, they might gradually collect into masses, and acquire a cohesion more or less compact according to the conditions imposed on such masses during their subsequent history. . . . We may, indeed, assert that the meteorites we know have, probably all of them, been originally formed under conditions from which the presence of water, or of free oxygen, to the amount requisite to oxidize entirely the elements present were excluded ; for this is proved by the nature of the minerals constituting the meteorites, and by the way hi which the metallic iron is dis- tributed through them. " In 1864, Mr. H. C. Sorby announced the presence of gl;n tides lead me to conclude that it was broken up into detached globules whilst still melted." f The same year Mr. Sorby remarked that the earliest condition of meteo- rites was that of igneous fusion, but he thought that the Pallas iron afforded "physical evidence of having been formed where the force of gravitation was much smaller than on. our globe, either near the surface of a very small planetary body, or towards the centre of a larger, which has since been broken into fragments." f In 1865, Mr. Sorby developed his views still further, stating : " The character of the constituent particles of meteorites and their general microscopi- cal structure differ so much from what is seen in terrestrial volcanic rocks, that it appears to me extremely improbable that they were ever portions of the moon, or of a planet, which differed from a large meteorite in having been the seat of a more or less modified volcanic action. A most careful study of their microscopical structure leads me to conclude that their constituents were originally at such a high temperature that they were in a state of vapour, like that in which many now occur in the atmosphere of the sun. . . . On cooling, this vapour condensed into a sort of cometary cloud, formed of small crystals and minute drops of melted stony matter, which afterwards became more or less dcvitritied and crystalline. This cloud was in a state of great commotion, and the parti- cles moving with great velocity were often broken by collision. After collecting together to form larger masses, heat, generated by mutual impact, or that existing in other parts * Nature, 1S7.J, xii. 485-437, 504-507, 520-523. f Pn>c. liny, s*., 18G3-64, xiii. 333, 334; Phil. Mag., 1804 (4),xxviii. 157-159; Report Brit. Assoc., 1865, xxxv. 13"9, 140. J (imi. MM-., 1864 (1), i. 240, 241 ; Report Brit. Assoc., 18C4, xxxiv. (sect.) 70. 108 THE METEORITES. THEIR ORIGIN AND CHARACTER. of space through which they moved, gave rise to a variable amount of metamorphism. In some few cases, when the whole mass was fused, all evidence of a previous history has been obliterated ; and on solidification a structure has been produced quite similar to that of terrestrial volcanic rocks. Such metamorphosed or fused masses were sometimes more or less completely broken up by violent collision, and the fragments again collected together and solidified. Whilst these changes were taking place, various metallic com- pounds of iron were so introduced as to indicate that they still existed in free space in the shape of vapour, and condensed amongst the previously formed particles of the meteorites. At all events, the relative amount of the metallic constituents appears to have increased with the lapse of time, and they often crystallized under conditions differing entirely from those which occurred when mixed metallic and stony materials were metamorphosed, or solidified from a state of igneous fusion in such small masses that the force of gravita- tion was too weak to separate the constituents, although they differ so much in specific gravity. ... I therefore conclude provisionally that meteorites are records of the exist- ence in planetary space of physical conditions more or less similar to those now confined to the immediate neighborhood of the sun, at a period indefinitely more remote than that of the occurrence of any of the facts revealed to us by the Study of Geology at a period which might, in fact, be called prc-tcrrcstrial.' '* These views of Mr. Sorbj were again given to the public, with additional matter, in 1877. He then stated that ".it is very probable, if not absolutely certain, that the crystalline minerals were chiefly formed by an igneous process, like those in lava, and analogous volcanic rocks. . . . Some [of the spherules] are almost spherical drops of true glass in the midst of which crystals have been formed, sometimes scattered promiscuously, and sometimes deposited on the external surface, radiating inwardly ; they are, in fact, partially devitrified glob- ules of glass, exactly similar to some artificial blow-pipe beads. ... I ... argue that some at least of the constituent particles of meteorites were originally detached glassy globules, like drops of fiery rain. . , . We cannot help wondering whether, after all, meteorites may not be portions of the sun recently detached from it by the violent dis- turbances which .do most certainly now occur, or were carried off from it at some earlier period, when these disturbances were more intense." f David Forbes stated that meteoritic stones are seen under the microscope " to be an aggregation of fragmentary matter resembling a volcanic ash or breccia, in which, whilst some of the particles have been in a molten state (the presence of both glass and air cavities in them indicating that they were in the molten state when gases or vapours were being given off), others show no signs of fusion ; so that the structure of meteorites confirms the views that they have been formed out of the debris of some pre- viously existing larger mass, or even out of the ruins of some planetary body." $ Dr. Stanislas Meunier has done much work in the study of meteorites, published a large number of papers, and holds some decidedly original views regarding their origin. He maintains that all have a common origin, and * Geol. Mag., 1865 (1) ii. 447, 448. f Nature, 1S76-77, xv. 495-498. % Geol. Mag., 1S72 (1), ix. 222-235. THEORIES OF MEUNIER AND TSCHERMAK. 109 possess types corresponding to rocks and structures of terrestrial origin, i. e. to lavas, d unite, Iherzolite, serpentine, breccias, pumice, metallic veins, metamorphic rocks, etc. David Forbes thus concisely gives the views of the former : " Meunier, who has of late written more copiously than concisely on the subject of meteorites, whilst believing them to be fragments of broken-up planets, regards these bodies as but the last stage in the evolution of planetary bodies, and suggests that the moon is rapidly coming to this stage from the irregularities and incipient fissures visible on its siirt'nee, its dissolution not having taken place before, owing to its greater magni- tude; arguing still further, that once broken up into fragments, 'these would arrange themselves concentrically according to their densities, those which before formed the cen- tral part of the planet, which he regards as most heavy and metallic, on the outside ; and the others, according to their weight, in the interior. This arrangement he considers a< , ounts for siderites or meteoric irons having first fallen in the earliest ages of the world, then the siderolites [pallasites], and afterwards the stone or aerolites proper; and owing to the meteorites of some recent falls, particularly that of Hessle in Sweden, hav- ing contained considerable carbon, he predicts the fall of a totally different class of meteorites in future. These hypotheses seem, however, to be but mere assumptions inca- pable of proof, for although only some very few instances of siderites [siderolites] hav- ing fallen in historic times are recorded, as compared to the much larger number of aerolites ; still there is no proof that the proportion was different in prehistoric times, especially as it is well known that the latter would be infinitely more likely to escape observation than the former." * Prof. Gustav Tschermak, in 1875, taught that meteorites were the result of the disruption of cosmical bodies by explosive agencies. He stated that " the constitution of many of the meteorites shows that they are the result of a grad- ual tranquil crystallization ; while others, on the contrary, are composed of fragments, and are the product of disintegrating forces. The majority are made up of minute flakes and splinters and of rounded granules." Following Haidinger, he regarded the chondritic meteorites as tufas, and states that the spherules have the following characters : " 1. They are imbedded in a matrix consisting of fine or coarse splinter-like par- ticles. " 2. They are invariably larger than these particles. " 3. They are always distinct individuals, never merging into each other or joined together. " 4. They are quite spherular when composed of a tough mineral, and in other cases merely rounded in form. " 5. They consist sometimes of one mineral, sometimes of several minerals, but always of the same material as the matrix. " 6. The structure of the interior of a spherule is in no way related to its external form. They are either fragments of a crystal, or have fibrous structure (the fibres * Geol. Mag., 1872 (1), ix. 234. 110 THE METEORITES. THEIR ORIGIN AND CHARACTER. taking an oblique direction towards the surface), or have irregularly barred structure, or are granular. " These chondra bear no indications of having obtained their spherular form by crys- tallization. . . . They resemble rather the spherules which are frequently met with in our volcanic tuffs. ... As regards the last mentioned chondra, we know them to be the result of volcanic trituration, and to owe their form to a prolonged explosive activity in a volcanic ' throat,' where the older rocks have been broken up, and the tougher particles have been rounded by continued attrition. The characters of the meteoric chondra indi- cate throughout a similar mode of formation. ... It is certain, in short, that the spher- ules are the result of trituration. " The [meteoric tuffs] are peculiarly characterized as containing no trace of a slag-like or vitreous rock, nor enclosing distinct crystals in the matrix; in short they exhibit nothing which their formation from lava would lead us to look for. All that is to be seen in them is the triturated product of a crystalline rock. Some of the tufaceous meteorites bear evidence of a later modification wrought by heat. . . . Others, again, exhibit phenomena which can only be explained on the theory of their having under- gone a chemical change subsequent to their formation. . . . Still, with the many proofs which we possess of the action of heat, we have not yet met with a meteorite which resembles a volcanic slag or a lava. Although the meteorites are comparable to vol- canic tuffs and breccias, this comparison cannot be extended beyond a certain point. The volcanic activity, of which the meteorites furnish evidence, consisted in the disinte- gration of solid rock, in the modification, by heat and otherwise, of already solidified masses. ... It is, then, by explosive activity, and that alone, that the breccias and tuffs which we find in meteorites have been formed. . . . The volcanic activity of which those mysterious masses of stone and metal are evidence, may be compared to the violent movements on the solar surface, the more feeble action of our terrestrial volcanoes, or the stupendous eruptive phenomena of which the lunar craters tell the history. . . . Vol- canic activity is a cosmical phenomenon in the sense that all star-masses at a stage of their development exhibit a phase of volcanic activity." j The objections to the theoretical views of Tschermak, Sorby, Forbes, and Maskelyne, can be briefly stated as follows : The chondritic structure appears to be limited to meteorites of a peculiar chemical and mineralogical character, while all, even of this special kind, do not possess such structure. Hence', if it was purely mechanical, one can hardly see how this structure could be so localized, not even being universal for this special class. Again, if the spherules are the broken-up, and rounded fragments of prior existing rock, they should have the composition of that rock as a whole, instead of generally being composed either of olivine and base, or of enstatite and base. Also, they ought to show in their interior the structure of the rock from which they were derived ; while distinct lines of demarkation, and a want of continuity, ought to exist between * Phil. Mag., 1876 (3), i. 497-507 ; Sitz. Wien. Akad., 1875, Ixxi. OG1-G73. TIIK CHONDKIT1C STRUCTURE. Ill each spherule and the adjacent matrix, as is the case with terrestrial rocks so organized. Such a relation does not appear to exist, except rarely in meteorites, but the chondri usually pass into the adjacent matrix the same a< the secretions formed by a cooled lava do into the surrounding magma. So, too, we find different materials mixed in terrestrial tufas ; and since dif- ferent kinds of rock fall in meteorites, these supposed meteoric tufas, if of mechanical origin, ought to contain all these different forms, instead of only the same material as the groundrnass. As stated previously, it seems to me, from microscopic study of these structures, that they do not show any evidence of fragmented origin, but they show rather that they have been produced by rapid and arrested crys- tallization in a molten mass ; the result being in part due to the forms which the divine and enstatite tend to assume on crystallization. If time enough had been given, an entire crystallization of the material would have taken place, as in the Estherville peridotite, and in the common ter- restrial peridotites. Of the latter, the crystallization is either complete, or else the original structure has been obliterated by alteration. If we could find rapidly cooled, unaltered terrestrial peridotic rocks, I should expect to find in them the chondritic structure, the same as the Esther- ville meteorite possesses the structure of an unaltered terrestrial peridotite, and the meteoric pallasites possess that of the terrestrial ones. A similar method of crystallization, with the production of a similar struc- ture, has been observed by me in the crystallization of watery vapor on the windows of horse-cars during extremely cold weather. When the window is Tintouched the crystallization is after the usual manner, familiar to all as occurring in our houses ; but when the car-window has had this first deposit removed, ;\s is frequently done by passengers, for the purpose of looking out, the abundant vapor of the crowded car is rapidly deposited on this cold surface, and in such abundance as to give rise to similar elliptical and spheru- litic figures, which in form and appearance resemble the chondritic forms the more closely the more they interfere with the development of one another. They also possess the eccentric-fan and ribbed structure so commonly seen in the enstatite chondri the radiation starting from one side. Again, on interfering with one another, they tend to take a rounded, instead of an angular or irregular form. That rounded, drop-like masses should be inclosed in meteorites is natu- rally to be expected, in case they came from the sun or any similar body, for 112 THE METEORITES. THEIR ORIGIN AND CHARACTER. material is continually being thrown up from their surfaces and falling back again ; and it is to be expected that some of these drops would be inclosed and thrown up in other masses before they had been entirely liquefied, although they were probably viscous. So far as meteorites have been examined by me, they do not appear to be fragmental in the sense of consolidated cold masses joined together. It is possible that they may be composed in part at least, of molten globules - originally united in a pasty condition ; but the uniformity of composition of each spherule is a remarkable circumstance, if they are formed from drops. One would suppose that each chondrus would possess all the elements of the meteorite as a whole. So far as can be learned from the structure of most meteorites, it appears to the writer that they must have come from a liquid mass, and that in the majority of cases the length of time in which they passed from the liquid to the solid condition was not great. The silicates held in the interstices of metallic masses, like the pallasites, would have time to crystallize through the effect of the heat of the surrounding iron, and the chondritic structure would not be developed in this class as a rule, if at all ; while Professor Ball's* claim that meteorites must have been torn from a solid rock does not seem to be borne out by -the structure of the meteorites themselves. Starting with the hypothesis that all cosmical matter was originally in a gaseous state, and that this gas, through condensation or otherwise, was intensely hot, the writer believes that the meteoric material, reaching the earth, was thrown from some one or more of these condensing bodies, formed from this cosmi- cal matter during its liquid or partially solid state. He holds that of these bodies, the most probable one serving as the source of meteorites is the sun, as suggested by Sorby they either being thrown from it now, or in past time, through eruptive agencies, whose action can now be seen upon its sur- face. It is of course possible that any of the celestial bodies, when in the incandescent condition, while eruptive forces were sufficiently active, might be the originator of meteorites ; but before any meteorites are attributed to them, it is necessary that it should be shown that their probable constitu- tion corresponds to that of the meteorites in question. The number of elements common both to the sun and meteorites lends some support to their relation as advocated here. These elements are iron, titanium, calcium, manganese, nickel, cobalt, chromium, sodium, magnesium, * Science for All, iv. 31. THE ERUPTIVE ENERGY OF THE SUN. 113 copper, hydrogen, vanadium, strontium, aluminum, sulphur (?), oxygen, lithium, tin, and carbon. The question whether it would be possible for meteorites to be derived from the sun by their being thrown off from it by eruptive agencies, is a problem for physicists ; if it can be shown that the sun's constitution is such as to render it not improbable that meteorites could have this origin. The immense velocities of the eruptive prominences from 100 to 200 miles per second, or, according to Proctor, 500 miles indicates, with their great height of sometimes from 150,000 to 350,000 miles, a violence of eruption tending to hurl solid materials far away from the sun into space. The ele- ments seen in the spectrum of these prominences, iron, sodium, magnesium, titanium, calcium, chromium, manganese, and probably sulphur, are with one exception, common ingredients in meteorites.* If the above-mentioned velocity may, on investigation, be deemed suffi- cient to project matter into space, the prevailing view of astronomers that the sun as a whole is gaseous, and neither liquid nor solid, would certainly be opposed to the solar origin of meteorites. As before stated, their con- stitution would, so far as we are acquainted with the action of gaseous substances, demand that the meteorites should be derived from a hot liquid. The body from which they came might be for the most part solid, or gaseous, or both, but that the portion from which they came should be liquid seems a necessity. The liquid condition of the sun is also the best explanation of the eruptive phenomena now observed upon it.f Should it be shown that meteorites might come from the sun, its eruptive energy being sufficient, it would be rendered probable then that meteorites might have been thrown from the sun when larger, as well as from the planets and their satellites during their condensation if the nebular hypo- thesis is accepted. It would certainly seem that the present view of the partial or entire meteoric constitution of the corona, the zodiacal light, the G>'>/i',ixrlin,i, of Saturn'sx rings, and of comets, bears directly on this question. If our sun may do this, is it not consistent to suppose that other suns may do the same, and thus account for the comets, their varied orbits, as well as for the supposed diverse constitution of the August and November meteors. The theory that meteorites come from the sun is by no means a new one, * Young, The Sun, 1881, pp. 202, 207-212. f Youug, /. r., p. 211. 15 114 THE METEORITES. THEIR ORIGIN AND CHARACTER. being as old as the days of Diogenes Laertius, and in recent times has been advocated by Hackley,* Wilcocks,t Williams, $ Sorby, and others. If, in the process of condensation of the sun from a gaseous to a liquid state, the metallic portion liquefied before the silicates, would it riot in some measure account for the metallic meteorites being so common in the past and rare at the present time, and for the peridotic ones being the common type now ? On account of their specific gravity, meteorites, as a rule, could not be derived from the moon ; unless it should be held that its interior is now much hotter than the earth's interior, and its density made less through that means. This is an improbable supposition on account of its small size, compared with that of the earth, which would lead to its more rapid cooling. Since the specific gravity of the moon, as a whole, is about that of the more common meteorites, and if the law of the increase of density from the sur- face to the centre is the same as that observed upon the earth, it follows that the moon's surface formations must have far less density as a whole than those belonging to the earth. The law of eruption as observed upon the earth is, that the lighter eruptive material as a whole is most abundant, while the rocks approaching the mean density of the earth are compara- tively rare, so much so that their presence is generally denied. This law ought also to hold good on the moon, and eruptive material from it, forming meteorites, ought to have less specific gravity as a whole than our granites. The astronomical reasons have usually been regarded as sufficient to show that meteorites could not come from the moon, and that theory is not now especially urged by any one. Such a view as advocated by Messrs. Ball and Rodwell, that meteorites were thrown from the earth in past times, is negatived by their general composition, which, as a rule, is different from the exterior portions of the earth. If they were originally terrestrial, these meteorites ought to more commonly possess the characters of basalts, andesites, trachytes, etc. Whether the view that meteorites came from the sun demands too great a loss to his mass, since accurate records have been kept, is a problem for the physical astronomer. Since it is possible that careful examinations of meteorites by chemical and spectral methods will throw light on the constitution of the celestial * Proc. Am. Assoc. Adv. Sci., 1360, xiv. 4-6. f Proc. Am. Phil. Soc., 186 K ix. 381-387. J The Fuel of the Sun, London, 1870, pp. 131-142. Science for All, iv. 32; Nature, 1879, xix. 493-495. CONTEMPORANEOUS CRYSTALLIZATION OF IRON AND SILICATES. 115 bodies especially concerning the strange lines in the sun's spectrum it would appear that meteorites ought to be studied more critically than ever for the rarer elements, as well as for some at present unknown. Careful examinations ought also to be made on microscopic sections of recently fallen meteorites, in order to ascertain if any changes have taken place in the rock since it was first formed, but before it reached this earth, since all changes now seen in them are referred to the action of our atmos- phere after the fall of the meteorite. It is not to be expected that in any way can any clue be obtained as to how recently or how long ago the meteorite left its parent mass, since no alteration in its substance can be expected to have taken place in inter-solar space. Mr. H. C. Sorby's view* that it is impossible for minerals of so diverse specific gravity as iron and olivine to crystallize together in the pallasites and other metallic meteorites on the surface of the earth or any large body, but that they came from the metallic centre of small bodies, or else formed small planets by themselves, does not seem to be well founded. The same method of reasoning would prove that magnetite could not be formed with leucite, or feldspar, or augite in any lava-flow on the earth's surface ; yet they are minerals of common occurrence together in lavas. Hence it is claimed liere that the crystallization of silicates with metallic iron might, so far as gravity is concerned, take place on the surface of the earth as it has been proved to have done in Greenland. So too, if such a structure and arrangement of iron and olivine could not take place on the surface of a body like the earth, then the rocks of Cumberland, Rhode Island, and of Taberg, Sweden, ought not to exist since they have this structure and are at the surface of the earth. The difference between the magnetite and olivine is not so great as that between the native iron and olivine, but yet it is suffi- cient to cause a separation, if Sorby's view is correct. Helmholtz's theory that the earth is built out of meteorites is negatived by the following facts : the geological formations in and of themselves are not composed of detached fragments like meteorites ; meteorites, so far as known, are not found in the geological formations ; and the chemical com- position of the latter is different from that of the meteorites. His view seems to be a pure theory without any regard being paid to the actual known structure and composition of the earth and meteorites. As well Quart. Jour. Sci., 1864, i. 747. 116 THE METEORITES. THEIR ORIGIN AND CHARACTER. might the physicist explain the dispersion of boulders in the northern drift,* or the origin of the large nuggets in the gold placers by supposing that they were meteorites, as to explain the earth's structure by the meteoric theory. The further supposition that the earth has been formed from meteoric matter that became entirely fused from the impact of the falling masses is one that makes an assumption and then deprives us of every means of dis- proving or proving it. Everything relating to the state of the earth prior to its fluid condition is of course a matter of conjecture, and theories relating to it are beyond scientific discussion, as belonging to the unknown and unknowable. The origin of meteorites, as shown by their structure, yields but little assistance to the theory of the introduction of life upon this planet through their agency; since the conditions under which they were formed, and those, so far as can be ascertained, to which they have been since subjected are not compatible with life as understood upon this globe. t In other words it may be said that meteorites show in their structure that they have been formed from molten liquid material, while their chemical composition is such as to show that they could not have been exposed to air and water upon any globe in conditions compatible with life as we under- stand it. If their structure points to an igneous origin, and their composition shows that they could not have been exposed to conditions such as earth-life demands, then Sir William Thomson was not right in claiming that it was scientific to suppose that life was brought to this earth by meteorites. It certainly only pushes the question of life a little farther off; it begs the question but does not solve it, even could it have been shown that life might have been thus brought here. Zollner was indeed right in opposing this theory and regarding it as unscientific. Assuredly, the germs inclosed in crevices would be destroyed by the cold of space, as much as the exterior ones would be by the heat generated by the passage of the meteorite through the air. It is not intended to state that water or air could not be present on the body from which meteorites come, but that the meteorites could not have been exposed any length of time to such agencies, or their constitution would have been changed. * Since the above was written such an explanation has been published, entitled : " Ragnarok the Age of Fire and Gravel," by Ignatius Donnelly. f W. Thomson, Proc. British Assoc., 1871, pp. civ., cv. ; 1877 (Sect.), p. 43 ; A. Thomson, ibid., 1877, p. 75 ; Ilelmholtz, Popular Scientific Lectures (Sec. Ser.), 1881, pp. 193, 196, 197; Nature, 1875, xi. 212; J. C. F. Zollner, "Ueber die Natur der Cometen, Leipzig," 1872, p. 21; Walter Flight, Pop. Sci. Rev., 1877, xvi. 390-401 ; David Forbes, Geol. Mag., 1872 (1), ix. 234, 235. THE SOURCE OF VEIN MATERIALS. 117 Again .since mineral veins appear to have been formed on the earth by the action of percolating waters, none of the meteorites can be of such vein formation, as has been claimed by M. Meunier, since they show by their com- position that they have not been exposed to or formed in the presence of water; and so far as the present writer is concerned, he sees nothing in their structure supporting such a theory, even if, as Meunier seems to think, these veins were formed by sublimation. The finding of many of the metals, in larger or smaller amounts, in meteorites points to a relation between them and terrestrial eruptive rocks. The association of metallic veins with eruptive or metamorphosed rocks, coupled with other characters, indicates that our metals, as concentrated in veins, have generally been derived by aqueous and chemical agencies from eruptive rocks and their debris. This deposition may be direct or indirect, but primarily the starting point is believed to have been the original molten material of the earth.* The more common association of metalliferous veins with basic rather than acidic rocks points towards the deeper-seated origin of the former, as has been claimed by many.f The occurrence of copper in so many of the meteoric forms has, it seems to the writer, an important bearing on the question of the origin of the native copper of Lake Superior. He holds that it was derived from the associated basaltic rocks as he has set forth in another paper. $ If copper is an almost constant associate of meteorites, ought it not to naturally be associated with eruptive rocks which are held to be part of the original materials of which the solar system is composed ? The basic rocks are naturally, then, the ones with which the copper should be associ- ated, and it is with basaltic rocks diabases and melaphyrs that it is commonly found, as, for instance, on Lake Superior, Bay of Fundy, and in Newfoundland. The metallic iron in the basalt of Greenland, the native iron found in b;isilts by Dr. Andrews, that found in gabbros from New Hampshire, by Dr. George W. Hawes, and in gabbros from the west of Scotland, by Mr. J. Y. Buchanan, all serve to connect the meteorites with the terrestrial rocks. * Whitney, Aurif. Gravels, pp. 310, Oil. J- Whitney, Earthquakes, Volcanoes and Moimtuiu Building, p. 85. j Bull. Mus. Coinp. Zool., 1SSO. vii. 130. Baporl I'.rii. isMO., 1852, xxii. (Sect.) 34, 35; Geikie's Text Book of Geology, 1882, p. 61; Geol. Nrw Hampshire, Ib79, iii. part i, p. ii. 118 PERIDOT1TE. In the same way the presence of nickel, chromium, tin, copper, and cobalt in the group of terrestrial olivine minerals, serves to connect the earth and meteoric bodies ; as also does the presence of nickel in the terrestrial pyrrhotite and magnetite. SECTION IV. The Terrestrial Peridolites. VARIETY. Dunite. Franklin, North Carolina. 5134. An oil-green, crystalline-granular rock, weathering from a yellowish-green to a reddish-brown. Composed of a granular mass of olivine, holding irregular grains and crystals of chromite and long needles of tremolite. It contains some talc and dark-green chlorite. Section : a clear, pale-yellowish, fissured mass, composed of olivine, with some talc, chromite, and tremolite. The olivine is in clear transparent grains, tinged slightly yellow along the fissures. It contains some chromite and glass inclusions, the two often being associated. The talc is in clear irregular plates, showing a longitudinal cleavage. The polarization is generally simple, but sometimes aggregate. An earthy, white substance was observed in some cases lying between the laminae. The chromite is generally in octahedral crystals, although a few minute grains of irreg- ular form were seen. The chromite was opaque in every instance. A few minute rounded grains were observed, that may possibly be picotite. The section, to my mind, presents the characters of a granular rock, resulting from a cooling igneous magma an eruptive rock. The olivine is in grains which are separated only by fine cracks, every irregularity in one being matched by corresponding irregular- ities in its neighbors. If these grains were olivine sands aggregated by wind or water, such uniformity would not exist. The grains would be irregularly massed together, with interstitial portions filled with binding material. The cracks which separate the different individual grains are the same as those which separate different portions of the same grain. The absence of any signs of wearing to the grains, and their matching one another as they would in this substance when completely crystallized, point towards an eruptive origin for the rock. In addition, long, lenticular, much broken grains are seen, whose parts show in polarized light that they belong to the same individual. They are arranged at every angle with one another ; but if these grains had been deposited as a shore sand, it is difficult to see how they could have retained their sharp thin cutting edges. Again, these grains and the general structure of the rock are like those observed in the Estherville meteorite, which I think no one would be inclined to regard as a beach deposit. The granular structure appears to me to be due to the crystallization of a mineral inclined to take such a rounded form as olivine usually has. The same structure and arrangement of the grains from a cooling eruptive rock had been previously seen by the writer in quartz in some granitoid rocks from Lake Superior, part of which are known to be in dikes, while the others are probably also eruptive.* Many of the larger olivine grains show a faint banded polarization, the bauds being nearly parallel with a crystallographic axis. The structure of this section is shown in Plate IV. figure 2 ; the darker bauds indicating the fissures in the grains. * Bull. Mus. Comp. Zobl., 18SO, vii. 53-55. THE TERREST1UAL PEIUDOTITES. DUNITE. 119 W< lister, North Carolina. 5135. A oiyatalline-gnQttlar rock, of a yellowish-brown color on the fresh fracture. Lustre resinous and greasy, fracture uueven-conchoidal. Weathered to a granular pale- yrllow mass, on tlie exterior portions. Contains grains and crystals of picotite. Section : of a pale-yellow color ; composed of olivine, enstatite, diallage, picotite, and .serpentine. The oliviue forms the chief portion of the rock, and is in irregular fissured grains. It is clear-transparent, and holds grains of picotite, some of which are in minute lenticular forms. The picotite is very abundant, but mostly in minute microscopic grains of a coffee-brown color. The macroscopic picotites are opaque, except in the thin- nest portions. The enstatite and diallage are in small, transparent, irregular masses, lying between the olivine grains. Both are traversed by longitudinal fissures, but in general the enstatite i -It -avage is better marked and more finely fibrous than that of the diallage. The latter mineral was observed sometimes to have the irregular, approximately right-angled cleav- age of augite. Although the enstatite could sometimes be separated from the diallage by its cleavage, in general the distinction was made solely by optical methods. , The serpentine is mainly of a pale-yellowish color, although in some places a darker or brownish color was observed. It follows the fissures, making a network, envelop- ing the fragments of olivine, enstatite, and diallage. Many of the oliviue grains now separated by serpentine are seen by their optical characters to be parts of the same original crystallographic mass. The serpentine is plainly a secondary product, formed from the alteration of part of the original minerals, comprising this peridotite. In some parts of the section in which the mineral fragments were small, the minerals have been changed entirely to serpentine, forming ganglion-like masses in this plexus of serpentine. The serpentine shows the common fibrous polarization, the fibres standing perpendicular to the svalls of the channel. Plate IV., figure 3, shows well the yellowish and greenish serpentine alteration along the fissures, and surrounding the clear olivine grains. The brown spots are picotite grains. Dr. F. A. Genth, in 1862, made an examination of some Webster (Jackson Co., X. C.) peridotite, and stated that they gave " evidence that chrysolite is probably the mineral from which talc slate and many of the serpentines have been formed." * Dr. Alexis A. Julien regards the North Carolina peridotite as formed by consolidated olivine sand a detrital deposit derived from the wearing down of older eruptive rocks. He describes the rock as occurring in long lenticular masses, that show a laminated struc- ture ; giving his reasons why he regards this lamination as due to the sorting of sediments deposited in water. His reasons for holding that the dunite is a sedimentary rock are good so far as they go, but they do not appear to be conclusive ; since the same condition of things could readily exist in an eruptive rock. The rock, when altered near the surface of disintegration, is, according to Julien, bound together by a network of quartz or actino- lite fibres. The alterations in the rock-mass, as traced out by Dr. Julien, are very interesting. Briefly, they are as follows: 1. Chalcedonic; 2. Hornblendic; 3. Talcose ; 4. Ophiolitic; 5. Dioritic. In the first, the silicates are decomposed, the silica forming chalcedony or chert, while the bases remain as soft ochreous grains, or are entirely removed. * Am. Jour. Sci., 1862 (2), xxxiii. 199-203. 120 PERIDOTITE. In the second case, the alteration consists in the formation of a few crystals, and in every gradation from that to a state in which the dunite has been transformed into a more or less schistose rock, largely composed of hornblende, and actinolite or tremolite. A few "rains of olivine usually remain unchanged even in these extreme alterations. The third change is brought about either by the direct alteration of the olivine, or by the conversion of the secondary actinolite itself into talc. Through this alteration talcose rocks are formed, like talc-schists ; as well as amphibolitic or olivine ones bearing talc. The fourth alteration has been described by me in the preceding account of the Web- ster peridotite, and hence I will not here quote from Dr. Julien, farther than to say that according to him talc is frequently associated with the serpentine, thus forming a talcose serpentine. The fifth and last alteration is " confined to a single locality, and consists of an inter- nal conversion of the olivine into amphibole a bright grass-green variety which Dr. Genth has identified as smaragdite or kokscharoffite and albite, sometimes with abun- dantly disseminated particles of ruby red corundum, producing a peculiar variety of diorite or gabbro. Again, this very rock has been subsequently attacked by a secondary process of alteration, the albite grains being enveloped by an alteration-crust of margarite, and the condition of hornblende modified. The result of this action is a coarse margaritic gabbro." Dr. Julien believes that many of the amphibole and talc-bearing schists and serpen- tines along the Appalachian belt are the equivalents of the North Carolina dunite. The North Carolina peridotites have been described in previous papers by Genth, Jenks, Kerr, C. D. Smith, Shepard, J. L. Smith, Raymond, and others.* In most of the above papers, corundum is especially treated of, since it has been largely found associated with the peridotites of the Southern States. This mineral Genth regards as original, but Julien as a secondary product of alteration. Various opinions have been advanced concerning the North Carolina peridotite that it is of chemical, sedimentary, and eruptive origin. Messrs. Kerr and C. D. Smith who have, except Julien, studied the rock most in the field, regard it as eruptive, but the published evidence given by them is, like Julien's, not conclusive. The reasons that the present writer has for believing this rock to be of eruptive origin have already been given. It hardly seems possible that the olivine could have been deposited as a loose sand, exposed to water and air, consoli- dated, and remained until the present time unchanged.! Tafjord, Nonvay. The rock from Tafjord, Norway, as seen in a section purchased from Richard Fuess, Berlin, is composed principally of rounded grains of olivine, with some enstatite, cof- fee-brown picotite or chromite, and a little magnetite. The structure is essentially the same as that of the peridotite from Franklin, North Carolina. The form and arrangement of the enstatite are very similar to those of the talc in No. 5134. Mohl describes this rock as being similar to the one from Eodfjeld, but with less enstatite, and some magnetite. \ * Am. Phil. Soc. Proc., 1873, xiii. 361-406 ; 1874, xiv. ; 1SS2, 216-218, 381-404; Quart. Jour. Geol. Soc., 1874, xxx. 303-306; Geol. of North Carolina, 1875, vol. i. 129-130; Appendix D, pp. 91-97, 102- 107 ; 1881, vol. ii. 42, 43; Am. Jour. Sci., 1872 (3), iii. 301, 302; iv. 109-115, 175-180; 1873. vi. 180- 186 ; Pop. Sci. Monthly, 1874, iv. 452-456 ; Trans. Am. List. Min. Eng., 1878, vii. 83-90. f Proc. Bost. Soc. Nat. Hist., 1S82, xxii. 141-149. See also Science, 1884, iii. 486, 487. } Nyt Mag., 1877, xxiii. 115, 116. TIIK TERRESTRIAL PERIDOTITES. DUNITE. 121 Dtm Mountain, New Zealand. Tim peritlotite (dunite) of New Zealand is described by Hochstetter as a Mesozoic eruptive mass, associated with serpentine and hyperite, also of eruptive origin. This dunite is a crystalline-granular rock, of light yellowish-green to a grayish-green color on the fresh fracture, and weathering to a dirty, rusty, sometimes yellowish, sometimes red- dish-brown color. Fracture uneven, granular, angular, and coarse-splintery. It was found to be composed of granular olivine, holding octahedrons of chromite, with rounded edges. The serpentine was formed by the alteration of the peridotite in situ.* M. K'enard has given a brief description of the microscopic characters of this rock. The section is composed of irregular grains of olivine, but of larger size than those in the St. Paul's peridotite, to be described later. "With this exception, the other micro- scopical characters are the same in both rocks : the fissures, more or less regular, marked by black lines, intense chromatic polarization of the divine, roughness of the surface, etc., etc. The sections of chromic iron in duuite are larger than those in the specimens from St. Paul, but in other respects they present the same features." f Soiidmore, Norway. The thin sections of this rock, according to P>rogger, contain predominating olivine, with (very sparingly) beautiful green smaragdite, here and there a grain of brownish-yellow enstatite, and chromite in little grains. The olivine is fresh, clear-green, and in the sec- tion colorless, and fine-granular. Some grains show one cleavage parallel to the longer direction of the crystals, and another perpendicular to the same. Only a trace of altera- tion to serpentine was observed. The smaragdite is of a green color, fresh, and shows pleochroism. The only two grains in the section were elongated in the direction of the vertical axis, and show cleavage lines running in the same direction. The enstatite occurs in a few scattered grains. They are fresh, brownish-yellow, finely striated, and crossed by cleavage-planes. The chromite appears in little, irregular, rounded grains. This peridotite is associated with and lying in schists, and is called by Brogger an olivine-sdiist. \ Robcrgvik, SkrenaJcJccn, Norway. This rock was described by H. von Mold as composed principally of olivine grains, containing octahedrons of picotite and deep hair-brown, transparent, chromite crystals. Magnetite was present, and some of the olivine grains showed a change to fibrous chry- sotile. Lamellae of fibrous enstatite were seen. Bonhommc, Bhdtenlerg , Vosycs, France. A blackish-green rock, with a rough, splintery fracture, showing a brilliant shimmer from numberless minute points, and traversed in part by many blackish veins. In thin splinters it is clear-green and translucent. In the section the olivine grains are seen to * Zcit. Dcut. geol. Gcsell., 186 1-, xvi. 341-344; Reise dcr Novara, Geologic von Neu-Seeland, pp. 217- 220. f Report Cliiillrnircr Expedition, Narrative ii. Appendix B. pp. 22, 23. t NCIICS Jalir. Min., 1-^SO, ii. 187-192. N}t Mag., 1877, xxiii. 111. 16 122 PEEIDOTITE. be clear and fresh, but in some points a change to serpentine has taken place. Picotite and a reddish garnet (?) were observed. The other accessories were a few plates of amphibole minerals and iron ores.* KarMaitcn, Austria. Tschermak describes a grayish-green, fine-grained rock from this locality, as com- posed of olivine, united with serpentine, grass-green srnaragdite, and little, black, pitch- like, or semimetallic grains of picotite. f Tron, Oesterthal, Norway. This is similar to the serpentine from the Andestad See to be later described. The olivine grains are changed, along their boundaries and fissures, into a chrysotile. This is in part of a platy-granular structure, and part composed of parallel fibres. In some por- tions grains of olivine with unaltered centres are to be seen. Considerable magnetite was observed. Enstatite is comparatively rare, and when present contains some picotite grains and crystals, a few of which were seen in the olivine.J A section of this rock obtained from R Fuess is entirely altered to serpentine. The gray, serpentine groundmass is traversed by bands of ferruginous and gray material, resembling closely those represented in figures 1, 2, and 4 of Plate V. Dark-brown, trans- lucent picotites were observed scattered through the serpentine, their borders jagged and opaque, probably as a result of alteration. The serpentine is filled with minute black grains of some iron ore. ffeiersdorf, Saxony. According to Dathe, the Heiersdorf rock is medium grained, containing pale-red gar- nets, and showing under a lens quartz and feldspar, with light-greenish and brownish olivine, as well as black, lustrous crystals. The principal portion of the section is oliviue. This is seldom fresh, but generally cloudy or altered to serpentine, forming the usual net- work, and containing some dust-like ore. The olivine contains some picotite or chromite grains. Plates of magnesian mica occur in the neighborhood of the garnet and ore particles. The garnets are of the size of a pin's head, and are somewhat altered. The majority are entirely changed from the singly-refracting garnet substance to a doubly-refracting, radi- ately-fibrous material. This has a pale-blue aggregate polarization color, but in common light is greenish and feebly dichroic. The minority of the garnets have a small alteration zone surrounding them, of colorless fibres, probably asbestus, arranged perpendicular to the garnet boundary. Light-brownish zircon grains also occur. Ronda Mountains, Spain. The serpentine of the Fionda Mountains, covering an area of nearly 600 square miles has been described as eruptive by Joseph Macpherson. || With the serpentine were * Bruno Weigaud. Mm. Mirth., 1875, pp. 186-192. f Sitz. Wien. Akad., 1867, Ivi. 275-279. { Nyt Mag., 1877, xxiii. 120, 121. Neues Jahr. Min., 1876, pp. 227-229. || On the Origin of the serpentine of the Ronda Mountains, J. Macpherson, Madrid, 1876, 20 pp. 2 plates. THE TERRESTRIAL PERIDOTITES. DUNITE. 123 found imbedded large masses of peridotite. The peridotite is irregularly disseminated through the serpentine, showing an intimate connection of the two. The peridotite is found to be composed of olivine grains, traversed by numerous fissures, and containing irregular fragments and octahedrons of picotite. The rock itself usually varied from a greenish-gray to various shades of green. The serpentine is generally of a dark-green color, traversed frequently by veins of chrysotile, and not uncommonly charged with crystals of diallage. It is said that in some places the serpentine " is traversed by great parallel planes of fracture, which at first sight might be mistaken for stratification." The alteration of the olivine takes place along the fissures, the iron separating in the serpentine as magnetite and chromite. This serpentinization gradually extends until only small grains of olivine are left, and then on until the entire rock is altered to serpen- tine. A perfect and gradual transition was traced from the beginning of the process to the complete transformation. The alterations are shown very well in the figures accom- panying Macphersou's paper. Serrama de Honda, Spain. This rock, according to Macpherson, is of a clear, greenish-gray color, with a lustre between a greasy and vitreous. The section is composed of a crystalline-granular aggre- gate of olivine fragments, containing numerous picotite grains. The olivine shows brilliant polarization colors, and sometimes a striation parallel to the plane of extinction, while it is traversed by irregular fissures.* St. Paul's Hocks. These rocks were described by Darwin as unlike any rock he had met. He states : " The simplest, and one of the most abundant kinds, is a very compact, heavy, greenish- black rock, having an angular, irregular fracture. . . . This variety passes into others of paler-green tints, less hard, but with a more crystalline fracture. . . . Several other varie- ties are chiefly characterized by containing innumerable threads of dark-green serpentine, and by having calcareous matter in their interstices. These rocks have an obscure, con- cretionary structure, and are full of variously colored angular pseudo-fragments. . . . There are other vesicular, calcareo-ferruginous, soft stones. There is no distinct strati- fication, but parts are imperfectly laminated, and the whole abounds with innumerable veins, and vein-like masses, both small and large." Darwin states that the rock is not of volcanic origin not necessarily meaning by this anything more than that it was not a modern eruptive formation like that of the other islands visited.f These rocks being the haunts of birds, a phospatic incrustation had been formed on part of the surface, and Professor Wy ville Thomson states " that they look more like the serpentinous rocks of Cornwall or Ayrshire, but from these even they differ greatly in character. . . . Mr. Buchanan is inclined to regard all the rocks as referable to the ser- pentine group. So peculiar, however, is the appearance which it presents, and so com- pli'tdy and uniformly does the phosphatic crust pass into the substance of the stone that I felt it difficult to dismiss the idea that the whole of the crust of rock now above water might be nothing more than the result of the accumulation, through untold ages, of the * Anal. Soc. Esp., Hist N.it., 1879, viii. 251, 252. t Volcanic Iblands, 1851, pp. 31-33, 125. 124 PERIDOTITE. insoluble matter of the ejecta of sea-fowl, altered by exposure to the air and sun, and to the action of salt and fresh water." * According to Rev. A. Eenard, the rock is composed essentially of very small olivine grains similar to those of the New Zealand dunite. Fluid cavities were also observed. Chromite (picotite) is abundant in irregular, generally lenticular grains, of a brownish- yellow color. Eeuard further described a pale green mineral of irregular outline, and a cleavage forming an angle of 124, which he assigned to an amphibole mineral. Knsta- tite in. colorless or clear greenish-yellow sections was observed, possessing an evident lamellar structure. A structure seen in the sections by Eenard was regarded by him as a fluidal structure.! In a later publication, M. Eenard seems to have abandoned his idea of the eruptive origin of these rocks, and inclines to the view that they are formed from crystalline schists, the supposed fluidal structure being really schistose structure instead. He regards this peridotite as remarkably fresh and unaltered. Color, " blackish-gray, bordering green, which when deep looks perfectly black." Its component minerals, as determined by M. Eenard, are olivine, chromite, actinolite, enstatite, and a pyroxenic mineral For a fuller description the reader is referred to the original papers. J M. Eenard thinks that the association of olivine rocks with schists proves their similar origin, and therefore much peridotite is sedimentary ; overlooking the fact that a region of eruptive rocks is one in which the sedimentary rocks are most likely to become schistose. Furthermore, many eruptive rocks are schistose, through secondary changes in them after eruption. Again, many eruptive rocks have associated with them ashes and other frag- mental material of eruptive character, as well as sedimentary deposits, all of which brings into intimate relations metamorphosed eruptive rocks and schists. This is a case to which the principles earlier given in this volume apply. It is especially difficult to see how denudation could take place to the great depth in the ocean required when, as M. Eenard admits, there is no evidence of depression. Two specimens of this rock were kindly sent me by Mr. John Murray, of the Chal- lenger Expedition. One shows on the fracture a dark grayish-green color, and as M. Eenard remarks, closely resembles a quartzite. Weathers to a yellowish and brownish- gray. The section is seen to be composed of olivine, enstatite, diallage, picotite, chromite or magnetite, pyrite, actinolite, and serpentine. M. Eeuard remarks that the minerals have their longer axes placed parallel with the supposed schistose or fluidal structure. In this section the larger grains stand in every direction, some of the olivine grains having their longer axes exactly at right angles to one another. No structure has been observed by me that I should regard as schistose. A slight schistose appearance has been produced in my judgment by the secondary altera- tion of the rock. Fortunately, one of the specimens sent me is of the rock said by M. Eenard to be entirely fresh and unaltered. He also states that the structure of this rock is peculiar, and unlike that of other olivine rocks. In one section a portion of the rock is only slightly altered, and this portion shows the common structure of peridotites. The main mass of the rock, described by M. Eenard as the groundmass, is in my opinion greatly altered, and contains only the remnants of the original minerals, surrounded by their alteration products. M. Eenard regards this groundmass as composed entirely of * Voyage of the Challenger, ii. 100-108. t Neues Jahr. Min., 1879, pp. 389-394. J Report of tlie Scientific Results of the exploring Voyage of II. M. S. Challenger, 1873-76. Narrative, vol. ii. Appendix B., 29 pp., 1 plate ; Description Lithologique dcs llecifs des St. Paul, extrait des Annales de la Societe beige Microscopic, 1882, 53 pp. & TJIK TKRUKSTHIAL PKPJDOTITES. SAXON1TE. 125 olivine grains, but of this I have grave doubts. The characters as seen microscopically do not appear to me to be those of ordinary olivine, but rather those of one or more min- erals of secondary origin. That this groundmass is of secondary origin, for the most part, is shown by its occurrence along the fissures in the unaltered olivines, by its relations to the minerals which it surrounds, which are the same as those existing in other rocks between thu original minerals and their secondary products, and by the secondary schis- t"-' 1 structure. In such cases as these much depends upon the experience and especial kind of work that the observer has done, and unfortunately such evidence cannot be placed in words so as to enable others to judge of its correctness. It is contrary to the laws of physics and chemistry that a mineral in altering should produce itself again there is rather a passage from an unstable compound in the condi- tions in which it then is, to one more stable in the same conditions. If I am right regard- ing this alteration of the olivine the resulting mineral or minerals must belong either to another variety of olivine or to a distinct species. The actinolite, chromite, picotite, magnetite, pyrite, and serpentine, I regard in this case as secondary products in the rock, and not original ones. As said before, in places the section shcjws the olivine unaltered, and having the same relation between the grains that exists in other rocks when the granular structure is due to crystallization from an igneous magma, and not from detrital action. M. Eenard has pointed out that the actinolite is more abundant in the fine groundmass than elsewhere in the sections, which is in accord with my view of their origin. One section shows at one end that it is composed chiefly of a confused mass of pale-greenish mouoclinic crystals, showing cross fracture, and which are here referred to actinolite. An examination of sections from the more highly altered rock shows that on further alteration the fine grouudmass becomes changed from a clear to a dirty-yellowish one, but slightly polarizing. The hand specimens sent me bear evidence that they are surface and weathered specimens to which probably much of the difficulty in their study is due; for, judging from M. Eenard's descriptions, he had similar specimens to mine. In this I would by no means judge of what M. Ilenard saw, but only of the sections that I have myself studied. It is to be hoped that should these rocks ever be visited again great pains would be taken to procure specimens as deep in the solid rock as it is possible to obtain them.* VARIETY. Saxonite. Russdorf, Saxony. Dathe described a peridotite from Ilussdorf, Saxony, as fine-grained, and of a light- '_:iveii color. Olivine formed the essential portion of the rock-mass. This mineral was slightly altered on its edges to a granular substance of a light-yellowish to brownish color ; aK, along the fissures the olivine grains are changed to a light-yellowish, almost homoge- neous mass. Inclosed in the olivine are black octahedral crystals of picotite or chromite. The enstatite shows in colorless, finely-striated sections. Olivine in small grains and small black needles was observed inclosed in the enstatite.f Northern Norway. Holland describes some of the peridotites from Northern Xorway as composed of fresh olivine, containing picotite, together with cnstatite and grains of iron ore. Serpentine Science, 1883, i. 590-59:2. t Ncues JaLr. Miu., 1876, pp. 233-235. 126 PERIDOTITE. from this region was found composed of serpentine, with olivine fragments, and magne- tite. Another serpentine rock contained only serpentine, diallage, and magnetite.* T/iorsvig, Norway. This rock is stated by Mohl to contain 60 per cent of olivine, 30 per cent of eustatite, and 10 per cent of anorthite and magnetite. The olivine and anorthite were in grains, and the enstatite in table-like forms, without crystalline contour.f BirJccdal, Norway. From Birkedal, Norway, according to Mohl, was obtained a peridotite composed of olivine and enstatite, with some magnetite, chromite, mica, and anorthite the latter mineral composing about 10 per cent of the rock-mass.J Hovden, Horningdal, Norway. This peridotite, according to Mohl, is composed of olivine grains and enstatite plates, with magnetite and brown mica. The enstatite is in part of a light yellowish-gray, and in part a very strong nacarat color. It is cut through by parallel fissures, is fibrous, and contains many loose aggregates of brown needles and laminae. Rodfjeld, Norway. Dr. H. von Mohl described a rock from Rodfjeld, Murusjo, Norway, as made up of olivine grains, enstatite, and a little ledge-formed feldspar. The olivine in places is described as suffering a total change to chrysotile. || Andestad See, Aure, Nonvay. This stone, according to Mohl, is composed of 75 per cent of olivine in angular grains, 20 per cent of enstatite and tabular-formed aggregates, and 5 per cent of chromite in granular aggregations. Only a small portion of the olivine remains clear and fresh. Around the contour of the freshest grains wind strings of a dirty greenish-yellow chrysotile. The grains them- selves are sometimes of a dirty grayish-yellow color or cloudy, and show aggregate polar- ization. Here and there a grain is entirely changed to a nearly opaque liver-brown serpentine. The enstatite is nearly colorless, beautifully cleaved, and here and there is finely fibrous the fibres being parallel. ^[ In part, this rock is so far changed to serpentine, that only here and there do the olivine grains show any clear central portions remaining. The enstatite remains in part as fresh as in the preceding, except in its cross fractures, which are filled with chrysotile. In part, the enstatite is completely serpentinized, but recognizable on account of its platy pores and its parallel fibrous structure. The chromite remains unchanged. *' A section of the Andestad- See peridotite, purchased from Eichard Fuess, of Berlin, * Nencs Jalir. Miu., 1879, p. 422. } Nyt Mag., 1877, xxiii. 116. || Nyt Mag., 1877, xxiii. 113, 114. ** Nyt Mag., 1877, xxiii. 119, 120. f Nyt Mag., 1877, xxiii. 115. Nyt Mag., 1877, xxiii. 110. U Nyt Mag, 1877, xxiiL 118, 119. THE TERRESTRIAL PERIDOTITES. SAXONITE. 127 lias the following characters : A yellowish-green groundinass, holding several crystals of enstatite. Under the microscope the section is seen to be formed by a serpentine plexus holding dlivine, enstatite, and chromite. The olivine remains only in small grains, sur- rounded by the serpentine, to which the remainder of the olivine mass has been changed. The olivine is generally very pure and clear, but its fissures are traversed by the serpen- tine ; grains, even some little distance apart, showing in polarized light that they are por- tions of the same crystal. Figure 4, Plate IV., shows the structure of this section. The greenish portion repre- sents the serpentine, the grayish-white portion at the upper part of the section is the partly altered enstatite, the white grains inclosed in the greenish serpentine mass are oli- viue, and the dark grains are chromite. Lctnycnbcrff, Saxony. A dull, black, serpentine mass, holding numerous brownish-black bronzite (enstatite) crystals. In the thin section the bronzite crystals show an extraordinarily fine, wavy, fibrous structure, parallel with the extinction plane. It contains arranged along the planes of the fibres little opaque needles, and pellicles of hydrous oxide of iron, and is par- tially altered to a feebly doubly-refracting substance serpentine. Sometimes the crys- tals are cloudy and altered bastite. The olivine has been altered to serpentine, having the usual maschen texture. Magnetite (?), and little crystals of chromite (?) were also observed.* Calknberg, Saxony, This rock has a blackish-green to brown color, and contains little bronzite crystals. In the section the olivine is seen to have been replaced by serpentine, with the usual network structure. The bronzite is also more or less altered, and chromite, hematite, and other iron ores were observed.! The Ziegclei, between Russdorf and Meusdorf, Saxony. A leek-green serpentine, containing bastite (enstatite) crystals. The section shows the mesh structure of serpentine divided from olivine, and fibrous-bastite (enstatite) with chromite and other iron ores. $ Fain LuJca and Fatu Termanu, Timor. This rock, according to Wichmann. is of an oil-green to blackish-green color, and holds brouzite and chromite. Under the microscope the serpentine shows the mesh struc- ture, indicating its alteration from olivine. The meshes are light-green to colorless, and the interstitial spaces of a brownish-green color. The bronzite (enstatite) in the section is colorless, and free from all inclusions, except secondary products. Rofna, Alps. A compact, dark, purplish-green rock, containing folia of enstatite, having a jointed, crushed structure, with the sides coated with greenish serpentine, and presenting a schis- Datho, Ncucs Jahr. Miu., 1876, pp. 338, 339. f Dathe, Neues Jabr. Min., 1876, pp. 339-341. J Dnthr. Nnirs Jahr. Min., 1876, p. 339. Jaarboek van bet Mijnwezen in Nederlandsch Oost-Indie, 1882, pp. 211-213. 128 PEKIDOTITE. tose aspect. Tlie section shows a reticulated network of opacite, with interspaces having a fibrous border and a granular centre of serpentine. The section further contains some enstatite altered to serpentine, magnetite, and a little picotite, or chromite, and hematite. This is regarded as an altered olivine-enstatite rock. Further examination of these Alpine serpentines showed that they were either derived from rocks of this character, or else from olivine-augite-eustatite rocks.* VARIETY. Lherzolite. Lake Lhcrz, France. The famous Iherzolite occurring about Lake Lherz, and at various localities between that lake and Vicdessos and Sem, in the department of Ariege, in the Pyreneean region of Southern France, has been described by Professor T. G. Bouney as a crystalline aggregate of olivine, enstatite, and diallage (diopside), with some picotite ; the texture varying from a finely to a coarsely granular. Color on the fresh fracture, a dark greenish-gray or olive- green. The rock on close inspection shows specks of emerald-green diallage, waxy look- ing, dull-green serpentine, resinous, pale-brown enstatite, and minute grains of picotite, inclosed in the predominant dull-colored, or glassy, olivine mass. The sections are grayish to water-clear aggregates of olivine, enstatite, and diallage, holding picotite. The section is traversed by a network of fissures, and is thus coarse or fine-granular in different portions. The oliviue is in rounded, water-clear, more or less irregular grains, and is the predominant mineral, forming, according to Zirkel and Bonney two-thirds of the whole mass of the rock. The enstatite is clear, colorless, and sometimes shows a slight, silky texture. The diallage, like the enstatite, is in irregular fragments, sometimes clear and transparent, and at others shows a faint tinge of green. Both it and the enstatite are often feebly dichroic, varying from colorless to various pale shades of green. Sometimes the diallage varies simply in the depth of the green tint. These min- erals are not to be certainly distinguished one from the other, except by their optical characters. The picotite occurs in coffee-brown, irregular masses and grains, the latter often grouped together in little masses, scattered along from the ends of some larger mass. The color is sometimes a yellowish-green, and Professor Bonney describes some as being of a deep olive-green. I should regard the picotite as being the first formed mineral, instead of the last, as he regards it. In some portions of the sections serpentine has been formed along the fissures, showing fibrous polarization, the fibres sometimes lying parallel, sometimes perpendicular to the walls. Near these serpentine veins the olivine is dark- ened along its fissures, apparently from the separation of magnetite or chromite in a fine powder. In some cases these black grains are united into irregular, branching, spiney masses. Masses of these black aggregations are seen arranged in the centre of the vein- lets of the serpentine, like islets in a stream. Professor Bonney, in his sections, was able to trace the alteration of the oliviue to serpentine, one of his sections showing a network of serpentine veins surrounding and penetrating the other minerals. In the sections before me, the olivine is in some cases changed to a pale-greenish serpentine, holding minute aggregations of the ferruginous grains. These serpentine masses are generally iso- tropic, although showing in a few points the fibrous aggregate polarization of serpentine. * Bouncy, Geol. Mag., 18SO (2), vii. 538-542. THE TERRESTRIAL PERIDOTITES. LHERZOLITE. 129 This isotropic character of the early stages of the alteration-products of minerals, has been frequently observed by the present writer in the case of many other minerals. The sections herein described are of two slides, from Voigt and Hochgesang, purport- ing to come from Vicdessos (European Collection, Nos. 71 and 165). Some additions have also been made from the excellent description of Professor Bonney, to which the student is referred.* This Iherzolite was regarded by Bonney as undoubtedly eruptive, on account of its observed relations to the adjacent rock.f Scrrania dc Honda, Spain. This rock, according to Macphersou, has a greenish groundmass of olivine, holding emerald-green diopside. Under the microscope it is seen to be composed of olivine, enstatite, and diallage (diopside). The diallage is of a clear green color, dichroic, and has a fibrous structure. The olivine is clear and fissured, but shows in places a partial change to serpentine. The enstatite resembles the diallage in its general characters, but Las a yellowish color. Picotite is common.} Italy. Numerous peridotites Iherzolites and serpentines have been described from Italy by tin; Italian lithologists, particularly by Professors Alfonso Cossa and Torquato Tara- melli. These appear to be composed principally of olivine, enstatite, diallage, and picotite, and their secondary products. Most of the serpentines seemed to have been formed by the alteration of the Iherzolite variety of peridotite. Cossa's work contains many valu- able chemical analyses of the olivine rocks which have been tabulated, and for the general descriptions and plates the student is referred to Cossa's Eicerclie Chimiche e Microsco- piche su Eoccie e Mineral! d' Italia, Turin, 1881 ; and to the publications of the "Accade- inia dei Lincei" of Rome. Ultcnthal, Tyrol. A coarse, granular, greenish-white rock, according to Sandberger, holding bronzite, chromdiopside, and picotite, in grains and rounded octahedrons. A fine-grained variety shows a schistose structure, and holds rose-red and deep blood-red pyrope. This rock is altered in part to serpeutine. Rilcjc between Indian and Dear Valleys, Colusa Co., Col. 3001. A yellowish and grayish-brown groundmass, containing porphyritically enclosed somewhat bronze-like crystals of eustatite and diallage. Under the lens the groundmass shows a greenish network, holding a yellowish or gray substance between the nii'shes. Section : a greenish-white crystalline mixture of olivine, enstatite, and diallage. * Geol. Mag., 1877 (2), iv_59-f>4. f See also Charpentier, Journal des Minos, 1S12, xxxii. 321-340 ; Essai sur la Constitution G^ogno- stiq.ie iles IWnees, 1^:1, pp. il.'i-JUl.. Ann. Pliysik, 181 1, Ivii. 201-208; Delam6thcric, Tlicorie cle la Torre, 17!7 (3d nl.), ii. 2sl, 2S2; Le?ous dc Mineralogie, 1S12, ii. 20(5, 207; Picot dc Lapeyrouse, Mem. \< M|. Toulouse, iii. 410; Lelicvre, Journal dc Physique, 1787, xxx. 397, 398; Vogel, Journal des Mines. 1813, xxxiv. 71-74; Zirkel, Zoit. Dout. m\. Gesell., ISC,;, x ix. 138-148 ; Damour, Bull. Soc. Geol. France, ISO:! (-2), xix. 413-416; J. Kiilin, Zeit. De.it. -ml. Gesell., 1SS1, xxxiii. 398. J Anal. Soc. E*|i. lli-t. X:it., 1^7'.l. viii. 253-258. Xeues Jalir. Mill., Mid, pp. 449, 450. 130 PERIDOTITE. The whole is traversed by a reticulated series of fissures, which in each mineral partakes of its usual mode of fracturing. The olivine is the predominating mineral. It forms rounded irregular grains traversed by numerous fissures. Larger fissures surround the main olivine masses, these veins being marked by a yellowish-brown central line of earthy ferruginous and serpentinous mate- rial, on each side of which extend borders of pale-green serpentine. The borders are of various widths, and usually ramify in little veinlets of serpentine through the fissures intersecting the olivine individual. In places, the entire olivine is altered to serpentine. The serpentine in polarized light usually shows fibrous polarization, the fibres being arranged perpendicular to the sides of the fissures. The yellowish-brown earthy mate- rial that marks the medial line of the main veins has entirely replaced the olivine in some portions of the section, giving rise to brownish patches. The serpentine is filled, along various planes and especially along the central line of the veins, with innu- merable minute fluid cavities, so minute that even magnified over nine hundred diame- ters they remain as fine black globulitic specks, totally reflecting the transmitted light. Occasionally one larger than the rest shows the narrow outline of the common full fluid cavity. The enstatite is in elongated crystals and irregular grains, traversed by the usual fine, fibrous cleavage. The surface of the crystals is somewhat smooth and silky, and the principal cleavage is broken occasionally by fractures running obliquely across the crys- tals. The larger enstatites frequently show a greenish fibrous alteration extending along the fissures and sometimes reaching the main body of the crystal. The diallage is, like the enstatite in most of the sections, clear and colorless. It can generally be distinguished from the latter mineral by the roughness and irregularity of its cleavage, owing to the acute angle at which two of the cleavages meet in most of the grains. Like the smaller enstatites, the diallage is in irregular grains and masses, and both occasionally contain rounded grains of olivine, and crystals and grains of picotite. In one or two cases grains were observed showing the cleavage of augite. Some of the diallage plates have an earthy-white or cloudy appearance, marking a certain amount of alteration. Sometimes both the enstatite and diallage are traversed by serpentine veins, and the smaller grains surrounded by that mineral. Picotite occurs in yellowish-brown octahedrons, as well as in irregular masses, opaque for the most part, but translucent and of a yellowish-brown color in places. How much of this might properly come under the head of chromite can not be told. In the yellow- ish-brown serpentine veins are arranged grains showing the lustre of magnetite, which mineral is also seen in some portions of the before-mentioned opaque irregular masses of picotite (?). The microscopic structure of the rock is shown in figure 1, Plate V., which indicates the grayish, fissured, partly altered olivine and eustatite grains, the dark picotite grains, and the brownish veins traversing the rock-mass. This rock was described by the collector, Mr. W. A. Goodyear, as metamorphic, but with the stratification generally almost obliterated. Mr. Goodyear probably took a some- what banded arrangement of the minerals, as observed in No. 3002, and a tendency to split into platy masses, for stratification. Since both of these are common in eruptive rocks, the latter showing especially on alteration and weathering, further evidence is required upon the subject. Microscopically and lithologically they belong to rocks which the best evidence pronounces to be eruptive. It is to be hoped that future geologists, in visiting the locality, will endeavor to settle the question of the origin of these most interesting THE TERRESTRIAL PERIDOTITES. LHERZOLITE. rocks by an examination of their relations to the associated rocks. Of the occurrence Mr. Goodyear states: " The great mass of the rock throughout the whole ridge consists of, apparently, a serpentinoid matrix, filled with foliated crystals of a hard, green mineral, which I suspect to be pyroxene, forming a rock similar to that of which large quantities occur near Guenoc and Coyote Valley. But there are also immense quantities of serpen- tine without these crystals."* The associated rocks, according to Mr. Goodyear, were some hard metamorphic sand- stones, and a few shales. No. 3002 is from the same locality. This has a reddish-brown groundmass, holding crystals of enstatite and diallage. The same reticulated network is observed in the groundmass as in the preceding, but the in- closed portions are of a yellowish- or reddish-brown color. A roughly banded appearance is produced by a somewhat linear arrangement of the enclosed crystals. Both this and the preceding are surface specimens. Some of the crystals in No. 3002 show the well- marked characters of bronzite. Section : this is composed of a reticulated network of serpentine veins, holding rounded and irregular grains of olivine, enstatite, and diallage ; while larger enstatite crystals are porphyritically enclosed. This rock was evidently once a crystalline-granular mass of olivine, enstatite, and diallage, but now it exhibits a stage of alteration somewhat in advance of that shown in No. 3001. The same reticulated network of serpentine, with the same reddish-brown medial line, is to be observed as in the preceding ; in fact, the structure of the two rocks is identical. The serpentine ex- tends from the medial line of the veins inward along the fissures, until only portions of the original minerals are left surrounded by it. In many cases the serpentine has re- placed the entire mass of the rock, but still retains the marks of the fissures along which the alteration took place. The serpentine extending out from the reddish-brown portion of the veins is of a pale greenish-yellow color, and shows fibrous and aggregate polarization the fibres, as usual, being perpendicular to the sides of the vein. While part of the olivine lying inclosed in this network is unchanged, much of it has been altered to a reddish-brown serpentinous mass like that forming the centre of the veins. In many cases this last extends only partly through the olivine grain leaving a central portion of unchanged olivine, but in others the alteration is complete. This reddish- brown alteration shows a tendency to extend in fibres parallel to the crystallographic axis, or along the latent cleavage planes. The general characters given in describing the minerals in No. 3001 hold good here. The enstatite is more highly altered to the greenish fibrous product, while it is frequently crossed by fissures at right angles to the principal cleavage. The serpentine veins in this and in the diallage are more abundant and pronounced than in No. 3001 ; but these minerals evidently are more slowly altered than the olivine. Of the eustatite and diallage, the former is the more readily changed. Picotite or chroinite occur as before, but in somewhat larger masses. Figure 2, Plate V., shows the general microscopic structure of this rock, the dark to black portions representing the iron-ore grains ; the white portions are the unchanged oli- vine, the orange-brown and yellow colors mark the differently altered portions of the olivine (serpentine), while the dark-brown bands are serpentine veins like those which are shown to some extent in figure 1 of this plate. Figure 3, Plate V., is from the same rock, and shows the structure of the partly altered enstatite. The main portion of the figure is that mineral with its cleavage lines * Unpublished Report made to Professor J. D. Wliitncy. 132 PEEIDOTITE. and alteration-products represented by the gray and brown lines running from top to bottom. The enstatite crystal is crossed from right to left by a yellowish serpentine vein connecting two portions of the altered olivine mass represented by the mixed brown, yellow, and white. The dark grains are the iron ores, or picotite. Figure 1, Plate VII., represents an enstatite crystal from the same rock, in a more highly altered condition. The primary cleavage runs from right to left, and the secondary from top to bottom. The greenish color shows the earlier stages of the alteration, and the yellow color the following or serpentine stage, although part of the serpentine mate- rial may have been brought in from the surrounding olivine mass not shown in the figure. Foot of divide between Round Valley and Bullfrog Creek, Inyo Co., Cul. 3003. A compact oil-green groundmass, holding bluish-black and bronze-like crys- tals of enstatite. The rock is traversed by a few veins of pale-green serpentine, while a chrysotile vein occurs at one end. Section : a yellowish-green groundmass, holding porphyritically enclosed some dark enstatite plates. The groundmass shows under the microscope the same reticulated net- work of veins as that seen in 3001 and 3002, the veins being readily distinguishable both in common and polarized light. While the structure remains in general the same as in 3001 and 3002 the entire groundmass is changed to serpentine : that is, it is a dis- tinct pseudomorphous replacement by serpentine of all the essential structural character- istics of the preceding rocks. Even black opaque masses are seen having all the structural features of the picotite of Nos. 3001 and 3002. Much magnetite or chromite is seen scattered throughout the grouudmass, or collected into open aggregations. The enstatite in some cases retains its usual polarization charac- ters, with the well-marked cleavage. In others it has been so highly altered that only traces of the cleavage and the orthorhombic extinction in polarized light remain of its usual diagnostic features. All the enstatites are filled with grains of magnetite, which in some crystals are arranged along the cleavage lines. The powder of the enstatite crystals is magnetic, and it is to the magnetite that their bluish-black color is due. The magnetite is regarded as a product formed during the conversion of the rock into serpentine. The evidence afforded by the microscopic structure of this rock, it seems to me, is proof posi- tive that this serpentine was formed from the metamorphism of a peridotite, the beginning of which change is to be seen in No. 3001, and still further advanced in No. 3002. The general structure of this section is shown in figure 4, Plate VI., which displays an altered enstatite crystal with its secondary magnetite, surrounded by the serpentine replacing the oliviue. Mohsdorf, /Saxony. This rock, according to Dr. E. Dathe, is compact, blackish-green, and contains crystals of diallage and enstatite, which show a mother-of-pearl to silky lustre, and a light-yel- lowish color, while they are finely striated. The principal material of the section is olivine, part of which is in large rounded grains with few fissures, and part in smaller grains, traversed by cracks, and more or less altered to a greenish-fibrous serpentine. The olivine contains little octahedral crystals of chromite or picotite, with rounded angles. The enstatite is in light-greenish, elongated sections, sometimes holding olivine grains, and traversed by cleavage lines parallel to 010. Diallage also occurs, recognized by its opti- THE TERRESTRIAL PERIDOTITES. LHERZOLITE. 133 cal relations and cleavage. Greenish, crumpled chloritic plates and fibres, forming rosette- like a.uuiv-atrs, are associated with the garnet as an alteration-product. Also, brownish plates, with the strong dichroisin of biotite, were seen. Besides the secondary chlorite and biotite, magnetite and hydrous oxide of iron have been produced by the alteration of the garnet. The latter mineral is next in abundance to the oliviue, and in its fresh state is traversed by fissures.* Mod/iait 'e the granules still unchanged in the greenish secondary serpentine material, which in part replaces the original olivine. The brownish portions forming a matrix for the altered olivine are the enstatite and diallage, which for the most part are changed. The bluish band on the right is one of the alteration-borders between the olivine and enstatite. GJfinid, Norway. This, according to Mohl, is principally composed of rounded and obtuse-angled olivine grains, which form from sixty per cent to seventy per cent of the mass. Along the contours and fissures the olivine is changed to a bright leek-green, gray-green, and grass-green chrysotile, whose fine fibres are arranged partly across, and partly parallel to, the direction of the veins. The centre of these chrysotile veins is generally filled with a fine black line of magnetite or by aggregations of magnetite grains. Some hypersthene or an augitic mineral occurs in the section. This is dichroic, of a chocolate-brown color, but altered in part to a cloudy-grayish and yellowish-white sub- stance, supposed to be a magnesium carbonate.* In a section of Gj^rud serpentine purchased from R Fuess, a gray, sponge-like mass is seen holding the greenish, serpentiuized olivine. Excepting that the alteration has pro- gressed some further, the description of the Christianin peridotite would apply to this section. If the dichroism of the rhombic pyroxene arises from alteration, as I suspect it does, there seems to be no reason for calling it hypersthene, instead of enstatite. Its structure and alteration are shown in figure 4, Plate VIII. Nyt Mag., 1S77, xxiii. 122, 123. 136 PERIDOT1TE. Presque Isle, Michigan. 65. A dark grayish-black to black rock, showing in places the irregular shimmer of enstatite holding olivine. Section : grayish-green, and composed of an irregular mass of enstatite, olivine, diallage, magnetite, and various secondary products like feldspar, viridite, dolomite, ser- pentine, etc. The olivine with its secondary products forms in places the principal portion of the section ; in other parts the enstatite and diallage are the chief minerals ; while the olivine and magnetite are held in grains in the interior. The olivine crystals are comparatively large, but much fissured and altered along the fissures and exterior. The interior portions are clear or smoky, except where the olivine material has been completely changed. The alteration shows in the form of cloudy bands of magnetite traversing the crystal along the fissure lines, while a further change is shown by the for- mation of greenisli and yellowish serpentine along the same lines. The change continues until the olivine is entirely altered. The magnetite usually assumes an irregular grating form or network extending through the serpentine, as well as being arranged in lines which show the former position of the olivine fissures. The enstatite and diallage have a slight tinge of green, and are slightly pleochroic. They are traversed by longitudinal, transverse, and irregular fissures, the latter being more abundant in part of the diallage. They form together an irregular sponge-like mass holding olivine, and thus present a structure not unlike that of the Atacama and Siberian pallasites, in which they play the r6le of the iron. They seem to form the same identical continuous mass, but with a high power the line of union can be faintly seen. It probably would have never been discovered if polarized light had not directed attention to it. The enstatite polarizes with a pale greenish tint differing but little from the natural color, while the diallage shows brilliant hues of mixed yellow, red, and violet. Both are more or less altered along the fissures to a greenish or a yellowish-green serpentinous product, which is dichroic, varying from a green to a yellowish-brown shade. Similar dichroisrn, but less marked, was observed in the serpentine of the olivine. In the highly altered portions of the section are lath-shaped crystals, branching from a centre in a fan- shaped mass. These appear to be feldspars, some of which possess plagioclastic characters. Associated with these occur brown biotite, a little apatite, and some augitic material. The structure of these patches closely resembles that of some diabases. The entire section is traversed in places by a pale greenish serpentine in veins holding dolomite, the latter mineral occurring elsewhere in the section. Some actiuolite was observed. The mag- netite is in octahedrons and irregular grains, as well as in the secondary forms before mentioned. The cloudiness of the olivine seems to be due to magnetite granules. Besides the serpentine, a bluish-green fibrous viriditic product occurs, associated with brown biotite plates in such a manner as to lead to the belief that this product is an earlier stage in the formation of biotite, whicli is evidently an alteration product here. The structure of the enstatite portion is shown in figure 3, Plate VII. 73, from the same locality, is a dark grayish-black to black rock, mottled with minute specks of grayish-white, as well as with pyrite. Weathers to a rusty brown. Section : of a dirty green color, and composed principally of olivine grains and crystals, with magnetite held by a light green mass of enstatite, diallage, and various secondary products. The alteration of the olivine is greater here, as a rule, than in No. 65. The magnetite bands along the fissures are wider, and fewer portions are left showing the THE TERRESTRIAL PERIDOTITES. LHERZOLITE. 137 oliviue polarization. The secondary products are as in the preceding, but more abundant ami well marked. Much less eiistatite and diallage exist here than in No. 65, and they are move highly altered. The interspaces between the olivines more commonly contain pule greenish serpentine, bluish-green and yellowish biotite (?) material, dolomite, mag- netite, etc. Much of the serpentine shows the coarse fibrous laminae so commonly observed in the serpentines described in this volume. In portions of this section and in another slide from the same hand specimen the change of the rock mass to serpen- tine is nearly, and sometimes quite complete, the forms of the olivines being distin- guishable through the arrangement of the magnetite and the serpentine. The general structure of section is shown in figure 4, Plate VII. 67, from the same locality, is composed of the same dark grayish-black rock, which here presents a brecciated appearance on account of its being traversed by rambling veins of light-yellowish serpentine. In the section the rock appears as a dirty greenish mass traversed by greenish-white veins. It is composed of serpentine pseudomorphs of olivine, filled with beautiful dendritic growths of magnetite, as well as with irregular ma -sfs of the same mineral The interspaces contain the various secondary products before described : micaceous (viriditic) material, serpentine, magnetite, feldspar, dolomite, etc. The veins are composed principally of dolomite grains and serpentine, the former predominating. 74, from the same locality, is much like No. 65, but the grayish spots are more abundant. Under the microscope it is seen to be composed of a coarsely fibrous lamellar serpentine traversed by the irregular network of magnetite so common in the serpen- tinized peridotites. It contains a little dolomite and one plate of a micaceous mineral was observed. This was feebly dichroic, greenish and yellowish, extinguished parallel to the nicol diagonal, and polarized with a beautiful purplish-blue tint. It presents a fine micaceous cleavage parallel to the line of extinction, and it is probably partially formed biotite. 71, from the same locality, is a grayish-green rock traversed by grayish-white veins of dolomite, which give to it a rude appearance of foliation. The rock contains a number of reddish-brown patches formed from a breccia of the decomposed rock held by minute reticulated veins of dolomite. The section is composed of yellowish and bluish green, and reddish-brown pseudomorphs of oliviue held in a granular mass of dolomite. Crystals and grains of magnetite are scattered throughout the rock. The olivine in the greenish pseudomorphs has been entirely replaced by serpentinous and ferruginous material with dolomite, the first predominating. The reddish-brown pseudomorphs have the ferruginous material the most prominent, and it is these pseudomorphs which form the reddish- brown patches before referred to. The fissures of the olivine are represented by ferruginous and sometimes by dolomitic bands, and these bands can sometimes be seen in the dolomite, showing the form 'of the pseudomorph when the latter has been almost entirely replaced by dolomite. A portion of the structure of the section is shown in figure 5, Plate VII. /the gray groundmass being dolomite and the greenish patches the paeudomorphs after olivine. 69, from tin; same locality, is a pale oil-green serpentine, banded and spotted with dark and light brown. The section is composed of a granular and fibrous mass of si-i|>rntine and dolomite, with ferruginous and earthy material, all holding brownish- yellow uarthy pseudomorphs after olivine, which are traversed by the ferruginous Viands rejnvseiiting the olivine fissures. These pseudomorphs are wanting in portions of the section. Much of the serpentine shows the fine fibrous polarization of chrysotile. 18 138 PERIDOTITE. 66, from the same locality, is a dark greenish-brown rock traversed by a network of oil-green serpentine veins, giving it a roughly foliated appearance. The section is very similar in character to that of the preceding. 70 is a dirty green rock coining from the upper portion of the mass at Presque Isle. Section grayish, and composed principally of a granular mixture of dolomite and serpen- tine with some ferruginous and micaceous materials, etc. 72 is from a portion of the Presque Isle peridotite which has been so filled by dolomitic material as to form a vein. The rock is brownish-gray with a slight pinkish tinge, and composed of granular dolomite holding masses and grains of the decomposed peridotite. It presents the usual structure observable in veins formed by the decom- position and the partial removal of the original rock, and its replacement by vein material. This more properly comes later, in the portion of this work in which the vein- stones are described ; but on account of its connection with the previously described peri- dotite it is given here. The sections are composed of a dirty gray granular dolomite, holding patches of ferruginous material, both dark and light yellowish-brown. In places the darker portions show the cherry-red color of hematite, and appear in part at least to replace olivine. The Presque Isle peridotite was microscopically studied by Dr. A. Wichmann, who gave a short description of it under the name serpentine, stating that it consisted only of olivine, serpentine, and magnetite.* No chromite was found, on making proper tests, in the Presque Isle rock, either by Professor Whitney f or myself ;J but Dr. Eominger states that it contains two per cent of chromic iron in small octahedrons readily attracted by the magnet, although he does not remark whether this iron was tested to prove the presence of chromium or not. This peridotite is confidently believed to be eruptive from the following observed evi- dence. On the southeastern side the overlying Potsdam sandstone dips quite irregularly from twenty to thirty degrees southerly. Its strata follow continuously the curve of the underlying peridotite, and even in places form anticlinals. The surface of the peridotite is an irregular knobby one, while it forms as a whole an immense knob. To this knobby structure the layers of the sandstone conform continuously, as layers of blankets would, and they show no signs of deposition against or around the knobs, but rather a structure as if the sandstone layers had themselves been indented and bent by the peridotite itself. The sandstone with its conglomeritic portion for some two or- three feet above the perido- tite has been greatly indurated and changed, showing heat action, particularly that of thermal waters. It is filled with vein and clialcedonic quartz ; and indurated and red- dened as such rocks are known to be when in contact with eruptives of later date than themselves. These indurated portions show, on examination under the microscope, that much of the quartz is a secondary water deposit formed since the deposition of the frag- ments composing the rock. Above this indurated portion comes the ordinary unaltered sandstone. No fragments of the peridotite could be found macroscopically in the field or microscopically in the laboratory in the sandstone. Now the sandstone does not hold such relations to the Azoic rocks of the district when in contact with them, and it seems right to maintain that this peridotite is younger and an eruptive rock, intruded in the form of a laccolite since the Potsdam sandstone was laid .down.|| * Geol. Wise., 18SO, iii. 618. f Am. Jour. Sci., 1859, xxviii. IS. J Bull. Mus. Comp. Zool., 1880, vii. 61. Geol. Mich., 1881, iv. 136. || See Foster and Whitney, Geology of Lake Superior, 1851, ii. 17, 18, 92, 121, 122 ; Bull. Mus. Comp. Zool., 1880, vii. 2, 3, 6, 9, 10, 23, 60-66. THE TERRESTRIAL PERIDOTITES. LHERZOLITE. 139 Sec. 29, T. 48, R. 27. Three and one-half miles northwest of Ishpeming, Michigan. 242. A gray, somewhat fibrous rock. Section: a gray mass traversed by a network of magnetite. It is composed of a light gray and colorless transparent mass of serpentine with some dolomite, and has the usual reticulated arrangement of the magnetite so char- acteristic of the serpentines produced from the alteration of olivine rocks. 241, from the same locality, is a greenish- and reddish-brown rock traversed by green- ish-gray serpentine veins. Weathers light yellowish-green. The reddish-brown color is owing apparently to a ferruginous staining of the serpentine folise. Section is brownish- gray and composed of a pale greenish-yellow serpentine traversed by irregular reticulated magnetite bands, and spotted by irregular ferruginous stains of reddish- and brownish-yellow. While in the hand specimen these stains present the appearance of distinct micaceous folia*, I ain unable by the microscope, either in common or polarized light, to find any structure peculiar to them and distinct from the serpentine, beyond that belonging to ordinary ferruginous stains. The serpentine shows an irregular fibrous and lamellar structure in polarized and common light. 245, from the same locality, is similar to the preceding. Its staining is deeper, and the rock is coated on one side with a chrysotile and dolomite vein. In the section the fibrous structure, the magnetite network, and the ferruginous staining are all more strongly marked than in the preceding. 243, from the same locality, is a greenish-gray rock with the ferruginous staining showing in a few spots only, principally along fissures. The section is gray, and under the microscope is seen to be composed of pale greenish -yellow serpentine with cloudy spots. These appear to be occasioned by a fine magnetite dust, which is generally associ- ated with an approach to crystallization on the part of the surrounding material, which somewhat affects polarized light. Numerous pale greenish scales occur in abundance in the serpentine, and have the polarization characters of talc. Crystals and grains of mag- netite are scattered throughout the section. 235, from the same locality, is a clear translucent green serpentine containing magne- tite grains. It weathers light-colored, even to a chalky-white. The section forms a clear almost colorless mass spotted with crystals and grains of magnetite. The same mineral also traverses the section in the form of a vein. In common light the clear serpentine mass shows fibrous structure, which is beautifully brought out in polarized light. The magnetite appears as a secondary product Associated with these are other specimens of greenish- and reddish-brown serpentine often traversed by dolomite veins. In large masses this dolomitic material with talc oa to have replaced nearly all of the serpentine, giving rise to a rock called locally limestone. Much chrysotile also occurs.* Transylvania, Austria. Tschermak describes a schillerfels f from this region as a dark-green rock with white spots composed of olivine, bronzite, diallage, magnetite or chromite, and a little anorthite. * See further, Bull. Mus. Comp. Zool., 1880, vii. 05, 66 ; Wright, Mineral Statistics of Michigan, 1879, pp. 201-200; Romin-rer, Geol. Michigan, 1881, iv. 137-143. t Herbich appears to class this with eruptive rocks. Verh. Mitth. Natur, Hermaunstadt, 1865, xvi. 173-183. 140 PEEIDOTITE. The olivine is traversed by a network of dark-green serpentine fibres, and the diallage and bronzite are both somewhat altered. Associated is a compact dark-green serpentine hold- ing some chysolite and chromite. Another rock from the same district is of a dark olive- green color, flecked with white spots ; and contains a platy greenish-brown shining diallage, a deep green finely granular mass of olivine, and small white grains of anorthite. The olivine is here traversed by a network of dark-green serpentine.* Fitchtelgebirge, Bavaria. These rocks are composed principally of olivine with enstatite, chromdiopside, augite, and magnetite. The olivine is more or less altered into a serpentine, showing the usual network structure. The enstatite is in elongated, fibrous, brilliant clear wine-green needles, and the chromdiopside in roundish, compact, somewhat fissured particles. The groundmass consists of a mixture of chlorite, serpentine, etc.f A Pebble from the Jaina River, ten to twelve miles N. W. of Ml. Mariana, C/iico, Prov. San Domingo, San Domingo. 252 G. A compact dark-green groundmass holding crystals of brownish pyroxene and traversed by veins of chromite. Section : a gray groundmass holding iron ore and crystals of enstatite and diallage. The groundmass is composed almost entirely of clear beautifully polarizing serpentine, which shows in its structure traces of the bounding planes of the minerals from whose alteration it was derived. A little white plagioclase, traversed by cleavage planes, was observed, portions of which had been rendered gray and nearly opaque by kaolinization. Only a few small fissured olivine grains were observed. The enstatite and diallage can here as a rule be distinguished by their cleavage, the latter being much less regular than the former, and closely like that of augite. Both are in irregular grains, more or less altered to a greenish- and yellowish-brown product. Where the change has progressed far, the ordinary serpentine of the groundmass is the result. Sometimes the serpentine resulting is filled with minute black globules, or with minute microlitic forms, ar- ranged in lines forming definite angles with one another. The iron ore is in part in crystals and part in irregular grains and masses. The structure is shown in figure 6, Plate IV. This rock was collected by Professor W. M. Gabb. Starkenbach, Bluttenberg, Vosges, Frame. According to Weigaud this is soft black rock containing brownish-yellow and brass- yellow crystals. In the thin section the rock is seen to be composed of bronzite (ensta- tite), diallage, olivine, magnetite, hornblende (smaragdite ?), and picotite, with more or less serpentine. The enstatite and olivine are more or less traversed by fissures filled with serpentine. The hornblende is in minute plates, while the bronzite is the predomi- nating mineral.^ * Site. Wien. Akad., 1867, Ivi. 261-274. f C. W. Gumbel, Die palaolitliischeu Eruptivgesteiue des Fichtelgebirges, 1874, pp. 38-41. } Miu. Mitth., 1S75, pp. 192-196. THE TERRESTRIAL PERIDOTITES. LHERZOLITE. 141 Todtmoos, Baden. 5000. The specimen from this locality in the collection is a blackish-green compact one, containing a ff\v disunite and diallage crystals. It weathers to an earthy rusty- brown, showing the network method of decomposition frequently observed in the perido- tites. This with the sections was purchased from Voigt and Hochgesang, Gottingen. One section has a greenish groundmass holding crystals and grains of enstatite, dial- lage, olivine, and picotite. The enstatite is in part clear and unaltered, holding picotite grains, and in part it has suffered a greenish and yellowish serpentinous alteration. The same can be stated of the diallage. Both are in rounded crystals and irregular masses, and show the usual cleavage lines. The olivine when unchanged is in clear grains, the remnants of the original larger crystals ami grains. That a series of these grains now separated by the serpentine bands once formed the same crystalline mass, is shown conclusively by their possessing the same optical orientation. The major portion of the original olivine has been changed to ser- pentine, the structure showing the successive stages of alteration. The serpentine formed first along the fissures has a dividing line indicating the fissure, and on both sides the ser- pentine fibres stand at right angles to that line. The color of this serpentine is generally a light yellowish-green. The interior portion occupying the interspaces left between the network lines above described, is occupied by serpentine of a different shade of green, sometimes lighter, sometimes darker. This serpentine, which replaces the olivine grains before described, shows not only by its color, but also by its structure, both in common and iu polarized light, that it possesses a distinct organization from that of the network, and is distinctively a later product. The serpentine forms the chief portion of the groundmass and is feebly dichroic. While it is usually of some shade of yellowish-green to pale-green, in some cases, especially about the ferruginous products, it is of a bluish- green color, doubtless owing to the ferrous oxide. Some secondary actinolite and talc exist associated witli the pyroxene minerals. The picotite is in coffee-brown and pale- greenish irregular grains scattered throughout the section in the different minerals. The larger grains along their fissures and edges are altered to a black ferruginous product, probably chromite. This alteration sometimes extends nearly, and sometimes quite, through the entire picotite grain. Considerable secondary iron ore exists, which is either chromite or magnetite. Another section has a yellowish-green groundmass containing grains of enstatite, diallage, and picotite, and traversed by veins of talc. The groundmass is a network of serpentine of a pale yellowish-green color, surrounding portions of a deeper green repre- senting the unfissured parts of the olivine, while the meshes follow the fissures. The enstatite and diallage are in places only slightly altered ; but for the most part they are traversed by threads of the serpentine web, and possess a fibrous alteration-structure showing a more or less .aggregate polarization ; yet iu the majority of cases they retain their relative extinction. This serpentine is very beautiful in polarized light. The pico- tite is in irregular fissured grains, sometimes opaque, but more commonly with dark brown to black edges, and with a light brown to dark reddish-brown interior. Much ferruginous material in grains and irregular patches is distributed through the section. This serpentine has been referred by Ilosenbusch to the Iherzolites. 142 PERIDOTITE. From Spur between Deadwood and Poker Flat, Cal. Ill P. A dark-yellowish and brownish-green rock containing enstatite grains and talc scales ; and traversed by light-greenish serpentine veins. Section : a greenish-gray mass flecked with magnetite grains and traversed by a grayish-yellow serpentine vein. The chief portion of the section is serpentinous material, in which besides the magne- tite are scattered the remains of enstatite crystals and a few grains of olivine and diallage. The serpentine varies in color from white to yellowish and green. In places clear white leaves of talc associated with magnetite occur ; while some hematite is to be seen. Along the sides of the serpentine vein before mentioned the section is black with the rejected magnetite. Much of the enstatite contains the same inclusions that the bronzite variety is accustomed to hold. The structure is shown in figures 3 and 6, Plate VI. Levanto, Italy. One specimen described by Prof. T. G. Bonney from this locality is a purplish- or brownish-black rock veined occasionally with dull green, and flecked with crystal- line folia of glittering bronzite, while another specimen is of a more granular texture, greener color, and rougher fracture than the preceding, but otherwise similar. The second rock, in the thin section, is seen to consist chiefly of olivine grains separated by threads of serpentine. It contains opacite, enstatite, augite, and perhaps a little diallage. Opacite [magnetite] occurs in the enstatite and a little picotite was observed. The first specimen was seen under the microscope to have been completely altered, no olivine remaining intact. Much opacite was found, which often forms continuous strings, and is present to a greater or less extent in the grains that were formerly olivine. It forms bauds towards the exterior of the grains, or is disseminated throughout them. Diallage and enstatite are both present, the latter being surrounded by a border of a ser- pentinous mineral, into which are continued the principal cleavage planes, often marked by opacite lines. Thin bands of serpentine indicate the prismatic cleavage.* Near Limni, Euboea. A black splintery rock, which, as described by Becke, contains lustrous bronze-colored grains of enstatite. Under the microscope it shows the evident maschenstruTctur of the serpentine which holds lens-forrned masses of fresh olivine. This groundmass porphy- ritically contains fresh enstatite of a pale brownish color and a marked fibrous texture. This mineral is sometimes altered to a feeble bluish polarizing product. This alteration extends from the exterior along the fissures towards the interior. Diallage, reddish- brown octahedrons of picotite, and secondary magnetite also occur. Similar to this is a rock from Mantoudi, in the northern portion of Eubrea. This is brownish, and contains numerous plates of enstatite in a fine-grained groundmass. No diallage was observed, but the brownish color of the rock is due to brown hydrated oxide of iron. Similar to this is a rock from the district of middle Eubrea, between Chalcis and- Gides, which has a reddish-brown groundmass holding tombac-brown eustatite (bastite). No olivine remains unaltered to serpentine. * Geol. Mag., 1879 (2), vi. 362-371. THE TERRESTRIAL PERIDOTITES. LHERZOLITE. 143 A rock of similar character was obtained between Kuini aud Kastrovolo, in middle Eubcjca, possessing diallage instead of enstatite. The diallage is partly altered into a greenish substance and partly into talc plates. A serpentine from Kami was found to contain much chromite, magnetite, and some green ouvarovite.* Oberlaitf, Luzon, Philippine Islands. A dark blackish-green serpentine-like compact rock, with crystals of clear green dial- lage and brownish enstatite. The principal cleavage planes show a mother-of-pearl lustre. Microscopically the rock possessed the usual mesh structure, and contained mag- netite and picotite.f Lizard District, Cornwall. The serpentines of this district were found to present intrusive relations to the adjoining rocks by Prof. T. G. Bonney. They send tongues and dikes into the latter and hold included fragments of them, while the adjacent rocks at their junction with the serpentine were oftan altered and contorted. The microscopic examination indicated that the serpentine resulted from the alteration of Iherzolite. The following is condensed from Professor Bonney's description of the rocks and sections. The rock from Coverack Cove is a dull mottled, red and green rock with flakes of a silky bronzitic mineral in the green portion. Under the microscope the serpentine forms golden-colored and reddish- aud greenish-brown reticulated veins, which enclose colorless olivine, as well as augite, enstatite, and diallage. Original and secondary iron ores occur. A rock from Mullion Cove has a similar composition and structure, but the alteration of the olivine has pro- gressed further, with a differentiation of the common black ferruginous dust A few small grains resemble picotite. At Gue Graze a similar but more decomposed rock was obtained, which appeared to contain a pseudomorphic product after feldspar. From the Lower Pradanach and the Rill quarries similar rocks to that from Mullion Cove were obtained, but in one from Helston Uoad a little hornblende was observed. The rock from Goomhilly Downs is a banded dull-colored light-greenish serpentine, containing in the section, besides the serpentine, olivine, hornblende, magnetite, and some picotite. A number of other sections were examined, but they are mainly similar to the above, or else have been more highly altered, so that the olivine was entirely changed ; but the reader is referred to the original paper for the particulars.^ Two other areas of serpentine were later examined in the Lizard district, one of which shows excellent junctions and is clearly intrusive in the associated schist. Bonney also re-examined the other portions of the district previously studied by him, and found the strongest evidence of the intrusion of the serpentine into the associated sedimentary rock. From the Troad, Asia Minor. Owing to certain arrangements, and for a consideration, the lithological collection of the Assos expedition has become the property of Professor Whitney, and passed over to * Min. Mitth., 1878 (1), i. 477-485. f Konrad Oebbeke, Neues Jalir. Min., Beilage Band, 1882, i. 499. J Quart. Jour. Geol. Soc., 1877, xxxiii. 884-928 ; 1883, xxxix. 21-23. Phil. Mag., 1882 (5), xiv. 478 ; Quart. Jour. Geol. Soc., 1883, xxxix. 21-23. 144 PERIDOTITE. ray charge. Mr. Diller (who collected the specimens) has kindly consented that I should use his written description of the Assos serpentine rocks, not yet published except in ab- stract,* and it is given below, with a few verbal changes to adapt it to the present work. " Serpentine occurs in the Troad at Qara-dagh . . . derived from the alteration of eruptive rocks ; also about the summit of Mt. Ida in small lenticular masses in talcose schist, and belongs to the stratified rocks; also . . . forming low rounded conical hills near the base of Qara-dagh. The rock is usually of a deep green color, but varies, becoming bluish or reddish, often presenting smooth fibrous surfaces like slickensides, and occasionally an imperfect columnar structure. Although locally uniform, it is gen- erally made porphyritic by a fibrous or lamellar mineral, whose cleavage plates between crossed nicols show an acute bisectrix with the plane of the optic axes at right angles to the fibrous structure. The mineral is bastite, and in all probability has been produced by the alteration of enstatite. " Under the microscope the composition of the rock is seen to vary greatly. Sometimes it is composed almost wholly of a network of serpentine containing a few grains of unal- tered olivine, bastite, and much iron ore. In other cases the serpentine is a subordinate constituent, and olivine forms the chief mass, in which are imbedded enstatite, for the most part changed to bastite, and also very rarely a colorless mineral, with prismatic and pinacoidal cleavage. It appears to belong to the pyroxene group, but with the few sec- tions present its optical relations could not be determined. It is evident that the serpentine of Qara-dagh is derived from an olivine enstatite rock. " In the Kemar Valley, a short distance east of where it opens into the Trojan Plain, loose blocks of serpentine containing numerous very bright silvery crystals of bastite have been observed. In the thin section, besides serpentine, olivine, enstatite, bastite, and irregular dark grains, there occur numerous small black crystals whose square rhombic and hexagonal sections indicate that they may belong either to spinel or magnetite ; but as they, are not translucent, they are most likely magnetite. " Further up the valley the serpentine is indistinctly porphyritic, and occurs inti- mately associated with schists and crystalline limestone, through which it appears to pene- trate in the form of irregular dikes. Its specific gravity is 2.593. The microscopical structure of these rocks is strongly contrasted with that of the serpentine from Qara- dagh. Between crossed nicols they appear rather coarsely microcrystalline, and through- out the greater portion of the section are not only uniform, but show no trace of the characteristic reticulated structure of serpentine derived from the alteration of olivine.f However, here and there a few meshes of the old net are still preserved, and there appears to be a passage from this portion into the other, in which the same structure can- not be traced. The porphyritic crystals, as in the other cases, are bastite, with considerable quantities of carbonates. According to Mr. Frank Calvert the serpentines in the vicinity of the Kernar Valley occur as distinct dikes cutting the crystalline limestones, so there can be no doubt concerning their eruptive nature, and they are in all probability derived from olivine enstatite rocks. " Near the centre of Mt. Ida the oldest rocks crop out, and among them are talcose schists, which by the addition of olivine pass into small lens-shaped masses composed * Papers of the Archaeological Institute of America, Classical Scries, i. 201, 203 ; Science, 1883, ii. 255-258. f Hussak, after studying microscopically a numher of Alpine serpentines, concluded that in the ser- pentines derived from schistose rocks the characteristic reticulated structure, chromite, and picotite are wanting. THE TERRESTRIAL PERI DOT ITES. LHERZOLITE. 145 almost exclusively of the latter mineral. According to the nomenclature of Brogger, the rock of these patches should be called olivine schist. By alteration it gives rise to ser- pent inu with the characteristic reticulated structure which ever marks the serpentine de- rived from olivine.* Occasionally the fibrous serpentine forms veins of considerable size in the adjacent rocks. The olivine schist when purest has no schistose structure. The passage from pure talc schist in which no olivine occurs to that composed almost completely of olivine, takes place sometimes within a short distance. The chief mass of the rock, how- ever, is a middle stage between the two extremes, having a distinct schistose structure and composed for the most part of olivine and talc, besides considerable quantities of pyroxene as well as other minerals not yet determined." Differing in some points from Mr. Diller, although agreeing with him in the main, it lias seemed best to add more special descriptions of the individual rocks and sections in question. It is further necessary to do this in order to point to the gradations and altera- tions which are conspicuous in them. Part appear to belong to the Iherzolite variety, while others are so far altered that it cannot be predicated what was their original com- position as a whole. A. E. 324, from Mitylene, is a greenish-black compact rock containing lighter green crystals of enstatite. The section shows a grayish-brown groundmass, holding crystals of enstatite and diallage. This groundmass is formed by a network of grayish-brown serpentine, holding olivine, eustatite, diallage, and iron ore. Much of the enstatite is altered to a grayish-brown fibrous serpentine, but some portions remain intact in part of the crystals, while other crystals are entirely unaffected. The diallage is abundant, but in small irregular grains and imperfect crystals. Part of this appears to be an augite-diallage, for it has well developed both the prismatic cleavage of augite and the orthopinacoidal cleavage of diallage, as well as traces of a clinopinacoidal cleavage. Elongated dashes of iron ore are occasionally arranged parallel to 010, forming with the well-developed cleavage parallel to 100 a rectangular grating. Part of the iron ore is secondary, occurring in grains arranged in the centre of the serpentine veins, but part appears to be the product of alteration of picotite, since the interior portion still is of a translucent reddish-brown color. From its general characters the ore is probably chromite with some magnetite. A. E. 208, from Qara-dagh, is of a similar character, but has less enstatite and diallage, and more olivine. In some places the olivine has suffered almost no alteration, while in Others the change is complete. The rock is compact, greenish-black, containing light- greenish enstatite crystals, and coated with a greenish " slickenside " of serpentine. A. E. 209, from near Mt. Daydah by the Plain of Troy, is a grayish-green rock hold- ing enstatito crystals altered into a talcose-like material (bastite) and presenting a greenish to silvery-white appearance. The section is similar to the preceding, but more highly altered, the serpentine predominating. The diallage is abundant, and in its structure closely resembles that of the meteorites, being composed of a series of granules aggregated together into larger masses, and separated by little patches of different material. A. E. 481, from the southeast part of the Chiplak, Mt. Ida, is a dark-green rock weathering brown and containing talc scales and grains, and bands of chromite. The section is grayish, and presents a schistose appearance, owing to the arrangement of its iron ore, etc. It is composed principally of a serpentine network enclosing olivine. A little enstatite and diallage were observed, also iron ore and secondary talc. * With tliis statement of Mr. Diller the present writer is unable to agree. 19 146 PERIDOTITE. A. E. 207, four miles northwest of Eanedeli, is a compact greenish-brown rock, weath- ering rusty-brown, and contains enstatite crystals. Section : greenish-gray and composed principally of secondary serpentine, with its network structure holding later altered oli- vine grains, and altered enstatite crystals containing much iron ore, and traversed and stained by ferruginous material. Many of the olivine grains between the meshes appear in common light as unchanged olivine, but in polarized light the change to serpentine is seen to be complete. Some dolomite occurs, while portions of the section present a similar structure to that given in figure 4, Plate VI. A. E. 482, from the central part of the Chiplak, Mt. Ida, is a greenish-gray schistose rock closely resembling some mica schists owing to its contained talc scales. It holds actinolite and yellowish-brown altered olivine. Section greenish-gray and composed of oliviiie, iron ore, secondary serpentine, talc, and actinolite. I am inclined to regard this rock as an altered massive rock, instead of a metamorphosed sedimentary one. A. E. 265, from the summit of Alt. Ida, is a similar schistose rock, composed of olivine and actinolite, with talc scales lying between the lamination planes. The section is composed partially of olivine, which is somewhat altered to a dirty-green serpen- tine, and partially of actinolite crystals. Iron ore and talc also occur. Mr. Diller has called this a talc schist; but I am unable to agree with him, for it appears to me to be a metamorphosed peridotite, in which the actinolite and talc are alteration- products. The foliation appears to me to have been produced during the metamorphosis, and not to be congenital. A. E. 485, from the northwest summit of Mt. Ida, is a schistose rock of a grayish- green color. The schistose structure appears to be due to alteration and to the production of talc scales. Section : composed of a network of greenish serpentine containing olivine and secondary actinolite and talc. The form of the olivine grains, and their relation to one another and to the other minerals, are sucli that I arn unable to look upon them as either of mechanical or of metamorphic origin. The actiuolite is clearly an alteration-product, and frequently separates portions of the same olivine -individual. There are two rocks numbered A. E. 483. One, coming from the central part of the Chiplak, Mt. Ida, is a compact greenish-black rock containing talc scales and weathered brown. The section is composed of serpentine, olivine, actinolite, talc, and iron ore. The alteration of the olivine has been quite extended in this. The second A E. 483 is from the northwest summit of Mt. Ida, and is a dark compact rock with little trace of a schistose structure. The section is composed chiefly of serpentine, talc, iron ore, actino- lite, and a little olivine. A. E. 473, from the summit of a ridge east of Mt. Ida, is a dark greenish and grayish rock weathering brown. It is a surface specimen. Section composed of a network of green- ish serpentine holding olivine grains, and associated with actinolite, talc, iron ore, etc. A. E. 217, from the Kemar Valley, is a compact dark grayish-green rock with green- ish and grayish porphyritically enclosed enstatite crystals. The section is composed principally of a clear pale greenish and yellowish serpentine, holding diallage, enstatite, some talc, and iron ore. The serpentine shows traces of the structure of the minerals from which it was formed. A. E. 216, from the same valley, is a similar rock, and in the hand specimen pre- sents considerable resemblance to that described from High Bridge, N. J. The section is much like that of A. E. 217. The altered enstatite and diallage have ferruginous material so arranged in their fissures as to give them a close resemblance to bronzite and hyperstheue. THE TI:I;I:I-:.STRIAL PEUIDOTITES. EULYSITE. 147 A. E. 214, from the same locality, is a similar, but more highly altered rock, which contains talcsi' material The greenish talcose schists from Mt. Ida are stated by Mr. Diiler to be associated with and to pass into the oliviue-bearing rocks above described from that locality. Ac- cepting the accuracy of his statement, it is proper to touch upon their microscopic charac- ters so far as they bear upon this relation. A. E. 484 is a greenish taleose schist containing grains and crystals of magnetite. Stained slightly with yellowish-brown ferruginous material from the decomposition of the magnetite. The section is composed principally of talc holding magnetite and patches of partly altered olivine and enstatite, traversed by a peculiar eozoon-like network of iron ore, with the longest and best marked portions approximately parallel with an optic axis. A, E. 274 is a coarser greenish-gray talc schist, composed of talc and actinolite (Diller's pyroxene) with iron ore and the remains of partially altered olivine. A. E. 270 is a beautiful green talc schist, containing crystals of actinolite and grains and crystals of iron ore. Only a few olivine grains were seen. It seems to me from the study of these rocks, coupled with similar evidence obtained from the examination of other rocks, like cumberlaudite, that these schists and schistose forms are the results of the alteration of peridotites : that is, the schists are derived from the olivine rock, and not that from the schists. This view is, of course, opposed to that of Mr. Diiler and the majority of lithologists and geologists. VARIETY. Eulysite. Tunalerff, Norway. The rock from which this variety is named was first so called and described by Axel Erdmann, in 1849, as a granular mixture of diallage, garnet, and altered olivine.* According to the later studies of H. von Mold, it contains fresh clear angular grains of olivine cut by numerous fissures and holding much magnetite in powdery grains, while the olivine is here and there altered into serpentine. A pale sea-green diallage occurs, forming large grains in the rock. This diallage shows a fine fibrous parallel structure (cleavage), which is often crumpled. This mineral often contains layers of very minute lamina, which make with the cleavage planes angles varying from 20 to as much as 60 or 70. They are arranged in parallel lines. Pale almandine-red garnet in drop-like rounded grains, and magnetite also, form constituents of the rock. Mold estimates the percentages of the minerals as olivine (fayalite) 60 per cent, diallage 35 per cent, magne- tite 3 per cent, and garnet 2 per cent.f The above description by Mold answers very well for the section in this collection purchased from Richard Fuess. The general structure and relations of the crystals indicate that the diallage and garnet, if not all of the minerals, are the results of a recrystallization of the rock materials ; i. e. it appears to be a rock whose structure has been produced by alteration and secondary crystallization, with but little if any of the original structure and minerals remaining. Kettikfjdll, Sweden. According to Tb'rnebohm, this rock is a fine granular one, greenish on the fresh fracture, ami \\vathering yellowish. Microscopically it is composed of irregular olivine Ncues Jalir. Min, 1819, pp. 837, 838. f Njt Mag., 1877, xxiii. 119. 148 PERIDOT1TE. grains, colorless pyroxene (diopside), colorless mica, and chromite. The olivine is fresh, and with the pyroxene is almost free from inclusions. The chromite is brownish on the edges, and is often surrounded or accompanied by the mica.* This rock is said to be associated with schists, and to be a concordant part of them. Varallo, Sesia Valley. Prof. A. Stelzner described a fine-grained greenish-black rock from Varallo, in Sesia Valley, as composed of olivine, hornblende, and bronzite in nearly equal amounts. Green grains were observed which were isotropic and regarded as probably chlorospinel. f Lepce, Austria. A blackish fine-grained olivine mass with light greenish-gray foliated diallage having a metallic lustre. The section is composed of predominating somewhat serpentinized olivine, whose fissures are filled with a black powder ; as well as a light reddish-colored diallage, which is fibrous and shows a feeble dichroisra between light red and light green4 Fonianapass, Locris, Greece. According to Becke the rock from this locality is a light-colored fresh olivinfels, holding porphyritic crystals of diallage. In the thin section it is seen to contain the following minerals : olivine in irregular colorless fresh grains, traversed by numerous irregular fissures ; serpentine in thin plates along these fissures ; diallage, very fresh, and traversed by cleavage planes, but sometimes this mineral is changed to a rhombic fibrous alteration-product ; and picotite, in little reddish-brown, translucent quadratic or hexagonal sections. A somewhat similar rock comes from Pyrgos, at the foot of Hymettus, in Attica. This has a black and green spotted groundmass holding large crystals of enstatite which are much altered (bastite). In the section the rock shows the ordinary network of serpentine, to which the olivine has been entirely changed. Picotite and magnetite occur. Mohsdorf, Saxony. This rock, Dathe states, contains as its most prominent mineral diallage. Sometimes along the fissures are alteration-products of calcic carbonate and iron. The olivine which is held by the diallage is generally altered to serpentine, which is filled with a powder of iron ore. Some garnet occurs. || Gillsberg, Saxony. According to Dathe, this is a dark green rock composed of dark brown to black elongated crystals, which in the thin section are dichroic from light brown to dark brown, * Geol. Foren. Forh., 1877, iii. 250; Neues Jahr. Min., 1880, ii. 197. f Zeit. Deut. geol. Gesell., 1876, xxviii. 623-625. t C. v. John, Jahr. Geol. Reichs., 1SSO, xxx. 447. Min. MiUh., 1878 (1), i. 475-477. || Neues Jahr. Min., 1876, pp. 233. THE TERRESTRIAL PERIDOTITES. PICRITE. 149 and have the cleavage of hornblende, garnet, olivine altered to serpentine in part, biotite strongly dichroic and containing little opaque needles, diallage, and iron ore.* A similar serpentine was described by Bathe from Crossen, near Mittweida, iu Saxony ; but it appears to be a somewhat more altered rock (I. c., p. 245). VARIETY. Picrite. Austria. Picrite, according to Tscherrnak, when in a fresh or little changed state, has a dark green color, and varies from a finely crystalline to a plainly crystalline character. That from Sohle has a blackish groundmass containing a large number of olivine crystals. Microscopically the groundmass holds granular feldspar, grains of magnetite, scales of black mica, and little hornblende crystals. The Freiberg and Gumbelberg picrite shows a dark groundmass holding olivine crystals traversed by numerous fissures filled by a serpentinous mineral ; also blackish- green grains of diallage. The groundmass is similar to that of the Sohle picrite : granu- lar feldspar, biotite scales, magnetite grains, and a few hornblende crystals, with here and there thin strings of serpentine. The picrite from ScMnau has a blackish-green groundmass holding olivine and dark- green mica. The mica forms aggregations of scales. Much serpentine also occurs in the rock. The groundmass consists of a granular feldspathic mass, grains and octahedrons of magnetite, blackish-green augite crystals, rarely some needles of apatite, also calcite grains, and some serpentine. An altered picrite from SoMe is a dark greenish-gray rock flecked with pistacite green spots. It contains altered diallage and olivine crystals, hornblende prisms, dark- green mica plates, magnetite grains, and silicates like gymnite and palagonite. . Another altered picrite from Bystryc, has a clear gray very fine-grained groundmass, holding inclusions of bluish-gray to apple-green and blackish-green colors. Pseudo- morphs after diallage and olivine occur, while the rock further contains magnetite and fine fissures filled with calcite. The above picrites are stated to be eruptive in the Cretaceous. Steierdorf, Banat. A blackish rock resembling basalt, and containing porphyritically enclosed olivine and quartz. It is somewhat porous, and holds calcite amygdules. The section shows that the principal minerals are olivine, augite, and hornblende. Calcite occurs as an alteration- product, and quartz as an inclusion, while an isotropic base was seen. The olivine is in large, well-defined crystals, and in smaller rounded forms. It is for the most part fresh, but it shows here and there along its edges and the borders of its fissures an alteration to a dark brown radiated fibrous aggregate. The olivine contains inclusions of glass, augite, hornblende, and picotite. The latter is in large brown isotropic sharply defined octahe- drons. The augite is of a light-reddish color, and the crystals are fresh with a feeble pleochroism. It contains inclusions of glass and picotite. The hornblende is of a dark brown color, with strong pleochroism, and contains glass particles. The hornblende is Neues Jalir. Min., 1876, pp. 241, 245. 150 PERIDOTITE. often associated with the augite. The quartz is in water-clear, beautifully polarizing fis- sured grains containing fluid and glass inclusions, as well as apatite needles.* Inclicolm Island, Scotland. An apparent intrusive mass is described by Dr. A. Geikie as composed of a serpenti- iious base holding honey-yellow grains of olivine, dark lustrous augites, and a few plates of brown biotite. In the section the olivine is in a great measure undecomposed, though presenting the usual exterior band and transverse threads of serpentine. The augite is of a pale yellow color, and in large and well-defined prisms, often enclosing olivine. A little milky plagioclase full of fissures and decomposition products was observed. Long scales of rich brown biotite occur here and there ; also a few plates and grains of probable titaniferous iron. One of the most conspicuous constituents is a rich emerald-green to grass-green decomposition product, filling up the interstices and running in veins and irregular streaks or tufts through the rock. Other pale or colorless aggregates, which are sometimes distinctly fibrous, also occur. These various decomposition products some- times show the polarization of serpentine, and sometimes that of chlorite. Some zeolitic fibrous tufts were seen.f Herborn, Nassau. The section purchased from Eichard Fuess is composed of pale brownish-yellow augite and clear fissured olivine surrounded and held by the secondary serpeutinous products. The augite in places is changed to a pleochroic green fibrous mineral, whose extinction, being parallel to the nicol diagonal, presents a strong contrast in polarized light to the mono- clinic augite. The augite holds numerous rounded grains of olivine, the same as enstatite commonly does in other rocks. The olivine is in rounded fissured forms, surrounded and traversed by the plexus of alteration material. Part of the latter is dichroic, varying from a green to brownish-yellow, and from its relations to the secondary brownish-yellow biotite it is regarded as a transition stage in the formation of the biotite. It is in irregular fibrous forms, the fibres being crumpled and aggregated together. In other portions some whitish fibrous material occurs, which affects polarized light in the same manner as part of the ac- tinolite does in the cunibcrlandite. However, the chief portion of the alteration material is serpentine. The olivine is in part very clear, and in part changed to a pale-yellowish serpentine filled with globulites and margarites of iron ore. They are seen in the serpen- tine veins ramifying through the olivine, and projecting like pseudopodia from the sur- rounding material into the partially or entirely altered olivine. The ore also forms black grains and crystals (some of which are octahedrons) in the olivine, and in the network of alteration material. It frequently forms black bands, rows of grains, or fine powder, along the fissures or centres and sides of the serpentine veins. The biotite is in irregular yellowish-brown scales and grains, some of which are surrounded by the black ore grains. It is strongly dichroic, and shows oftentimes a wavy, fibrous polar- ization. (Plate VIII. figure 6.) Ellc/olh, Austria. This rock is described by Dr. H. v. Mb'hl as having a black to blackish-green serpen- tinous groundmass holding many mica and hornblende particles. The section is in part a very fine tufted serpentine, and in part a scaly fibrous one, of * E. Hussak, Verhandl. Gcol. Rciolis., 1881, pp. 258-262. t Trans. Roy. Soc. Ediu., 18/9, xsix. 506-508. THE TERRESTRIAL PERIDOTITES. PICRITE. 151 all possible colors from a pale apple-green to a brilliant grass-green, bright ochre-yellow, siskin-green, and reddish-brown, one color running into the others. Further, there occur ivninants of the olivine grains having a light or ochre-yellow tinge, and also magnetite and gothite. The olivine remnants when untouched by alteration are colorless, very pellucid, beautifully polarizing, but extraordinarily rich in fissures, whose edges are cloudy with minute magnetite grains. Some show a light blue color, owing to exceedingly minute powder-like grains. Vapor, glass, and fluid cavities, as well as spinel inclusions, occur sparingly. The serpentine mass includes fiery reddish-brown mica ; very light grayish-brown, finely fibrous, or step-like, rough, feebly dichroic enstatite ; a little clear light-brown, fir lily dichroic augite, traversed by irregular fissures; and strongly dichroic fissured horn- blende, varying from clear ochre-yellow to a deep blackish-brown. A little apatite and plagioclase were also observed. This is a cretaceous or tertiary eruptive rock.* Pen-y-carnisiog, Anglesey. According to Bonney this rock in the section is seen to be composed of augite, horn- blende, actinolite, magnetite, opacite, serpentinous material, etc. Augite occurs in colorless grains and crystals, some of which show a characteristic cleavage. The hornblende, including actinolito, is in (1st) innumerable small acicular or blade-like crystals, in irregular tufted groups, which are pale greenish or colorless, and feebly, if at all, dichroic ; (2d) small crystals often exhibiting characteristic cleavages and even crystallographic planes, green-colored and strongly dichroic ; and large brown crys- tals, supposed to be pseudomorphs after augite. These minerals occur in a serpentinous or chloritic grouudmass containing no unchanged olivines, but pseudomorphs after that mineral were thought to be observed. Some talc (?) was seen, as well as other micaceous secondary products.^ Later Professor Bonney found a number of boulders of this rock on the western coast of Anglesey. In general these were similar to the one just described, although in one some decomposed feldspar and some diallage were observed. A little apatite, mica, etc. were seen in some of the sections.J Near the River Dill (" Dillgcgcnd"}, Nassau. This rock in the fresh condition has a blackish-green color, and contains copper-col- ored mica, green chromdiopside, hypersthene, picotite, and magnetite. The oliviue is in water-clear to pale yellowish-green grains, traversed by fissures along which occurs a fibrous greenish or yellowish-green serpentine containing mag- netite grains, etc. The chromdiopside appears as a rule in irregvdar leek-green grains showing cleavage, and is sometimes altered to a leek or smaragdite-green serpentinous aggregate. The hypersthene is pale-brownish, and shows an evident brachypinicoidal cleavage. It contains the usual violet-brown lamina?, and olivine grains. The mica shows a reddish-brown color darker than the hypersthene, is dichroic, and H"ccimcus from this locality, one in octahedral crystals, the other massive. 180 PERIDOTITE. Troup Co., Georgia ; Dudleyville, Alabama ; California ; near New Idria, Monterey Co., California ; Ural Mountains ; and Euboea, Greece. Another specimen from California had a yellowish and greenish-brown color, while one from Sweden, when very thin, was of a deep-brown coffee-color. The seven following chromites were sent by Dr. Dana. Those from Lancaster Co., Pennsylvania ; Cecil Co., Maryland ; Franklin, North Carolina ; and Bisersk, Ural Mountains, have a yellowish-brown color. Two specimens from Texas, Pennsylvania, require to be very thin to become translucent, and are of a yellowish-brown to reddish-brown color. One from Jamaica, West Indies, is greenish-yellow in its apparently freshest state, but in the partially changed condition it is reddish-brown. A chromite obtained from Mr. Kerr, Commissioner from North Carolina at the New England Fair of 1883, in thin splinters is of a clear coffee-brown color with a greenish tinge. Its fracture is smooth, and presents a surface closely resembling a hardened black gum or pitch for example, albertite and has a lustre varying from resinous to vitreous. This was chipped from a large block sent to that exhibition. Most of the chromites examined have a pitchy or resinous look, with a velvet-black color closely resembling solid coal tar ; but some are dull. While it may be said that in general more or less translucency exists in the powder of chromite, this apparently resides only in certain portions of the mineral, which is not translucent as a whole. So far as the writer is aware, no tests have been made to compare the relative hardness of picotite and chromite, but the former has been assumed to have that of the normal spinel. In the same way the color of the streak of picotite does not appear to be known for itself ; while that of chromite would seem to be due to its translucency. In specific gravity the two minerals bear close relations. Chromite varies in its specific gravity as follows: 4.031, 4.0639, 4.11, 4.115, 4.1647, 4.319, 4.422, 4.439, 4.49, 4.50, 4.534, 4.56, 4.566, and 4.568; while the only deter- mination of picotite found, places it at 4.08. Both minerals have the same crystallographic form, the same color to their thin sections, and the same color and lustre in the massive state. The term cofcc-brown as used in this text and in the writings of others partakes of the same variability in shade that the infusion of coffee itself does, running from a yellowish or greenish-brown through a reddish-brown to a deep dirty- or muddy-brown. The depth of color, even in the same specimen, AND PICOTITE. 181 appears to be due in part to the thickness, and in part to alteration. For example, in some the yellowish-brown and reddish-brown shades are mingled in such a manner that it is evident that the latter shade is due to change in the state of the iron, and marks a stage in the progression towards opacity. In other cases the two tints are so related that the shade is seen to be due to the wedge-shaped form of the fragment examined. The translucency is better observed in the powder than in the thin sec- tion, il' the mineral tends to be at all opaque, since thinner edges are obtained by the process of fracture. The writer has found the quickest and simplest w;i v to prepare the powder for microscopic examination, to place a minute fragment, less than a pin's head in size, on a glass slide,* and then crush it on this slide under a clean knife-blade. The scattering of the powder can be pre- vented by placing a finger over the blade at the point under which the grain lies. In this way, by using a small blade, the finger projects over both sides and serves as a cushion to prevent the broken particles from flying off, gives a more uniform pressure, and saves the production of so much fine dust as to obscure our observations. Thus the powder can be directly examined on the slide on which it was crushed. It does not appear practicable at the present time to enter upon any satisfactory discussion of the chemical relations existing between picotite and chromite ; yet, as a contribution towards that desired end, a list of analyses of the two minerals has been arranged in order of the relative percentage of chromic oxide, and it will appear in the list of tables as Table I. One of the difficulties in the way of a satisfactory determination of the relations of chromite and picotite is the absence of analyses made from material care- fully studied microscopically, as well as a like absence of analyses made from material of intermediate grades between the typical picotite and the typical chromite. For it will not escape the observer's attention that the analyses naturally group about these two poles, since typical specimens arc selected for analysis. Another difficulty is the fact that only five analyses of picotite and one of chrompicotite are known, out of the one hundred and twenty analyses here collected. Hence it is that the series of analyses is far from being so continuous as it would probably be found to be if more attention had been paid to the question of the relations of these two minerals. The percentage of chromic oxide begins as low as 4.74 per cent in one chromite, and in the picotites does not rise higher than 8 per cent, while the * Any window-glass, if cut of proper size for tlie stage of the microscope, will do. 182 PERIDOTITE. chromites next in order contain 9.80, 16.80, three between 17 and 18 per cent, then 21.16 and 31.20. The chrompicotite, however, contains 56.54 per cent of chromic oxide. The highest percentage is 77-00, in a doubtful analysis by C. H. Pfaff ; while the next lower has 64.17 per cent. The highest percentages of alumina in the chromites are 30.17, 27.83, and 24.71, but in general it diminishes in amount as the chromium increases. In picotite the alumina is high, being 50.34, 52.47, 53.93, 55.34, and 56.00 per cent, and in this occurs the only real chemical difference between pico- tite and chromite. In the chrompicotite the alumina is 12.13. The percent- age of magnesia is about the same in both the chromites and picotites, and does not bear any observable proportion, to any other element. The highest percentages are, in picotite 23.59, and in chromite 28.71 and 25.40. The oxides of iron irregularly increase as the chromic oxide does, rising as high as 45.22, 48.46, and 62.02, while the lowest percentages are 2.30, 5.60, and 9.00; but picotite contains the following: 22.27, 21.42, 15.25, 24.60, and 24.90, and the chrompicotite 18.01. The silica and lime diminish irregularly as the chromic oxide increases. The highest percentages of silica are 26.01, 26.70, and 14.211; and of lime 24.36, 13.26, and 10.55. The minor and rare elements are the oxides of nickel, manganese, and carbon. The more general relations are perhaps best shown in the tables inserted here in the text. TABLE I. No. of Analyses. 23. 25. 27. 28. 17. Limits of Cr 2 3 percentages. 4.74-38.1',*. 39.O5-44.91. 45.00-52.12. sa.ia-sr.ao. 5S.OO-77.00. Percentage Lim- its of Elements. t o K S o J I _^ | 1 | i d 1 I Si I : I ! s - i 1 d 3 J ri A j 8 ? 9 4 c o Z ~ ~ ^ s i i * S Of r I 1 MffO 1 J. 5 in 17 8 14 7 11 3 2 4 5 8 2 1 I 1 5 5 5 1 11 10 5 o 2 9 10 8 1 ii n 15 2 in n 3 6 1 3 12 29 5 >\ 5 13 6 4 3 19 6 4 1 3 14 10 8 1 13 3 3 G 3 y 8 ALO, 1 3 5 7 r 8 11 Fc 2 O a FeO SiO 2 11 12 5 5 'i' U _ CaO 17 8 21 3 Table I. has placed in its upper line the number of analyses in each set ; in the second line, the percentage limits of the chromic oxide in these analyses ; while on the third line is placed the percentage limits of the magnesium, aluminum, ferric, ferrous, silicon, and calcium oxides. Below are given the number of analyses found in the above limits. Thus, for instance, CHROMITE AND PICOTITE. 183 in looking at the table it can be seen that in the first 23 analyses the limits of Cr 2 3 are 4.74 and 38.12; while in these 23 analyses, there are to be found of analyses of Mg 0, one having no Mg ; four having less than 10 per cent; fourteen carrying between 10 and 20 per cent; four carrying between 20 and 30 per cent ; and none having any higher percentage. But in these same 23 analyses we see that there are five (picotites) which carry between 50 and GO per cent of A1 2 O 8 . TABLE II. Percentage I.innt -. t a o S5 3 I : i i 3 i i 8 2 si |i Cr.O, 7 4 i IB 3f> 43 13 i Fe'o!.' 81 10 8 fi 10 1 FcO IS 4 98 49 18 5 a ALO, ... . 8 53 36 19, 1 5 4 MjrO 15 49 55 8 SiOj 17 9, ii. 329-361. J ZciU Gessam. Katur. Berlin, 1879 (3), iv. 1-18. 192 PERIDOT1TE. peridotites, especially those containing pyroxene minerals ; but the present writer's studies would indicate to hirn that the most common source that yields by alteration our soapstone or steatite rocks, is to be sought in our gabbros and coarser crystalline diabases (diorites). The purer talcose rocks would appear to come from the former source (the peridotites), the more impure ones from the latter (the basalts). From the evidence in the preceding pages, it is probable that some actino- litic and other schists result from the alteration of the peridotites, although in general the amphibole schists appear to belong to other groups. The formation of impure dolomites from peridotites would seem to have been clearly shown in the preceding pages, but how far this will account for the common association of magnesian limestones with serpentine, is a problem for the future. One thing, however, appears clear, that such limestones are produced on a small scale, and sometimes on a more extended one in connec- tion with the general alteration of peridotites into serpentine. It is not the part or intention of the writer to explain the modes of change in these rocks. It is rather his part to give the facts observed, and for the mineral chemist to engage in the work of explanation, unless he can impeach the facts presented. SECTION X. PcridoUte. Its Classification. As previously stated (ante, pp. 84, 85), all rocks of this class are here grouped under one species or type peridotite ; while for the modifications produced by the variation in mineral composition, varietal names are em- ployed, in deference to the views of those who make species out of every mineral variation in rocks. Since, so far as practicable, these variety names are the same as the specific names of other lithologists, and have the same general limits, no difficulty will arise in their use, whether the person em- ploying them looks upon each division as a specific or a varietal term. In accordance with the methods of this work, peridotite is defined as including all meteoric and terrestrial rocks of every age, which are composed essentially of olivine, with or without pyroxene minerals, and iron ores including picotite. It has not been customary to base any varietal distinction on the iron ores, or hardly to look upon them as essential, although they are universally ITS CLASSIFICATION. 193 present, or nearly so. The varietal distinctions (specific, of other lithologists) are founded on the pyroxene minerals and on the alteration-products. Thus dm, ilc is the terra given to the form of peridotite which is essentially com- posed of olivine ; saronite to that composed of olivine and enstatite ; Ihcrzolite to that composed of olivine, enstatite, and diallage ; hichncrile to that com- posed of olivine, enstatite, and augite : cnlysitc to that composed of olivine and diallage ; and /i/r/-/fe to that composed of olivine and augite. Under these varieties are classed all the forms produced by alteration, so far as they may retain sufficient original characters for their identification ; when they do not, then they are placed under a variety name belonging to the produced form. Thus, serpentine is given as the variety name for all the altered peridotites in which serpentine forms the essential constituent; talc schid to all in which talc holds a similar part ; and in the same way any variety produced by alteration can be designated by its common name when its derivation is known. It is, however, expected that future studies will lead to the discovery of every mineralogical combination that can be formed by the principal silicate constituents of peridotite. These combinations, so far as now known grade into one another, and it is to be expected that all other dis- covered ones will do the same. Hence, if the ordinary methods of nomen- clature should be followed, the number of species or varieties of peridotite would be great and their separation difficult. However, the present writer, as he has previously stated, does not place any stress upon the subdivisions now made on a mineralogical basis in peridotite, but adopts them as a con- venience only in the present state of lithological science ; and they can readily be replaced by the general employment of the specific name perulolili'. The limburgite of Rosenbusch has not been placed here with the peridotites, for its microscopic structure is like that of some of the porphyritic glassy basalts, and differs much from the peridotites. While its percentage of silica is like that of this species, its contents of alumina and lime ally it to a more acidic group; although it is not improbable that it belongs to the picrite variety. Except in its abundant olivine, limburgite microscopically closely approaches some of the andesites ; but, taking its characters as a whole, the majority of them appear to be basaltic, and with that group it will here be classed until further evidence can be procured. The fragmental states of the peridotites arc indicated for the unaltered 25 194 PEEIDOTITE. and altered forms by the respective varietal terms, tufa and porodite, or, if desirable, their adjective forms, tvfaccous and poroditic. Below is given a table showing the classification of all the rocks more basic than the basalts, so far as now known, but it admits of the ready addi- tion of other varietal names, and even of specific ones, if future studies shall indicate such divisions. The three designated classes of varieties are of course not entirely distinct, since in alteration a mineralogical change enters, and that change or alteration is the basis of the two divisions of the fragmental forms, while these may partake of the mineral characters of the mineralogi- cal varieties, and belong to them. Table showing the Classification of the Rock Species preceding the Basalts. Species. Mineralogical varieties. Alteration varieties. Fragmental vari- eties. Siderolite. Pallasite. Pallasite Cumberlandite. Actinolite Schist. Dunite. Peridotite. Saxonice. Lherzolite. Buchnerite. Eulysite. Picrite. Serpentine. Talc Schist. Actinolite Schist. Tufa. Porodite. This seeming confusion or crossing of names is due to the present state of lithology, and the necessity of bringing the nomenclature into accordance with the general usage and prejudices of lithologists, since an abrupt departure from their nomenclature would only repel, and the inconsistencies can later be remedied by the dropping of all varietal names which the advance of the science shall render superfluous, as the writer now believes many of them to be. Thus, for instance, it is here considered that in peridotite, the terms peridotite, serpentine, and talc and actinolite schist, with the adjectives tvfaccous and poroditic, will express every essential form of these rocks now known, and by their use alone a proper conception of their relations would be ad- vanced. CHAPTER IV. THE BASALTS. SECTION I. The Meteoric Basalts. VARIETY. Basalt. Slaimcrn, Moravia. TSCHERMAK has described the Stannern meteorite as a gramilar rock, showing an evident fragmental structure. According to him, it is not a homogeneous crystalline rock, but oue composed of rock fragments of three different kinds : coarse-grained frag- ments, radiated finer-grained fragments, and compact fragments. The coarser-grained fragments are chiefly composed of anorthite laminae and augite columns united together. Some of the anorthite crystals show very fine twinning, but most have broad twin laminae which are sometimes bent. Besides the colorless anorthite, and the brown to blackish augite, Tschermak observed a colorless isotropic mineral, which i* probably the same as the mineral he had described as an isotropic labradorite (maske- lynite) from the Shergotty meteorite. Minute grains of chromite, iron, and pyrrhotite occur inclosed between the other minerals ; and black forms were seen in the augite. The fragments, of an evidently radiated texture, are composed of anorthite laminae interspersed with augite needles. Black grains occur in these fragments. The compact fragments formed a gray mass, which in several points showed a radiated fibrous structure, and which contained the before-mentioned black grains. The groundmass which unites these fragments is composed of anorthite and augite grains, and black particles.* Tschermak later stated that this meteorite was closely like that from Juvenas, but finer- grained ; but it did not contain either the unknown silicate or pyrrhotite found in thatf The specimens of this rock in the Harvard College Mineral Cabinet, resemble in structure, on macroscopic examination, some diabases, but are of a much finer grain ; the general crystalline arrangement is the same. Constantinople, Turkey. The Constantinople meteorite was found by Tschermak to be an ash-gray, nearly compact rock, composed of compact small fragments and fine radiating masses. It was seen under the microscope to be composed of anorthite, pryoxene, pyrrhotite, and cliromite. Its microscopic structure agrees with the Stannern meteorite, as also does its chemical composition.^ * Min. Mitth., 1872, pp. 83-85. f Die mikros. Bescli. dcr Meteoriten, 1883, i. 7. J Min. Mitth., 1872, pp. 85-87.' 196 BASALT. Jbnsac, France. The Jonzac meteorite is stated by Tschermak to have a fragments! structure, and under the microscope is seen to be composed of lamella} of anorthite and columns of augite. The former has distinct bounding lines, while those of the augite are indistinct. Lying between these crystals are small grains of the same minerals, filling the interspaces. The anorthite is often cloudy from minute brown glass inclusions, and black grains arran- ged parallel to the length of the crystal. The augite when clear has a greenish-brown color, but it is often traversed by fissures, and rich in violet-blue, and brown, dust-like particles, chromite and pyrrhotite, possibly. The meteorite further contains pyrrhotite, chromite, and iron.* Petersburg, Lincoln Co., Tennessee. The Petersburg meteorite is, according to Professor Shepard, of an " ash-gray color, with a slight intermixture of pearl-gray, for the basis of the stone." Porphyritically inclosed in this groundmass are crystals and grains, which, from Shepard's and Smith's descrip- tions, appear to be augite, plagioclase, and olivine. Some chromite and a garnet were reported. f Tschermak states that it is composed of anorthite, augite, and a yellowish silicate like olivine.J The specimen in the Harvard College Cabinet macroscopically closely resembles the Stannern meteorite. Frankfort, Franklin Co., Alabama. The Erankfort meteoric stone, according to Professor Brush, presented a gray ground- mass with a pseudo-porphyritic structure, having black, green, white, and dark-gray spots on it. Professor Brush determined the minerals as follows : the black one as chromite ; the white as anorthite or chladnite (it is more probably feldspar than enstatite) ; the green and gray as olivine (probably some augite also) ; and, in addition, a little nickel- iferous iron, and pyrrhotite (troilite). This rock seems to be a basalt, to which its chemical analysis refers it. VARIETY. Gabbro. LuotolaJcs, Finland, Rusida. The meteorite from Luotolaks was found by Professor F. J. Wiik to be composed of metallic iron; colorless anorthite; grayish-violet augite, inclosing long black microlites ; and olivine, with little irregular cavities.|| He refers this meteorite to the basic eruptives. Tschermak describes it as a tufaceous mass, which, in an earthy, friable, gray ground- mass, holds splinters and grains of greenish, whitish, and dark color, as well as basaltic (eucritic) fragments. He looks upon it as a volcanic ash. It contains, according to him, anorthite holding little rounded glass inclusions ; augite in brownish grains, with black needle-formed inclusions ; bronzite in very pale, greenish splinters, almost free from inclusions ; olivine, chromite, pyrrhotite, and iron. ^[ * Min. Mitth., 1874, pp. 163, 109. f Am. Jour. Sci., 1857 (2), xxiv. 134-137; Safford's Geol. Reconn. of Term., 1856, pp. 125-127; Geol. of Tenn., 1S69, pp. 520, 521. | Min. Mitth., 1874, p. 170. Am. Jour. Sci., 1869 (2), xlviii. 240-244. || Neues Jahr. Min., 1883, i. 384; Ofvorsigt Pinska Vet. Soc. Forh., 1882, xxiv. 63, 64. ^f Die mikros. Beseh. der Meteoriteii, 1883, i. 7, 8. THE METEORIC BASALTS. GABBEO. 197 Massing, Bavaria. The Massing meteorite is said by Professor C. W. Giimbel to be of a grayish-white color in the interior, and to contain olivine in yellowish-green to clear-green, round, and irregular grains, which sometimes show parallel fissuring. He refers to feldspar a white, glassy, transparent, or dusty, cloudy, strongly-fissured, rarely parallel-striped, evidently cleavable mineral. A wine-yellow to grayish-green, or pale, reddish-brown glassy mineral is regarded as belonging to the augite group. It is not dichroic, and is sometimes in long fibrous forms, and filled with numerous little bubbles. Besides these, chromite, pyrrhotite, and iron were found. All these are cemented by a fine, dust-like, granular, gray groundtnass.* Tschermak states that the Massing meteorite is similar in character to that from Luotolaks, and contains anorthite, brownish, yellowish, and greenish-gray augite, bronzite, chromite, pyrrhotite, and greenish splinters of olivine.f Jitvcnas, ArdecJie, Frame. According to Eammelsberg, this meteorite is composed of anorthite, augite, chromite, pyrrhotite, and possibly a little apatite, and titanite. It is similar to the Stannern form, but coarser \ Hose states that the nickeliferous iron is in a very minute quantity. The specimen in the Harvard College Cabinet looks macroscopically more like a gabbro than the Stannern form, and it has a coarser texture. This meteorite is figured by Fouque and LeVy, as being composed of anorthite, enstatite, augite, and magnetite,|| and having a structure like some norites. Tschermak states that it shows a crystalline to tufaceous structure under the micro- scope, and is evidently of a brecciated character. The anorthite in it is well-crystallized, part being water-clear, and part cloudy and white, owing to rounded and fine needle-formed glass and other inclusions arranged parallel to the bounding planes. The crystals often show in polarized light a compli- cated twinning. Some of the inclusions hold bubbles and black grains. Earely gas- pores were seen. The augite is brownish-black, owing to numerous black, and rarely brown, needle- shaped and rounded inclusions. The brownish rounded inclusions are regarded as glass. Some irregular grains of a pale-brown color are referred to diallage. A pale-brownish silicate, sometimes having a fine lamellar structure was observed. Small amounts of pyrrhotite and nickeliferous iron were also found by Tschermak.lT Sliergotty, India. A description of the microscopic characters of the Shergotty meteorite was given by Professor Tschermak in 1872. The stone is granular, with the grains nearly of the same size, and on the fractured surface it has a yellowish-gray color. In the thin section five different minerals were recognized : 1, a brownish cleavable mineral similar to augite ; 2, a glass-clear isotropic mineral ; 3, a yellowish, anisotropic mineral, very rare ; 4, an opaque black mineral magnetite ; 5, an opaque metallic yellow mineral, extremely rare. Sitz. Miinchcn Akad., 1878, viii. 32-40. f Die mikros. Besch. der Meteoriten, 1883, i. 8. J Ann. I'hvsik flicmio, 1848, Ixxiii. 5S5-590 ; 1851, Ixxxiii. 591-593. AMi. Berlin. Akad. 1863, pp. 120- 134. || Min. Microfj., 1879, plate LV. figure 1. f Die mikros. Besch. der Meteoriteu, 1883, i. 6, 7; Min. Mitth., 1874, pp. 169, 170. 198 BASALT. Of these the first formed the principal portion of the stone. It is traversed by number- less fine fissures parallel to the cleavage. It is of a grayish-brown color, anisotropic, and shows only feeble pleochroisin. In cleavage and optical characters it is similar to diopside. It is quite commonly twinned. While the mineral is regarded as augitic, Tschermak thinks, from its chemical composition, that it is different from any terrestrial compound. The second mineral possesses conchoidal fracture, and is inclosed in and subordinate to the augitic mineral. Its form is that of a distorted cube. The hardness is a little less than that of orthoclase, while its chemical composition is similar to that of labradorite. Tschermak proposed for it the name maskelynite. The third mineral is intergrown witli the first, is traversed by parallel fissures, and is orthorhombic in crystallization. It is referred to bronzite (eustatite). The fourth mineral lies between the other minerals or is inclosed in the maskelynite. It is pitch-black, semi-metallic, with a conchoidal fracture, black streak, and is strongly magnetic. This mineral is regarded as magnetite. The fifth mineral is referred to pyrrhotite. The section as figured by Tschermak resembles some of the gabbros.* Later, Tschermak speaks of the brownish mineral as augite, and of the inaskelynite as a glassy state of plagioclase.f PaivlowJca, Saratow, Russia. This meteorite has been described by Mr. Th. Tschernyschow, as composed of a brittle ash-gray groundmass, formed by a crystalline-granular mixture of feldspar, ensta- tite, and diallage, holding porphyritic grains of these minerals and olivine. The feldspar shows polysynthetic twinning, and is referred to anorthite. It is in irregular and ledge- formed masses. The diallage is either colorless or brownish-gray, with cleavage planes, and an absence of dichroism. The enstatite shows a fine parallel cleavage striation, and holds chromite (?) in black grains arranged parallel to the cleavage lines. Sometimes the feldspar predominates, and at others the pyroxenes ; and of the latter, sometimes the enstatite and sometimes the diallage is most abundant. The olivine occurs in clear-green grains. Besides the above minerals, there were seen also nickeliferous iron, pyrrhotite, and chromite, in grains and crystals. It also contains the cloudy-gray friction-product of Tschermak, but which the present writer regards as a base. $ This meteorite is placed, from the above description, with the basaltic meteorites, although the entire correctness of the microscopic diagnosis is perhaps questionable. Le Teilleul, Manche, France. This meteorite, according to Daubree, is composed of plagioclase (anorthite), enstatite, diallage, olivine, iron, pyrrhotite, and chromite. The feldspar is colorless, twinned, and presents similar inclusions to those found in the feldspar of gabbro. On chemical tests the feldspar is referred to anorthite. The enstatite shows two cleavages, is of a pale-greenish color, and contains opaque inclusions. The diallage is of a darker color than the enstatite, and contains inclusions of oxide of iron or troilite, as well as other forms similar to those common in diallage, and arranged parallel to one another. The oliviue is colorless. * Sitz. Wicn. Akml., 1S72, Ixv. (1), 122-135; Miu. Mitth., 1872, pp. 87-05. j- Die mikros. Besch. der Meteoriten, 1883, i. 7. j Zeit. Deut. geol. Gesells., 1883, xxxv. 100-192. Cumplea llendus, 1S79, kxxviii. 544-547; Neues Jahr. Mia., 1879, pp. 905, 906. THE METEORIC BASALTS. GABBRO. 199 BukopviBe, South Carolina. The meteorite which fell at Bishopville, South Carolina, March, 1843, has been regarded as an interesting and peculiar one. Professor C. U. Shepard, hi 1846,* described from it, iiinler the name of Cldadnite, a mineral which he regarded as a ter-silicate of magnesia, and as forming over two-thirds of the stone. The color is snow-white, rarely tinged with gray. Lustre pearly to vitreous, translucent, H. 6-6.5. Sp. Gr. 3.116. Fuses without diiliculty before the blowpipe to a white enamel. He further describes as apatoid, small, yellow, semi-transparent grains having a hardness of 5.5, and very rare. A third mineral, which he names iodolite, is of a pale, smalt-blue color, vitreous lustre, and brittle. Hard- ness 5.56. Fuses easily with boiling into a blebby, colorless glass. The iodolite was found only in a small quantity. Later, Shepard gave a fuller account of this stone, holding that it contained, chladnite 90 per cent, anorthite 6 per cent, nickeliferous iron 2 per cent, and 2 per cent of mag- netic pyrites, schreibersite, sulphur, iodolite, and apatoid. f The stone was next investigated by \V. Sartorius von Waltershausen. He described the principal mass as a white siliceous mineral, forming a finely crystalline mass, with here and there little points showing metallic lustre, also grains of magnetite and brown oxide of iron. The hardness of the white mineral is given as 6, and the specific gravity as 3.039. His results indicated that the siliceous portion of the meteorite Was composed of 95.011 per cent of chladnite, and 4.985 per cent of labradorite. The former he found to be monoclinic, and related to wollastonite in specific gravity, color, texture, hardness, and crystalline form. J Later, Professor J. Lawrence Smith stated that, from some of his investigations, " chladnite is likely to prove a pyroxene ; " and subsequently published a further discussion, in which he said of chladnite : " It is identical in composition with Enstatite of Kenngott." || Earlier than Smith's last paper, some investigations were made upon this meteorite by Professors Carl Rammelsberg and Gustav Hose. The former held that the yellowish-brown and bluish-gray particles (the apatoid and iodolite of Shepard) arose from the oxidation of the nickeliferous iron or the alteration of the pyrrhotite. Hose's examination showed that the chladnite fused before the blowpipe only on the the edges to a white enamel. ^[ Eammelsberg, in the continuation of bis work, further declared that no feldspar was to be found in the stone.** Through the courtesy of Mr. John Cummings and Professor A. Hyatt, the Curator of the Boston Society of Natural History, I have been permitted to make a microscopic examination of a small portion of this meteorite now deposited in the collection of that society. The portion examined is a grayish-white mass, resembling, as Shepard remarked, a grayish-white granite (albitic), with brown and black spots. Under the microscope it is seen to be composed of an entirely crystalline mass of enstatite, augite, feldspar, olivine, pyrrhotite, and iron. The structure is essentially granitic, and it appears to belong to the gabbro (norite) variety of basalt. The enstatite is clear and transparent. It shows a longitudinal cleavage parallel to the line of extinction, and in some specimens this is crossed by a cleavage at right angles. It * Am. Jour. Sci., 1846 (2), ii. 380, 381. } Ann. Chem. Pharm., 1851, hxix. 369-374. II Ibid. 1864, xxxviii. 225. 220. ** Ibid. 1870, pp. 121-123. t Ibid. 1848 (2), vi. 411-414. Am. Jour. Sci., 1855 (2), xix. 163. If Abb. Berlin. Akad. 1863, pp. 117-122. 200 BASALT. also has a cleavage which is often well marked, and divides the mineral into rhombic forms, with angles, as approximately determined by several measurements, of 73 and 107. The principal cleavage is parallel to the longer diagonal of these rhombs. It is this rhombic cleavage, probably, which has led observers to believe that chladuite crystallized in the monoclinic and triclinic systems. The enstatite is found to contain mauy glass inclusions with polyhedral outlines, the planes being presumably, as usual in such cases, the planes of the inclosing mineral. While many of these inclusions are arranged in the eustatite parallel to the cleavage planes, others are placed at every angle with those planes. The glass inclusions carry bubbles, microlites, and rounded lenticular forms. The latter are frequently at the end of the inclusion, and in some cases, show the cherry-brown color of some chromite. This mate- rial, besides forming inclusions in the glass, is in lenticular and irregular rounded grains in the enstatite itself. It sometimes extends in a series of grains across the entire eustatite mass, and at others is in isolated forms. These inclusions, microscopically, are seen to be composed of a centre of nickeliferous iron or pyrrhotite, surrounded by a band of dark material, chromite or magnetite, possibly. These ferruginous materials are in many cases surrounded by a yellowish-brown staining of iron, which sometimes extends over considerable of the mass and along the fissures. Numerous vacuum or vapor cavities were observed, which were arranged in one plane of the enstatite. The inclusions are seen to be crossed and cut by the cleavage and fissure planes of the enstatite, showing that they were of prior origin to the fissures. The feldspar stands next in abundance to the enstatite, and is in irregular masses held in its interspaces. It is water-clear, and almost invisible by common light. Much of it is seen to be plagioclastic, but the twinning bands are so exceedingly fine, and the polar- ization colors so bright, it does not, as a rule, show well this character, except with high powers, and when the mineral is near the point of extinction. The feldspars contain numerous yellowish-brown, dark, and almost colorless inclusions, which are sometimes irregularly scattered, but more commonly are arranged in bands, similar to those of the fluid inclusions in quartz. These glass inclusions are of various dimensions, and many contain a small bubble. Some microlites were also seen. In the feldspar at one end of a section, the enstatite was found in minute crystals ex- tending outward from a centre, forming stellate or rosette-like forms. The structure is like that observed in terrestrial rocks, in minerals formed from alteration or solution. This apparently might have been produced in this case, either by the rapid crystallization of enstatite material in a liquid feldspathic mass, or by secondary alteration through water- action on the rock itself. The absence of any other signs of alteration, except of the ferruginous materials, seems to negative the latter supposition. The ferruginous alteration can probably be accounted for by the absorption of moisture by this friable fissured stone since it reached the earth. The bands of inclusions were seen in several instances to extend from the feldspar through the enstatite, and in one case, to pass into another feldspar on the opposite side. This indicates that the cause of these inclusions was a general one for the rock-mass, and not limited to any one mineral. Enstatite was found in a few cases inclosed in the feldspar. The monocliuic pyroxene or augite is less abundant, and its determination less sure than is the case with the enstatite and feldspar. It is crossed by fissures in a very irreg- ular manner, but shows in some cases the approximately right-angled cleavage of augite. Its optical characters appear to be those of that mineral, but its polarization is more bril- THE METEOEIC BASALTS. GABBRO. 201 liant than terrestrial augite, and resembles oliviue. All the transparent minerals of the section are clearer, ami lighter-colored than their mundane representatives, and hence tend to show in polarized light clearer and more brilliant colors; The augite is not, however, quite so water-clear as the eustatite, but has a very i'aint tinge of yellowish-green. The 1'iTMiginous inclusions are the same in this as in the enstatite. The determination of the olivine is more doubtful, since it is seen only in small irreg- ular graius and masses, which hold the same relation to the other minerals that the olivine of terrestrial gabbros usually does to its associated minerals. From this, and the fact that it optically has the characters of oliviue, it is here assigned to that species. From the description of the mineral constituents of this meteorite, it would seem that, regarding the presence of the feldspar, Messrs. Shepard and Waltershausen were correct, while Eammelsberg was not. It shows the inability of the ablest rnineralogical chemists to draw correct conclusions regarding the mineral constituents even of an unaltered rock. The trouble appears to reside in the instrument used a defect in the method. Chladnite ought no longer to be regarded as eustatite of the purest kind, as stated in most mineralogies, but rather as a mineral aggregate of which enstatite, feldspar, and augite are the principal constituents. While these observations gave an approximate solution of the Bishopville meteorite puzzle of twenty-seven years standing, it would be well if some one having larger amounts of this meteorite could make a chemical analysis of it as a whole, and also analyze the minerals by the modern microscopic, specific-gravity, chemical method.* This stone, from the above observations, is, in its mineralogical composition, structure, bubble-bearing glass inclusions, and microlites, like a terrestrial eruptive rock, and it is presumable that it had a similar origin. There are many who hold that the terrestrial eruptives are produced by the aqueo- igneous solution of chemical precipitates from the primeval ocean or thermal springs, or from sediments buried under the ruins of the earth's crust. Would it not, then, be in order for these scientists to explain the formation of this meteorite in the same way ? Now if this body was thrown from the sun or a similar globe, by eruptive agencies, would it not then be proper for these writers to speculate how this sun commenced with a cold, inert surface, and a solid interior ; and how, later, by its being blanketed by its own detritus, it had been raised to its present intensely heated condition ? a speculation which is in entire accord with methods formerly advocated by ardent Wernerians to account for the heated condition of the earth. Since the publication of the preceding description of this meteorite, Tschermak has published independently another description. He recognized the presence of enstatite, plagioclase, and pyrrhotite.f Manegaum, India. The Manegaum meteorite was described by Maskelyne in 1863, as composed of a probable olivine and an opaque white or yellowish-white mineral The latter occurs as a flocculent network, iu round spherules, in fragments, and along the lamina? of the crystals of other minerals. Some pyrrhotite and chromite (?) were observed. J In 1870, Maskelyue determined the supposed oliviue to be enstatite, to which he * Am. Jour. Sci., 1883 (3), xxvi. 32-36, 248. f Die mikros. Besch. der Metcoriten, 1883, i. 9, 10; Sitz. "Wien. Akad., 1883, hxxviii. (1), 363-365. { Phil. Mag., 1863 (4), xxvi. 135-139. 26 202 BASALT. also referred the opaque flocculent white mineral. Minute amounts of iron were found. The analysis and composition as given are not satisfactory, and it is thought that a more extended microscopic examination would throw ' some light upon tin: subject. This, like the Shergotty meteorite, is probably closely like the gabbros in structure.* Busti, India. According to Tschermak, this is composed of crystals and fragments lying in a fine- grained, splintery groundmass, all composed of diopside, eustatite, plagioclase, uickel- iferous iron, oldhamite, and osbornite. The diopside predominates, and has a gray to violet color, and contains rounded and needle-shaped crystals arranged parallel to the fibrous cleavage. These inclusions are the cause of the violet color. The enstatite is in colorless splinters, and in gray cloudy forms replete with inclusions. These often show a polyhedral contour, and are filled with a pale-brownish glass, bear- ing bubbles. The plagioclase occurs only sparingly, and is colorless and nearly free from inclusions. The oldhamite only appears in a portion of the rock in rounded grains having a cubic cleavage ; the osboruite in octahedrons in the nickel-iron, which occurs only sparingly.! ShalJca, India. Tschermak describes this meteorite as composed of a clear-gray, somewhat friable mass, with inclusions of larger, greenish-gray, bronzite grains, and blackish chromites. Under the microscope the larger bronzites are seen to lie in a groundmass of bronzite fragments. This mineral often contains brown glass inclusions or opaque grains. The last are arranged in the fissures in the bronzite, and are referred to pyrrhotite. Some greenish-yellow grains, regarded by Eose as belonging to olivine, were placed by Tschermak under bronzite, on account of their cleavage and action in acid. J Ibbenbuhren, Westphalia. The meteorite of Ibbenbiihren consists of a grayish- white, granular mass, in which large and small grains of a light-yellowish-green mineral are unequally distributed. From the chemical analysis and physical character of this mineral, Von Eath referred it to bronzite, and to the same mineral he assigned the groundmass, regarding the entire meteorite as composed of bronzite (diallage). ' According to Tschermak, || the bronzite forms the principal portion of the stone, and occurs in irregular grains of varying size. Some thin lamime were referred to augite, and some little colorless grains filling the interspaces between the bronzite grains were looked upon as plagioclase, or possibly tridymite. The inclusions are in part reddish-brown glass, and in part opaque grains referred to chromite and iron. Greenland. On account of its interest in connection with the occurrence of metallic iron in basalts, a description of the iron-bearing basalt of Greenland is placed here in con- nection with these basaltic meteorites. * Phil. Trans., 1870, pp. 211-213. f Die mikros. Bcsch. der Mctcoriten, 1883, i. 9. J Die mikros. Besch. dcr Mctcoriten, 1883, i. 10. Monats. Berlin. Akad., 1872, pp. 27-30. || Die mikros. Besch. dcr Meteoritcn, 1883, i. 10. THE GREENLAND BASALT. 203 The descriptions are in part taken from the writings of others, in part from sections In 'longing to the Whitney Lithological Collection, and in part from sections very kindly sent 11113 by Professor J. Lawrence Smith on his own motion. These sections were the ones which had been used in the preparation of his "Memoire sur le fer natif du Greenland, et sur la dolerite qui le reuferme." * One section, from Assuk, is composed of a gray grouudmass, sprinkled with little rounded spots of a darker gray color, and porpliyritically holding grains of feldspar, magnetite, and iron. The groundmass is composed of predominating minute augite crystals, in a matrix of clear glass, containing minute feldspars and elongated trichites, similar to those seen in quartz and iron ores. The structural appearance is that of a mass out of which the pyroxene material had mainly crystallized, leaving a colorless gla-i.s, which in part had yielded feldspar crystals before congelation. The feldspar crystals are, so far as observed, all plagioclase. A greenish secondary product not only occurs in association with the iron ores, but also in detached masses and bordering fissures. Its color varies from a bright grass-green to a dull dirty-green. Occasionally it is found to be isotropic, but oftener to exhibit aggregate polarization, and it may be classed under that convenient name for these variable secondary products viridite. Little, rounded pale-pinkish isotropic grains occur. They are apparently foreign, and are considered to be garnet. A few large porphyritic crystals of feldspar were seen, which are filled in the interior portion with inclusions microlites, magnetite, glass, etc. The darker rounded masses observed in the section by the naked eye appear to be of the same composition as the rest of the section, but with smaller crystals on the whole, and with much finely-disseminated magnetite dust. This rock has been described by Steenstrup f and To'rnebohm, J the former giving a plate. Tornebohm regards the augitic mineral as enstatite, stating that it is optically orthorhombic. In the section above described, the mineral is clearly monoclinic in its optical characters, although it is perfectly possible that a rhombic pyroxene exists in connection with the augite. The iron ores occur in small rounded and irregular grains, partly native iron, partly magnetite and pyrrhotite. Usually a border of mag- netite surrounds the metallic iron. The Ovit'ak basalt (dolerite) is described by Tornebohm as composed of plagioclase, augite, olivine, titauiferous iron, and a glassy interstitial material. The augite is in pale, clear-brown, almost colorless, irregular particles between the feldspars. Olivine is found sparingly in little grains, which as a rule are fresh and unchanged. Bubble-bearing glass inclusions occur in the augite, olivine, and feldspar. The titaniferous iron is in elongated staff-like masses. The interstitial glassy masses appear only sparingly in the angles, and as wedges between the above mentioned minerals. When fresh it is of a fawn color and usually filled with microlites or dark spheres. Besides these minerals there occur metallic iron, pyrrhotite, and a silicate rich in iron. This last varies from a green to a dark-brown color. The metallic iron appears, in part, in silver-white grains, often associated with magnetite, and sometimes with schreiber- site. The pyrrhotite has in reflected light a yellowish-gray color, and is in larger and smaller grains associated with the other iron ores. The silicate rich in iron falls into two divisions : one a beautiful grass-green color, isotropic, and allied to chlorophaeite ; the other a rusty-brown mass, sometimes isotropic, and sometimes anisotropic, and here referred to hisingerite. * Aim. Cliimie Phys., 1879 (3), xvi. 452-505. f Min. Mag., 1877, i, 143-148. { Bibang K.ni-1. Svrnskii \ctiMis. Akad llamll., 1878, v., No. 10, pp. 18-21. Ibid. pp. 1-22. 204 BASALT. Only a few additions will be made to Tornebohm's description from Dr. Smith's sections. The Ovifak sections have the usual structure of a diabase or dolerite ; divergent crystals of plagioclase lying in and dissecting the irregular masses of pale brown augite, iron ores, olivine, etc., which form the interstitial material between the feldspars. The minerals are the same in general characters as those described by Tornebohm. In some cases the glass shows the globulitic structure common in basaltic glass. This basalt is more or less altered in the different sections, presenting many of the characters of a diabase, and the green and brown silicates, replacing glass, olivine, iron, etc. Much graphite occurs in scaly aggregations of a black color with a lustrous reflec- tion in reflected light, and associated with a brown and violet-red mineral which has been referred by Tornebohm to spinel ; but in the section examined by myself, part has been found not to be isotropic, and has been considered by Dr. Smith to be corundum (1. c. pp. 484-486). The reader is further referred to the before-mentioned full and excellent descrip- tion of Tornebohm for a more extended study of this basaltic rock; as well as to the writings of Tschermak.* One section in the Lithological Collection shows a grayish-white groundmass filled by rounded grayish-black masses. These dark spots are seen under the microscope to be composed of plagioclastic feldspars, filled with an irregular network of granules and masses of magnetic and native iron, the whole closely resembling the structure of some portions of the Estherville meteorite (Plate III. fig. 6). The interstitial portions between the rounded feldspathic-iron masses are rilled by the normal basalt, composed of ledge-formed plagioclase crystals, cutting a mass of yellowish-gray augite grains, violet-brown globulitic glass, magnetite, and the viriditic products. In some parts of the section the large plagioclase crystals are free from the iron, and contain glass inclusions and minute pores. A little olivine, some large augites, and yellowish-brown hisingerite (?) was seen in this portion of the section which has a doleritic or diabasic structure, while other portions have that belonging distinctively to the fine-grained basalts. Another section from the same hand-specimen shows in part of its mass the same basaltic structure as the preceding, of plagioclase, augite, magnetite, base, and secondary materials ; but the remaining portion is a coarsely crystallized mass of olivine, plagioclase, augite, iron, and magnetite. The olivines are in irregularly rounded grains, traversed by fissures. They are sometimes clear, and at others stained yellowish, and are altered along the fissures to a yellowish and brownish serpentine. The augites are pale-yellowish, and with the olivines contain bubble-bearing glass inclusions, iron, magnetite, etc. The usual secondary products occur to some extent. Some of Professor Smith's sections have parts similar to these last two sections, except the coarsely crystalline olivine-bearing portion; but his are more altered, and contain a larger amount of secondary products. Two of Dr. Smith's sections from Pfaff-Oberg are seen to be composed of lath-shaped, divergent plagioclase crystals, lying in a granular groundmass of augite, olivine, etc., with various secondary products. In one section is a large grain of iron, of an irregular cel- lular structure, and holding in its cells pyrrhotite, olivine, feldspar, etc. The preceding descriptions show that the coarse and fine crystalline structure * Miu. Mitth., 1874, pp. 171-174. THE METEORIC BASALTS. THEIR STRUCTURE. 205 is not dependent on age, or on any especial depth of the mass at the time of the crystallization ; also that diabase, dolerite, and basalt are not distinct in age, but iiifivly relative terms, indicating coarseness in crystalline texture and extent of alter- ation; for sections of these Greenland basalts could be pronounced, by taking certain portions of them, to be basalt, dolerite, diabase, and possibly gabbro. Since this work is published in parts, it has seemed best to place in the first portion, so far as possible, all relating to meteorites, and to end the first part before taking up the terrestrial basalts. Owing to the views of Professor Tschermak, that nearly all the mete- orites are tufas, the preceding descriptions are affected by that view, since most of the microscopic study has been done by him. It appears to the writer that the basaltic meteorites display in general the structure of friable, rapidly crystallized basalts, apparently quickly cooled, and never bound together by the subsequent products of alteration; few if any of them being fragments!. From this point of view, their general structure in the basaltic variety would be described as divergent, lath-shaped plagio- clase feldspars, lying in a groundmass of pyroxene (augite, diallage, and enstatite) grains, with some base, feldspar, and iron ores. So far as the gabbro type of the meteorites is concerned, the description of the Bishopville form would serve as a general statement of their collective characters, varied by the predominance of any one of the mineral constitu- ents. The Bishopville form is certainly not fragmental in structure, and it does not seem to the Avriter that the other meteoric gabbros are so ; hence they may be defined as crystalline-granular masses of feldspar, pyroxene (au- gite, diallage, and enstatite), with various ores of iron, and with or without olivine. In these, however, certain of the constituents may predominate, to the partial or complete exclusion of others. This is no more than the observed variation occurring in different portions of the same terrestrial rock. Although mineralogically the basaltic meteorites could be divided into many varieties, the same as the peridotites have been, it seems to the writer unnecessary. The terrestrial basalts were divided in the first place chiefly on structural characters and differences in external appearance, and the recently introduced terms, norite, olivine-giMro, and olmne-iiori/r, appear to be superfluous and unnecessary, although consistent with the common mineralogical nomenclature of rocks, since structurally all can readily be classed under the variety gabbro. 206 BASALT. Many changes in the arrangement of the meteorites may hereafter be made by the writer, if ever opportunity should be afforded for an ex- tended microscopic study of them. At present he has tried to arrange them as best he could with the means at his command. Although all the chemical analyses found of the basaltic meteorites have been arranged in a table, they are too few and too imperfect for any satisfac- tory discussion. SECTION IT. The Pscudo- Meteorites. A NUMBER of supposed meteorites have been described, which so far as their general characters and chemical composition show, belong to the species trachyte and rhyolite. For these the meteoric origin has been denied in every case, and perhaps the Igast stone is the only one which has any claims to be considered even of doubtful meteoric origin. Waterville, Maine. This pseudo-meteorite has teen studied by the present writer. It is in the form of a small triangular cinder-like mass, cellular, laminated, and on the fresh fracture, of an ash-gray color. The laminated appearance is produced by a series of flattened cells surrounded by a black vitreous mass. The original surfaces are coated with a gray, red-brown, and bluish-black crust formed by fusion. It was claimed that this stone was picked up sbortly after falling, hence it became necessary to examine its characters to see how long it might have been exposed to atmospheric action. The portion of the fused crust which lay uppermost on the ground is seen under a lens to have been worn and polished the same as siliceous rocks are when long exposed to rain ; while the remaining parts are found to be coated to some extent by earthy material, the same as rocks are when lying in a dry, sandy soil. Its cavities contain in places a fine, brown, matted mass, formed by the fibres of growing plants, and under the microscope their vegetable character can readily be distinguished. The specimen, then, when picked up by Captain Crosby, could not have been a newly detached mass, but had been for a long while partially buried in the soil, and of course could not have been a portion of the meteor seen shortly before the specimen was found. It remains, then, to consider the very improbable supposition is it a fragment of a meteorite which fell at some former period ? Microscopically it is seen to be a cellular, glassy mass, which has begun to devitrify, and presents the appearance of a slag-like body which has been long exposed to the action of atmospheric agencies. The sections were cut across the lamination, and showed a ihiHal structure parallel to it. A few quartz grains which were cracked and fis- sured were, seen. Near the fissures numerous ferruginous globulites had been de- veloped, and the quartz showed evident signs of having been exposed to strong heat. THE PSEUDO-METEORITES. 207 Adjacent to the flattened, as well as some other cells, is a black and brown ferruginous material The sections show not the slightest characters belonging to any meteorite that has yet been examined microscopically, either by myself or by others, so far as can bo ascertained by their published descriptions. It is apparently a slag.* Richland, South Carolina. This so-called meteoric stone is reported to hav fallen in 1846. This when cut was, according to Professor C. U. Shepard, of a "uniform yellowish-white color, much resembling that of common fire-brick. A few minute grains "of transparent quartz are visible throughout its substance, which is otherwise perfectly homogeneous. It is close-grained and rather firm in texture." This description, and the chemical analysis given by Shepard, coupled with one by Rammelsberg denotes a structure similar to that of the rhyolites, for such a description could be given of many of them.f Jtammelsberg regards the Richland stone as a clay, or possibly a fragment of a brick. A microscopic examination by a competent lithologist ought to readily deter- mine the character and origin of this stone. Igast, Livonia, Russia. This stone is looked upon by Professors Grewingk and Schmidt as an authentic meteorite, and they made a chemical analysis of it, showing that it contained a little over eighty per cent of silica. $ Professor F. J. Wiik also accepts it as a meteorite, and states that in the thin sections it shows a fine-granular, dark-colored groundmass, the dark color owing to little magnetite, porphyritically inclosing larger crystals of quartz, orthoclase, and oligoclase. The quartz contains fluid cavities with movable bubbles, and the plagioclase shows fine parallel cleavage lines as well as the usual twinning. By a high magnifying power is shown in the groundmass little colorless elongated crystals, and minute crystalline grains. Professor E. Cohen regards it as a doubtful meteorite. Lasaulx describes this as a stone rich in a basaltic glass base, in which lie inclosed numerous grains of plagioclase, microcline, and quartz. The groundmass is composed largely of a brown glass, rich in magnetite grains, some showing quadratic sections, and others a dendritic structure. The groundmass further contains numerous little spear- or ledge-shaped plagioclase crystals, and yellowish-green irregular grains of augite all showing fluidal structure. The entire groundmass appears as the product of the fusion of quartz and feldspar, the rudiments of which are now inclosed, witli the later crystallization of plagioclase and augite out of the molten magma. Many of the crystals show distinct rounding through the fusion of their edges. The larger plagioclase fragments are mostly ragged, slashed, and irregular, while the minute quartz grains are commonly perfect, and smoothly rounded. The plagioclase crystals are generally clear and free from inclusions ; only an external rim of disjointed glass inclusions lies about them. The brown glass penetrates into the fissure in the * Am. Jour. Sci., 1883 (3), xxvi. 36-38. f Proc. Am. Assoc. Adv. Sci., 1850, iii. 147, 148. + Arcliiv Nat. Liv-, Elist-, Kiirlands, 1S 1851 ( 2 )> xi - 39 > 40 - % Jour. Prakt. Chetnie, 1863, Ixxxv. 87, 88. Am. Jour. ScL, 1847 (2), iv. 353-356. || G. W. Hawes, Geol. of N. H., part iv., p. 24. EXPLANATION OF THE TABLES. TABLE I. Chromite and Ficotite. pp. ii-v. THIS table contains one hundred and twenty analyses of chromite and picotite, arranged in the ruling order of the percentage of chromic oxide. Since the object of the table is to show the mutual relations of the two minerals, and their variations, many of the analyses given of chromite are of the more inquire forms, commercial ores(()- TABLE II. Siderolite. pp. vi-xv. This table contains one hundred and ninety-three analyses of meteoric and terrestrial irons, arranged in the descending order of their percentage of iron. The irons which are supposed to be meteorites, but which have not been known to fall, have Ixjen marked by an interrogation point placed after the term Mi-te.ii-ite. NII variety names proper occur in this species; but for convenience the meteoric irons kimwii to have fallen, the supposed mete-uric irons, and the terrestrial irons, are distinguished from one another by terras placed in the "Variety" column. When several analyses are given for the same locality, no attempt is made to arrange them beyond this : the analysis first found in the search for the analyses is placed first, and the others follow in the order in which they were seen ; except in cases in which the analyses strikingly differed in value, owing cither to internal evidence or to the reputation for accuracy of the analyst ; then the best is placed first, but the order of the others still remains in the order in which they were found. TABLE III. Pallasite. pp. xvi, xvii. This table contains twenty-four analyses of meteoric and terrestrial pallasites. The doubtful meteor- ites are designated as in the preceding table, while the terrestrial forms are given their proper variety name, Cumberlandite. But few of these analyses are accurate exponents of the constitution of the rock mass, the majority being rough approximations only. The analyses are arranged in ascending order of the percentages of silica. TABLE IV. Peridotite. pp. xviii-xxxi. This table contains two hundred and forty-four analyses of terrestrial and meteoric peridotites. In the " Variety " column is given the name of the variety so far as known, and when the specimen is a meteorite it has been designated by an asterisk prefixed to the variety name. The meteorites whose variety is not known are designated by the term Meteorite, and the terrestrial peridotites, whose variety is also unknown, are given the names which the analysts have applied to them. The analyses have been arrangL-d in the order of the percentages of silica ; but when more than one exists for the same locality, they have been arranged as stated for Table II. The specific gravities in this and the other tables have been taken from any available source, when the analyst has given none ; but it has been found impracticable to designate the source from which they were obtained, although many are from C. Rumler's determinations, which with analyses are to be found in the works and tables of Partsch, Buchner, Rammelsberg, and Roth, to which I am deeply indebted* Many analyses of meteoric forms have been made in such a manner that no determination of the complete chemical constitution is possible, owing to the omission of necessary data for recalculation, and all such have been omitted. Many others have been recalculated with more or less approximation to cor- rectneM, varying according to the data; matters in which the numerous analyses of Dr. J. Lawrence Smith have been particularly unfortunate. The recalculations have mostly been made by the aid of a four-place table of logarithms, and therefore pai-take of its imperfections. TABLE V. Part I. The Meteoric Basalts, pp. xxxii, xxxiii. This part contains thirty -one analyses, arranged in order of their percentages of silica. 27 TABLES. ii ANALYSES OF CHEOMITE AXD PICOTITE. TABLE I. Analyses of Name. Locality. Analyst. Publication. Cliromite. Picotite. Picotite. Picotite. Picotite. Picotite. Cliromite. Kynouria, Greece. Knsakover, Hohemia. Kosakover, Bohemia. Hoihcim, Bavaria. L. Lhcrz, France. L. Lherz, France. Near Athens, Greece. A. Christomanos. F. Farsky. Hilger. F. Sandberger. A. Damour. A. Christomanos. Berichte Cliem. Gesell. Berlin, 1877, i. 343-350. Verh. Geol. Reich., 1870, pp. '207, 208. Neues Jahr. Min., 1866, p. 399. Nencs Jabr. Min., 1806, p. 388. Bull. Sue. Ge'ol. Frame, 1802 (2), xix. 414. Berichte Chem. Gesell. Berlin, 1877, i. 343-350. Chrnmite. Chroroite. Cliromite. Pinuus, Greece. Alt-Orsowa, Hungary. Delos, Grecian Archipelago. Alfr. Ilofmann. A. Christonianos. Neues Jahr. Min., 1873, p. 873. BcTichte Chem. Gesell. Berlin, 1877, i. 343-350. Cliromite. Seres, Macedonia. Cliromite. Cliromite. Cliromite. Cliromite. Chromite. Cliromite. Cliromite. Cliromite. Cliromite. Cliromite. Cliromite. Cliromite. Gythion, Greece. Cerign, Ionian Isles. Hungary. Mt. Il3'mettus, Greece. Australia. Salamis, Greece. Corinth, Greece. Vrysi, Greece. Vache Island, \V. Indies. Var, France. Loukissia, opp. Clmlcis, Greece. Loutraki, Greece. tl ft - 3. Clouet.* A. Christomanos. J. Clouet, A. Christonianos. tt tt P. Berliner. J. Clouet. A. Christomanos. Ann. Cbimie Phys., 1869 (4), xvi. 90-100. Berichte Chem. Gesell. Berlin, 1877, i. 343-350. Ann. Chimie 1'livs., 1809 (4), xvi. 90-100. Bcrichte Chem. Gesell. Berlin, 1877, i. 343-350. tl H H It Ann. Cbimie Phys., 1821, xvii. 55-04. Ann. Chimie Phys., 18B! (4), xvi. 1)0-100. Berichte Chem. Gesell. Berlin, 1877, i. 343-350. Cliromite. Cliromite. Cliromite. Cliromite. Cliromite. Cliromite. Chromite. Cliromite (Magnetic Chrome Sand). Cliromite. Cliromite. Chromite. Chromite. Chromite. Cliromite. Chromite. Chromite. Chromite. Locris, Greece. Perachora, Greece. Peky, Greece. Bare Hills, Baltimore, Md. Alt-Orsowa, Hungary. Christiania, Norway. Shetland Isles. Chester, Penn. Prontheim, Norway. Volterra, Tuscany. California. Cerasia, Euhcea. Haziskos, Greece. Var, France. Volo, Thessaly. Troezene, Greece. Epidaurus, Greece. 100.00 ,V. :)l 10.18 7.80 24.00 1'.98 100.00 4 08 68.00 In. /i 8.00 24 90 200 101.20 80.80 11.78 '.I.Stl 2.72 7.00 4.85 5.50 FeC(). = 87.76. 100.20 14.78 6.13 10.80 2a.oe 12 05 6.17 10.55 CO. 2 2.27, ll.,O 1.00. 99.05 lii.110 21.101 17006 22.499 14.211 8.300 99.317 :: s.-, 85.40 17.7:! 1081 26.70 7.20 CO., = 2.80. 100.49 i 12 -is 71 17 --< 560 '.! ,sa CO , 35.05. 100.28 tr:iri>. 10.60 21.16 tract 1 . 11 10 12.04 24.36 CO.j 18.14. 100.46 0.48 10.92 :;i L'II 27.72 14.79 11.30 Mnr,O i =4.18. 100.59 M 77 1 1 S.-, 31 48 29.00 7 ::o 100.00 20.60 ] ' I IS 3275 23.84 7.67 2.01 CO.j 1.03. 99.88 18.00 17.IH 33.20 28.40 8.00 100.00 19.61 '.' 18 3360 "171 403 8.80 COj trace. 10063 .,., ?l 18.68 ::i 7"> 01)0 IB 81 943 2.02 100.35 24.71 7.81 35.60 28.62 3.56 1.55 CO 2 0.62. 99.47 81.80 30.00 37.20 6.00 loo.oo 1:: !." ! .">;! 8700 ::i 7'i 2 53 10000 17 no 8.08 3731 380 :;.". l" 2.82 trace. Mn,Oj 1 12. 1(025 7.70 16412 ::> 1" 106 2740 8.53 98.73 27. K] 10.47 39.06 0.85 1805 2.10 Mn.,0 a 1.45. 09.80 688 1407 :;n :;;', 075 27 70 11 04 !)'.! 42 20.14 1000 89.60 2820 l.l 100.35 10689 l::.oo-_> ::'.514 30.004 10590 !f.i.ll6 20.6M 17.005 39.574 10.558 4.19 98023 4.80 13.23 4000 37 77 420 KlOOO 10.15 10.80 41.00 23 14 8.85 100.00 41.55 02.02 1.25 104.82 12.00 21 28 4200 10 72 500 100.00 I'.isl 42 13 83.98 475 100.66 |:: M 14.88 42.20 2384 648 100.00 1097 1 "> ''7 42 00 19.02 <)31 2 20 i!) 97 22.0 I 12 72 4280 1933 202 1 13 100.64 _'u.:;o 4300 3470 200 100.00 81.19 3.18 43.20 3062 2 HI trace. 100.33 9.00 12.86 4323 20 HO 095 4 70 CO, 088 99.03 11.53 21 oii 4340 2060 4 87 101.42 20.15 7.77 43.50 20.92 6.02 trace. 99.20 10.23 16.26 4.'! 70 21 27 542 Mn,Og 1 95 100.32 2384 0.77 43 80 81 55 99.96 4.31 a 22.41 15.67 44.15 5.78 11.70 99.77 7.47 17.:W 41.20 2493 6 10 loo.oo 111 14 300 4479 31 85 200 10084 0*08 1 1 M) 1 1 ^1 21 41 650 574 CQ 2 I2i> 1IKI-") 18.86 i'.'.Ki 4491 18 '17 083 98 25 5.40 4.09 46.00 4231 3 20 10000 V.J .,._> 11 lit 4510 14 5') <; to 99.96 10 1-2. 028 |.", :;' ':'.' i 7 !' 42 9871 840 23.77 4540 21 88 ."l >!', 99 91 4.534 1M 0.28 4546 I:: .;'.i 10242 0.00 2.06 16.60 4278 300 10000 820 16.08 46.90 3508 99.81 20.00 20.55 464J7 1" D8 10025 8.71 14.28 47 30 23 17 6 20 'i'i 70 ::.:;:; 427 47.50 |.~, >_> 10032 !i:;o 6.00 4750 3"i 70 1 50 10000 8.98 2.88 47.66 trace. :;l sr 5.53 W.71 - 12.00 15.01) 4-> 7-' |s :;:', 526 10000 ... 10.20 4.68 49.00 ''.1 ''I) 700 10008 (1.77 18.40 !' ri ''3 27 707 1 nil. IK) 11.80 18.13 4 !i 7.-, 21.28 100 40 21.67 8 IK) 50.06 1 .". 70 3 ia '.'li 1 1 14''.') 1 HI '17 '", '10 ) --, 4 80 CO 75 99 78 5.00 11.53 60 sii ''7 00 4 90 'i') ':: 11.87 16.72 r,o so 16.92 1 '10 '.i'i '! 0.14 17.05 51.50 22 75 :: :,i; 10000 IV ANALYSES OF CHROMITE AND PICOTITE. TABLE I. Name. Locality. Analyst. Publication. Cliromite. Cliromite. Cliromite. Vaclie Island, W. Indies. Chester Co., Penn. Ural. J. Clouet. Henry Seybert. Ann. Cliimie Phys., 1809 (4), xvi. 00-100. Am. Jour. Sci., 1822 (1), iv. 321-323. Cliromite. Cliromite. Cliromite. Cliromite. Cliromite. Philadelphia, Penn. Tanagra, Greece. Polyliieron, Macedonia. Monterey Co., Cal. Papades, Eubcea. P. Berliner. A. Christomanos. E. Goldsmith. A. Christomanos. Ann. Chimie Phys., 1821, xvii. 55-04. Berichte Chem. Gesell. Berlin, 1877, i. 343-350. Proc. Phila. Acad. Nat. Sci., 1873, p. 305. Berichte Chem. Gesell. Berlin, 1877, i. 343-360. Cliromite. Styria. J. Clouet. Ann. Chimie Phys., 1869 (4), xvi. 90-100. Karaliissar, Asia Minor. Cliromite. Cliromite. Wiasga, Ural. Ural. A. Laugier. Ann. Mus. Hist. Nat., 1815, vi. 325-331. Kokscharow's Material Min Russ 1800 v 163 Cliromite. Cliromite. Hibbard's,near Media, Delaware Co., Penn. Ural. F. A. Genth. Sec. Geol. Survey Penn., B, 1874, p. 43. Kokscharow's Material Min Russ 1866 v 103 Cliromite. Albania. A. Christomanos. Berichte Chem. Gesell. Berlin, 1877, i. 343-350. Chromite. Ann Mines 1829 (2) v 310 (ante p 185) Cliromite. Cliromite. Cliromite. Cliromite. Cliromite. Cliromite. Cliromite. Cliromite. Pirotite (Chrom- picotite). Cliromite. Cliromite. Cliromite. Vatondos, Eubo3a. Broussa, Asia Minor. Plattsburg, N. Y. Texas, Lancaster Co., Penn. Smyrna, Asia Minor. Krieglacli, Steiermark. Pyli, Eubcea. Shetland Islands. Dun Mountain, New Zealand. Texas, Lancaster Co., Penn. Broussa, Asia Minor. Tarasska Ural. A. Christomanos. P. Collier. Franke. A. Christomanos. M. H. Klaproth. A. Christomanos. T. Thomson. Theodor Petersen. C. F. Rammelsberg. A. Christomanos. Berichte Chem. Gesell. Berlin, 1877, i. .'!43-350. Am. Jour. Sci., 1881 (3), xxi. 123. Rammelslierg's Ilandbuuh der Mineralchemie, 2d ed., 1875, p. 142. Berichte Chem. Gesell. Berlin, 1877, i. 343-350. Mineral Korper, 1807, iv. 132-136. Berichte Chem. Gesell. Berlin, 1877, i. 343-350. Ann. Mines, 1827 (2), i. 280. Jour. Prakt. Chemie, 1869, cxv. 137-140. Handbuch der Mineralchemie, 2d ed., 1875, p. 142. Berichte Chem. Gesell. Berlin, 1877, i. 343-350. Kokscharow's Material Min. Russ , 1806 v 163. Cliromite. Mt. Kossipnaia, Ural. (1 X U tt tt Cliromite. Cliromite. Cliromite. Cliromite. Viatka, Russia. Alt-Orsowa. Hungary. O'ita, Japan. Ural. J. Clouet. Alfr. Hofmann. T. Haga. Ann. Chimie Phys., 1869 (4), xvi. 90-100. Neues Jahr. Min., 1873, p. 873. Jahresb. Chemie, 1881, p. 1302. Kokscharow's Material Min. Russ., 1866, r. 163. Cliromite. Cliromite (Crystal- lized). Cliromite. Cliromite (Chrome Sand). Cliromite. Cliromite. Clmimite. Cliromite. Asia. Baltimore, Maryland. Haziskos, Greece. Chester, Penn. Mourtia, Eubcea. Baltimore, Maryland. Texas, Chester Co., Penn. Ural. Alfr. Hofmann. Hermann Abich. A. Christomanos. Isaac Starr. A. Christomanos. L. E. Rivot. T. H. Garrett. Neues Jahr. Min., 1873, p. 873. Ann. Physik Chemie, 1831, xxiii. 335-342. Beriehte Chem. Gesell. Berlin, 1877, i. 343-350. Am. Jour. Sci., 1852 (2), xiv. 47. Berichte Chem. Gesell. Berlin, 1877, i. 343-350. Ann. Chimie Phys.,,1850 (3), xxx. 200-203. Am. Jour. Sci., 1852 (2), xiv. 46. Kokscharow's Material Min. Russ., 1866, v. 103. Cliromite. Ural. Kokscharow's Material Min. Russ., 18C6, v. 102. Cliromite. Cliromite. Berezof, Siberia. Massachusetts. A. Moherg. C. H. Pfaff. Jour. Prakt. Chemie, 1848, xliii. 114-128. Jour. Chemie Physik, 1825, xiv. 101, 102. ANALYSES OF CHROJSUTE AND PICOTITE. Continued. Sp. Gr. ALA- MgO. OA FeA FeO. SiOj. CaO. Miscellaneous. Total. 51 03 4840 100.00 ') 7->o 61.562 36.14 2.901 MnO = trace. 99.326 6 20 !' 1'' 51 60 2406 635 100.33 9 70 51 00 3720 2.90 99.00 18.90 7 81 61 80 "4 72 2.05 0.41 100.69 11 01 17 45 62 12 1676 2.00 99.M !4 HUT 2 18 ].| .>!) 62 12 1524 12 12 09.00 r QO 1'' (I' 1 5 l> 50 ''4 7'' 390 O'.l 7 1 3 0"' I'l 7'' 5'' 88 1 22 24 27 12 05 100.00 800 11 58 5300 '1 '12 250 100.00 762 1'' 31 5300 >4 112 2 15 100.00 805 1098 68.00 "4 '.!' 305 100.00 1100 .-,;;.< H) 34.00 1.00 MnO = trace, Loss = 1.00. 100.00 O.'.H) 14 8*> .">:', li; '1 IK> 1010 100.08 4 78 698 053 6336 741 2ii.i;t NiO., = 0.14, CoOo = trace, 100.45 1 30 1526 5360 1083 11.35 MnO = 0.39. 101.34 17 75 203 6390 25.00 0.80 100.14 11 14 704 5400 18.08 7.30 CaCO 2 = 2.44. 100.00 9 02 5357 6408 25661 4.833 08.051 785 992 5442 24.88 4.41 101.48 11 S2 604 54 55 25.75 1.95 1(0.12 5(1') 0941 64944 31 507 3.731 3.405 100.278 675 939 65 14 2888 99.16 482 1058 5550 2625 262 060 100.37 4 00 600 55.50 33.00 2.00 Ignition = 2.00. 1)8.50 206 721 6584 2480 9.52 00.43 1300 60.00 3100 trace. 100.00 4 115 12 13 1408 66.54 18.01 MnO 0.46, CoO+NiO 101.22 086 989 6655 3023 trace. 97.63 253 1237 5070 2600 2.04 100.54 580 1238 66.80 2010 4.20 99.34 ( 480 !' 7-"> 67.20 20.00 5.80 100.61 ' 4.60 633 6692 2700 5.20 100.05 f 620 12:58 56.60 2007 5.00 100.25 1000 1102 68.00 18.18 2.20 100.00 1 1 UN; 2.018 68.0'JO 21.337 3.639 MnO 0.002. 99.688 450 080 9 17 5930 28.27 1 58 !t9. 12 000 1029 59.60 22.41 6.80 100.06 10001 3.130 60.022 20.192 0.026 MnO = 5.20. 09.171 1185 7 45 6004 2013 00 45 840 2.19 60.50 28.75 045 trace. 100.29 0.928 60.836 38.952 0.019 NiO 0.10. 100.425 1345 631( ? ) 61.50 1895 0775 09.0?5 1.96 6337 3004 2.21 202 9'J.OO 4.508 63.39 38.66 NiO 2.28. 104.33 050 12.12 6380 2034 300 0970 ( 5.04 6400 103 ALol+Ftio 2933 99.40 | (5.15 (i-J. -Jo 0.95 30.05 09. 40 ( 6.28 63.40 2.00 28.00 100.88 10.83 6.68 6417 1842 0.91 101.01 77.00 9.00 AloOj+SiOj 15.00. 101.00 VI A CLASSIFIED LIST OF COMPLETE (BAUSCH) TABLE II. Variety. Locality. Analyst. Publication. Sp. Gr. Fe. Ni. Co. P. S. P.Fe.Ni. Meteorite ? Meteorite 1 Meteorite ? Meteorite ? Meteorite ? Meteorite ? Meteorite ? Meteorite ? Meteorite ? Meteorite ? Meteorite ? Meteorite ? Meteorite ? ri Meteorite ? M (i Meteorite ? .V>. Am. Jour. Sci., 1871(3). ii. 335-338. Am. Jour. Sci., 1849(2), vii. 449. Am. Jour. Sci., 1880 (3), xix. 381, 382. Am. Jour. Sci., 1809 (2), xlvii. 230-233. Am. Jour. Sci., 1877 (3), xii. 439. Trans. St. Louis Acad., 1800, i. 023. Buchncr, Meteoriten, 1863, p. 193. Comptes Kendus, 1875, Ixxxi. 597. Am. Jour. Soi., 1864 (2), xxxviii. 385, 386. Comptes Kendus, 1868, Ixvi. 573, 574. 7.84 7.818 7.05 7.0-7.17 7.40 7.0698 7.42 0.07 0.129 0.14 0.001 0.085 0.13 0.23 7.901 7.835 ANALYSES OF METEORIC AND TEERE3TBIAL KOCKS. vil Siderolite. c. Cu. Sn. Cr. Si. Al. Ca. Mg. Mn. Cl. As Insul. Loss. Umlet. M iscellaneous. Total. trace, trace. trace. 0.09 trace. 00.89 09.97 10000 100.52 99.00 99.36 100.03 101.08 100.00 100.00 10000 100.00 100.00 100.00 99.80 09.60 100.00 100.931 100.00 99.121 100.00 99.940 99.59 99.999 98.10 99.82 100.00 99.67 100.00 10007 99.78262 09.03 99.82 100.48 99.89 0.20 Accordingto Meddle itcon- tains nickel, potassium, nml tracts of sodium, silicon, sulphur, cnrhon, phosphorus ! and tin ? Phil.MaL'.,18(i2(4),xxiv. 541. Ni, CrjO,, Co, Mg, and P = 210. 1.50 trace. 105 1.60 Graphite <<,". trace. Co Si and loss 0.43. Co and Si = j ^ 0.00018 Si0. 2 0.0056 0.50 Al,0 3 0.61015 CaO O.TOH15 .... .... OA trace. .... .... 0.20 trace? 0.57 1 44 trace. 100 0.017 002 :::: trace. 0287 trace? trace. .... .... trace. 058 0735 .... trace. 0.10 The carbon occurs as gra- phite. . .... trace. 2.2 015 ta 0.32814 SiO., 0.20 CaO MgO .... trace. 0. 30 trace. A CLASSIFIED LIST OF COMPLETE (BAUSCH) TABLE II. Variety. Locality. Analyst. Publication. Sp. Gr. Fe. Si. Co. P. S. P.Fc.Ni. Meteorite ? ti tt tt tt tt tt tt tt tt n Meteorite. Meteorite "> it Meteorite Meteorite jion River, Great Namaqualand, South Africa. Scliwetz, Weich- sel Hiver, Prus- sia. \elson Co., Ken- tucky. \\Mintmannsdorf, Saxony. ,iek Creek, Dn- vidson Co.,N. C. Coalmila, Mexico. \ot known, 'ittsburg, Penn. Tabarz, Thurin- gia, German v . GuilfordCo.,N"C. Vngarn,Jeniseisk, Siberia. Caille, Var, 1'rance. Southeastern Mis- souri. lio Juncal, Ata- caina, Cliili. 3emdego Creek, Baliia, Brazil. Sizipilec, Mexico. 3raunau, Bohe- mia. Dakota. Cosby Creek, Cocke Co., Tennessee. Cliulafennee, Cle- burne Co., Ala. Atauama, Chili. Lenarto, Hun- gary. Rowton, Slirop shire, Eng. Santa Rosa, New Granada. C. U. Shepard. C. Rammelsberg. J. L. Smith. ( F. E. Geinitz. ( G. E. Lichtenberger. J. L. Smith and J. B. Mackintosh. J. L. Smith. C. U. Shepard, Jr. F. A. Genth. W. Eberhard. C. U. Shepard. M. A. Gobel. f L. E. Rivot. { J. Boussingault. [ V. de Luynes. C. U. Shepard. A. A. Damour. JFickentscher. W. II. Wollaston. L Wolilcr & Martius. C. II. L. v. Babo. Duflos & Fischer. C. T. Jackson. (C. A. Joy. { C. Bergmann. !_ C. U. Shepard. J. B. Mackintosh. E. Ludwig. f J. Boussingault. I A. Wherle. [ P. A. v. Holger. W. Flight. Rivero and Boussin gault. \rn.Jour. Sci., 1853(2), xv. 1-4. Vnn. Physik Cherpie, 1851, Ixxxiv. 153,104. Am. Jour. Sci., 1800 (2), xxx. 240. ^euc-s Jahr. Min., 1876, pp. 008-612. Sitz.Isis, Dresden, 1873, p. 4. Am. Jour. Sci., 1880 (3), xx. 324-326. \rn.Jour. Sci. ,1869 (2), xlvii. 383-385. Vm. Jour. Sci., 1881(3), xxii. 119. Am. Jour. Sci., 1870(3), xii. 72, 73. Ann. Cliem. Pharm., 1855, xcvi. 280-289. \in.Juur. Sci., 1841 (1), xl. 309, 370. Bull Acad St Peters 7.45 7.77 93.30 93.18 93.10 93.04 94.59 93.00 92.95 92.923 92.809 92.757 92.75 92.6346 92.30 92.70 89.53 89.73 8763 92.090 92.03 91.90 95.10 88.40 91.89 91.882 91.735 91.735 91.035 91.898 9380 94.033 91.608 91.53 91.50 90.90 85.04 91.25 91.040 91.23 91.70 91.41 0.70 5.77 6.11 6.16 5.31 5.74 6.62 6.071 4.665 5.693 3.145 7.1038 6.20 5.00 9.76 9.90 7.37 2.604 7.00 5.71 3.90 8.5 6.32 5.517 0.532 7.08 5.816 6.704 4.00 4.444 7'368 7.14 8.58 8.50 8.12 8.582 * , 9.1 8.21 6.36 8.59 1.05 0.41 race. trace. 0.05 0.22 6.21 .... 0.52 0.48 0.539 0.395 0.791 trace, trace. trace, trace. 0.36 0.02 trace. 7.692 7.589 7.741 7.737 7.07 0.562 0.251 0.862 0.037 0.277 0.163 1874, xix. 544-554. Vnn. Mines, 1854 (5), vi. 554, 555. Domptes Rendtis, 1872, Ixxiv. 1287-1289. Ann. Mines, 1844 (4), v. 161-164. Am. Jour. Sci., 1869 (2), xlvii. 233, 234. Comptes Rendus, 1808, Ixvi. 509-571. Buchner, Meteoriten, 1863, p. 144. Phil. Trans., 1810, pp. 270-285. i'liipson, Meteorites, 1807, p. 94. Buchner, Meteoriten, 1863, p. 141. Ann. Physik Chemie, 1847, 1-xxii. 475-480. Am. Jour. Sci., 1863 (2), xxxvi. 259-261. Ann. Chem. Pharm., 1853, Ixxxvi. 39-43. Ann. Phyrik Chemie, 1857, c. 254,255. Am. Jour. Sci., 1842 (1), xliii. 354-363. Am. Jour. Sci., 1880 (3), xx. 74. Denks. Wien. Akad., 1872, xxxi. 187-1115. Comptes Rendus, 1872, Ixxiv. 1288, 1299. 7.428 | 7.64 -.015-7.112 7.697 7.731 7.73 7.468 trace. 0.62 trace 0.21 .... 5.00 > .9 1.58 0.529 trace trace 0.809 0.332 0.37 7.7142 7.952 | 0.01 0.01 0.190 0.089 7.257 0.222 | 0.50 0.41 0.17 0.45 7.7580 7.73 7.79 0.605 3.59 0.371 ' 77 worterbuch, 1841, p 423. Zeit. Phys. Math., 1830 vii. 129. Phil. Trans., 1882, pp 891-890. Ann. Chemie Phys. 1824, xxv. 438-443. ,.j ( 7 60 ^ 7.30 j ANALYSKS OF METEORIC AND TEREESTKIAL KOCKS. IX Continual. c. Cu. Sn. Cr. Si. Al. Ca. Mg. Mn. Cl. As. Insol. Loss. Undet Miscellaneous. Total. trace. K 2 trace. 100.00 0.098 100.098 trace. 99.67 9942 9990 tract- 0962 trace. analyses. 9907 100.095 0.031 0.141 98332 100.38 Fe^Oa-f-FeO 75 9C645 trace. 0.0421 trace. 0.0505 trace. Analysis imperfect. 100.00 trace. 0.90 99.40 0.12 trace. 0.90 , O.E 9^ 99.20 100.00 0.12 trace. 0.2 5 100.00 10000 trace. trace. SiO.; trace. trace. Trace of Fe^Og. 99.70 9986 046 193 10000 10000 0.07 196 10000 9979 Cu -1 Mn + As + Ca + Mp 10000 0.003 0,0, trace. +Si+C+Cl+S=2.072. 98.34 O.OC3 trace. SiO 98.888 0" 10 0.079 0092 Graphite 798 99673 0.175 99 198 0.10 98.56 0.10 98.577 99646 trace. 9953 .... trace. 030 10038 0.002 100 10 0.01 0.77 1.63 023 061 10000 trace. 100 9 03 trace. ..-,<> I P. A. v. Ilolger. Zeit.PhysikMath.,1831, 7.61-7.71 1 83.67 7.83 n.<;u Meteorite ? Boliumilitz, Bohe- ix. 323-328. ( 92.473 5.007 235 mia. j 93.775 3.812 0.213 ii Zacatocas, Mex- [j. Mfi in nan. \ C. Bergmarm. IS. N. Manross. Am. Jour. Sci., 1831 (1), xix. 384-386. Neues Jalir. Min., 1856, p. 207. Ann. Cliemie Pliarm., 7.146 7.48 7.55 94.06 85.09 92.33 4.01 9.89 1 r 7.3 0.70 ., t 8 .... 0.81 0.84 1.65 042 ico. H. Muller. 1852, Ixxxi. 252-255. Quart. Joiir.Chem. Soc., f 7.20 \ 7.50 89.84 91.30 5.96 6.82 0.62 0.41 6.25 0.13 1 859 (l),xi. 236-240. I 7.625 90.91 5.65 0.42 0.23 0.07 A. E. Nordenskibld. Geol. Mag., 1872(1), ix. 6.30, 6.86 84.49 2.48 0.07 0?0 1.52 T. Nordstrom. 518. Geol. Mag., 1872(1), ix. 7.05, 7.06 86.34 1.64 0.35 0.07 0.22 G. Lindstrom. 518. Geol. Mag. 1872 (1), ix. 6.24 93.24 1.24 0.56 0.03 1.21 F. Wohler. 518. Neues Jahr. Min., 1879, 5.82 80.64 1.19 0.47 0.15 2.82 * It. NauckliofE. p. 833. Miu. Mitth., 1874 p. 125. 58.25 2.16 030 0.16 f 6.87 91.71 1.74 0.53 0.10 91.17 1.82 051 0.78 82.02 1.39 0.76 O.C8 59.77 1.60 0.39 i 7.92 93.89 2.55 0.54 0.20 Terrestrial Iron. Southern Green- land. J. Lorenzen. Zeit.neut.Gnol. Resell., 1883, xxxv. 695-703. I 7.57 J 7.26 92.41 95.15 0.45 0.34 0.18 006 .... trace. 95.67 trace. 0.09 702 729 92.46 0.92 1.93 0.07 059 92.68 2.54 058 001 706 92.23 2.73 0.84 94.11 2.85 107 G. Forchhammer. Ann. Pbysik Cliemie 7.073 93.39 1.56 0.25 0.18 0.67 1854, xciii. 155-159. 1642 93.16 2.01 080 0.32 0.41 . ^ 746 90 17 6 50 079" . Li. bmith. 080 88.13 2 13 107 0.25 6.36 760 92.45 288 0.4:> 0.24 1.25 {A. A. Hayes. Am. Jour. Sci 1845 (1) 6.82 83.572 12.005 Meteorite ? Claiborne, Clarke Co., Alabama. C. T. Jackson. xlviii. 145-156. Am. Jour. Sci., 1838(1), xxiv. 332-337. 5.75, 6.40, 6.50 6 035-7 944 66.56 81.20 24.708 1509 256 009 2.00 1854, xv. 252. 7 708 82 77 1432 252 026 - Cape of Good Soelheim. A Welirle. 1867, ii. 376-384. Zeit Pliysik Math 1835 7605 85.008 12275 0887 Hope. M. Bucking. (2), iii. 222-229. Ann. Cliemie Pliarm., 1855, xcvi. 243-240. Zeit Plivsik Matli 1830 7.604 7318 81.30 7890 15.23 1528 2.01 100 0.08 trace. 0.88 C T Jackson viii. 283. Am Jour Sci 1872 (3) 7 9053 80 74 1573 ii iv. 495, 496. 775 04.00 30 00 M Brazil. Oktibbeha Co W J Taylor Ixxxiii. 917-919. Am Jour Sci 1857 ( 9 ) 6854 3709 5969 040 010 Mississippi. xxiv. 293-295. ANALYSES OF METEORIC AND TEKliESTIUAL HOCKS. XV Continual. c. Cu. Sn. Cr. Si. Al. Ca. Mg. Mn. Cl. As. Insol. LOBS Undet Miscellaneous. Total. .... .... .... .... .... 0.82 0.42 0.41 1.08 o.ia 0.10 0.40 0.68 .... .... 1.34 4.78 .... Be = 0.10. Be =0.12. 08.16 99.16 100.00 100.00 100.00 100.C2 100.16 99.63 0.43, Nn.,O =0.09, NiO+CoO=0.41. Sid.. 0.00 .... 1.16 10 .... 4.37 .... 0.13 0.16 0.10 0.19 0.23 0.33 0.48 0.14 0.06 0.16 0.20 0.36 0.23 0.45 0.12 0.13 SiOi 0.20 Sid, 0.31' BIO, 0.40 Sid, OJ Sid., 0.39 SiO., 0.40 Al.,0 8 1.46 AM., l.-'l Al,0 3 Ma ALgj 1.08 Al.O. 8.79 CuO 0.60 MgO 0.33 .... 0.10 .... 6.07 2.39 077 .... U = 0.28 8.08 i'i 2:i 1.48 SiO. 2 0.90 BiO. 0.08" SiO., 1 in" AI.O,, 0.00 AIA 0.51 467 1.00 109 Sid, 0.24 1.09 SiOj 031 008 .... .... SiO, 0.04 Al,,0, O.U1 1.99 061 SiO, 0.38 SiO., 1.54" 002 2:!;: 1.74 0.48 0.18 Sid, trace, trace. 008 Silicates = 4.20. 1.31" .... trace. 0907 0401 FeSi = 2.395. Cr 2 O 8 +Mn = 3.24. 1 48 * trace, trace. trace. 0.95 .... trace. trace. 141 015 1 76 1 34 0.01 P, etc. = 3.52. .... 0.90 .... .... 0.12 0.20 0.09 XVI A CLASSIFIED LIST OF COMPLETE (BAUSCH) TABLE III. Variety. Locality. Analyst. Publication. Sp. Gr. SiO 2 . Fe. Fe 2 s . FeO. TiOj. Al.,0 3 . Meteorite? H H (1 }umber- landite. Meteorite? H If Cumber- laiulitc. Cumber- landite. Meteorite * tt H 'ucsdii, Arizona. Tucson, Arizona. Bitburg, Eifel, Prussia. Jraliin, Minsk, Russia. Atacama, Chili. j&nghult, Swe- den. Singhur, Decean, India. Anderson, Hamil- ton Co., Ohio. Krasnoyarsk, Si- beria. Atacama, Chili. [ron Mine Hill, Cumberland, It. I. Taberg, Sweden. Sierra tie Chaco, Atacama, Chili. Rittersgrun, Sax ony. Lodran, India. Hainholz, Prussia J. L. Smith. G. J. Brush. fJ. F.John. [F. Stromeyer. A. Laugier. Von Kobell and Rivero. B. Fernqvist. H. Giraud. L. P. Kinnicutt. J. J. Berzelius. M. H. Klaproth. A. Laugier. E. Howard. C. A. Joy. T. Drown. R. H. Thurston. C. T. Jackson. B. Fernqvist. I. Domeyko. C. Winkler. G. Tschermak. C. Rammelsberg. Am. Jour. Sci., 1855 (2), xix. 161, 162. Proc. Cal. Acad. Sci., 1803, iii. 30-35. Jour. Chemie Physik, 1826, xlvi. 386. Jour. Chemie Physik, 1826, xlvi. 386. Juchner, Meteoriten, 1863, p. 139. \orrespondenz-Blatt Verei nes Kegensberg, 1851, v. 112. Clark, Metallic Meteorites, 1852, pp. 17-19. Akerman's Iron Man., Swe- den, 1876, p. xxxii. Edin. Phil. Jour., 1849, xlvii. 56, 57. Ann. Rep. Peabody Mus. Arch., 1884, iii. 381-384. Ann. Physik Chemie, 1834, xxxiii. 123-135. Diet. d'Hist. Nat., 1818, xxvi 259. Me'm. Mus. Hist. Nat., 1817, iii. 341-352. Diet, d' Hist. Nat., 1818, xxvi 259. Am.Jour.Sci.,1864(2),xxxvii 243-248. Communicated by M. Stan dish, Esq., 128 Broadway New York City. Bull. Mus. Comp. Zoul., 1881 vii. 185. Geol. Survey R. I., 1880, pp 52-54. Akerman's Iron Man., Swe- den, 1876, p. xxxii. Ann. Mines, 1864 (6), v. 431- 451. Nova Acta Leop. Acad., Hal le, 1878, xl. 333-282. Sitz. Wien. Akad., 1870, Ixi (2), 465-475. Mon. Berlin. Akad., 1870, pp 322-325. 6.52,6.91, 7.13 7.29 6.52 6.14 6.20 6.16 6.46 4.72-4.90 4.72 5.41 3.02 3.63 5.50 85.54 81.56 78.82 81.80 trace, trace. 0.12 (6.30 |3.00 13.CO 20.39 14.95 Silicates l'J.50 20.01 20.43 20.50 16.00 27.00 20.G89 20.85 22.87 23.00 21.25 23.34 26.787 29.41 33.24 87.35 91.50 60.27 45.20 69.16 44.50 44.021 58.50 4.09 6.05 0.01 0.01 8.95 52 v ' 85 8.50 7.03 686 68.20 52.50 48.298 4.35 3.56-4.05 45 44 27.60 43 FeS 14.10 FeS 7.226 FeS 7.40 22.20 10.417 , .62 88 12.40 v ' .45 14.32 3.53 7.417 3.51 9.93 9.99 15.30 6.30 3.872 5.55 10.64 13.10 5.55 4.10 0.70 0.188 0.72 3.82-3.88 5.64 4.29 Fe+Ni 3'J.OO Fe+Ni 50.406 Fe+Ni 32.50 4.12 4.61 ANALYSES OF METEORIC AND TERRESTRIAL ROCKS. XVII Pallasite. . Cad. MHO. Mn<). P.A. S. Cr,0 3 . Ni. Co. Cu. Sn. H./X Loss. Miscellaneous. Total. 204 p. 12 0.21 855 0.61 0.03 Analysis of .1 portion freest from silicates. 100.12 Ca. i it; 2.4'! P. 049 Cr. 9 17 044 008 Cl trace 99.08 1.10 460 810 300 Si 0.08 100.00 Mn. ii "ii 510 11 90 1.00 100.00 2.10 1.85 Cr. 0.50 260 100.50 2.00 1568 1.50 trace. 1.60 5.73 Insol. 0.20 Recalculated on the supposition that the 99.00 98.58 23 53 430 Insol. 0.15 silicates compose one third of the mass as they appear to do in the specimen teen by the present writer. Recalculated on Clark's supposition that 99.63 1 80 lO-'O 030 118 0019 1 40 the silicates compose one half Of the mass. 99.137 4.24 Analysis very imperfect 92.93 2280 0.05 P. . 633 0.22 trace. Recalculated on the supposition that the 99.94 silicates compose one half of the mass. 2307 022 5366 0.228 O.C 33 0.24 Mg 0.025, Mn 0.060, C 0.021, 101.27 1925 075 100 SnO = 0.09. Recalculated on the sup- position that the silicates comprise one half of the mass. 100.00 1500 520 050 520 300 113.10 1350 675 060 99.25 1.548 4278 0976 P. 115 2693 0477 ,V"IS 0838 004 SnO 2 0.1 8'J Mn 3.75, NiO+CoO = 0.07. 100.076 073 1645 99.69 O.C5 567 3 1)5 Zn 20. Mean of several analyses. 100.00 400 2 80 100.00 LOS 1> .;u 040 0127 0013 CnO 002 2 GO 99.06 2.31 3.66 Na < ) 0.22 Recalculated, but, owing to some doubts 100.95 0.60 6.31 N.-i.X I 0.4~8 0.018 regarding the original, the recalcula tiou is probably faulty. Fe,Ni 4 P P 2 P Fe.,Si Cr 2 O s -(-FeO 97.032 0.181 2228 0174 0.149, 0.274, 0.169, 0.323. Recalculated. 99.402 30.52 1 05 286 CrjOa+FeO = 0.50. 98.72 XVI 11 A CLASSIFIED LIST OF COMPLETE (BAUSCH) TABLE IV. Variety. Locality. Analyst. Publication. Sp. Gr. Si0 2 . M,0j. Fe. Fe,0 3 . FeO. CaO. iF. Pisani. Comptes Rendus, 1864, 26.08 0.90 830 21.60 1.85 Meteorite. Orgueil, France. lix. 132-135. S. Cloez. Comptes Rendus, 1864, 2.50 26.031 1.2498 .... 14.236 19.003 2.322 lix. 37-40. Meteorite. Murcia, Spain. S. Meunier. Comptes Rendus, 1868, 3.546 29.224 0.51 13.63 5.228 0.09 Ixvi. G3U-642. Meteorite. Noblcbo rough, Maine. J. W. Webster. Boston Jour. Phil., 1824, i. 386-389. 2.05 1 1 3.092 ) 29.50 4.70 14.90 .... trace. Meteorite. Cold Bokkeveld, f E. P. Harris. Sitz.Wien. Akad., 1859, 2.69 30.80 2.05 2.50 .... 29.94 1.70 South Africa. [ M. Faraday. xxxv. 5-12. Phil. Trans., 1839, pp. 2.94 28.90 5.22 33.22 1.64 83-87. f J. J. Berzelius. Ann. Physik Chemie, 1.94 31.22 2.36 .... 29.03 0.32 1 1834, xxxiii. 113-123. Meteorite. Alnis, Card, 1 Commission French Ann. Physik, 1806,xxiv. 1.7025 30.00 .... .... .... 38.00 France. Academy. 195-208. I L. J. Thenard. Buchner, Meteoriten, 21.00 .... .... .... 40.00 .... 1863, p. 20. Meteorite. Ornans, France. F. Pisani. Comptes Rendus, 1868, 3.599 31.23 4.32 4.12 .... 24.71 2.27 Ixvii. 66:5-1 ill."). Meteorite. Little Piney, Mis- C. U. Shepard. Am.Jour. Sci., 1840(1), 3.50 31.37 0.49 16.00 .... 17.25 .... souri. xxxix. 254, 255. Meteorite. Dacca, India. T. Hein. Sitz.Wien. Akad., 1866, 3.55 32.05 2.54 10.38 .... 23.88 1.12 liv. (2), 558-5(51. Saxonite. Gnadenfrei, Sile- Galle and Lasaulx. Mon. Berlin. Akad.,1879, 3.644 ) 3.712 J 32.11 1.60 25.16 14.88 2.01 sia. pp. 750-771. 3.785 ) Meteorite. Kernove, Morbi- F. Pisani. Comptes Rendus, 1869, 3.747 32.95 3.19 22.25 11.70 1.89 han, Frnnce. Ixviii. 1489-1491. Picrite. Bystry c, Teschen. J. Posch. Sitz.Wien. Akad., 1866, 33.01 15.83 2.75 7.62 13.61 liii. (I), 272. Meteorite. Klein -Wenden, C. Rammelsberg. Ann. Physik Chemie, 3.7006 33.03 3.75 23.90 .... 6.90 2.83 Germany. 1844, Ixii. 440-404. Meteorite. lleredia, Costa I. Domeyko. Analcs de la Universi- 33.10 1.25 24.59 16.97 1.19 Rica. daddeChile, 1859,xvi. 3-25-339. Meteorite. Petrowsk, Staw- ropol, Russia. H. Abich. Bull. Acad. St. Pc'ters- bourg, 1860, ii. 403- 348 ) 3.71 j 33.16 4.22 4.32 18.59 1.20 422, 433-439. Meteorite. Eichstadt, Bava- {A. Schwager. Siiz. Miinuhen Akiid., 3.70 33.31 2.31 0.74 ria. 1878, viii. 25-32. M.H. Klaproth. Mem. Acad. Berlin, 1803, 3.599 37.00 .... 19.00 16.50 .... .... pp. 42-45. *Buchnerite. Grosmija, Terek, Caucasus. Plohn. Min. Mitth., 1878, pp. 153-104. 3.45-3.55 ) 33.78 34.02 3.44 3.46 .... 4.78 28.86 29.07 3.22 3.24 Serpentine. Calagrande, Tus- A. Cossa. Rie. Chim. Roc. Italia, 2.992-3.025 33.863 7.562 .... 12.073 15.345 4.614 cany. 1881, p. 132. Meteorite. Saurette. Vau- A. Laugier. Ann. Mug. Hist. Nat., 3.4852 34.00 .... 38.03 .... .... .... cluse, France. 1842, iv. 249-257. Meteorite. Kaha, Hungary. F. Wohler. Siiz.Wien. Akad., 1858, ....>.. 34.24 5.38 2.88 .... 26.20 0.66 xxxiii. 205-209. Al,0 8 -1-FeO Meteorite. Meno.Alt-Strelitz, J. L. Smith. Am.Jour. Sci., 1876 (3), 3.65 34.75 16.54 "17 34 1.44 Mecklenburg. xii. 207-209. *Lherzolite. Zsadany, Banat. W. Pillitz. Zeit. Analyt. Chemie, 34.88 2.23 1823 11.09 3.45 1879, xviii. 58-68. Serpentine. Chester, Mass. E. Hitclicock. Geol. Mass., 1841, p. 160. 3491 10.27 Meteorite. Epinal, Vosges, L. N. Vauquclin. Ann.C4iimiePhys.,1822, 3.666 35.00 22.00 31.37 France. xxi. 324-328. Meteorite. Khettree, Rajpu- tana, India. D. Waldie. Jour. Asiat. Soc. Bengal, 1869, xxxviii. (2), pp. 3.743 ) 3.612 $ 35.17 1.77 18.79 11.16 2.37 252-258. Meteorite. Vernon Co., Wis- J. L. Smith. Am.Jnur. Sci., 1876 (3), 3.66 35.24 1.67 15.72 .... 15.54 1.41 consin. xii. 207-20'.!. Meteorite. Borkut, Hungary. J. Nuricsany. Sitz. Wion. Akad., 185G, 5.242 35.28 2.74 27.03 4.71 1.95 xx. 398-406. *Dunite. Chassigny, Haute A. A. Damour. Comptes Rendus, 1862, 3.57 35.30 .... .... 26.70 .... Marne, France. Iv. 591. * The prefixed asterisk indicates that the specimen is a meteorite. ANALYSES OF METEORIC AND TERRESTRIAL ROCKS. XIX Peridotite. KgO. MnO. -NaX). K.U. Cr 4 a . Ni. Co. Cu. Sn. P. S. HjO. Miscellaneous. Total. 17.00 8.0711 24.80 &ao 19.20 B.31 11.00 9.00 24.40 25.88 22.90 17.03 23.68 7.28 23.04 20.39 29.24 18.86 21.50 18.66 23.72 18.092 14.50 B.89 lO.lfi 41.!ll 4.25 23.80 82.05 ::i.7i; 0.30 1.9302 2.20 1.323 0.35 0.19 0.32G5 trace. Cr 2 O 3 +FeO " 0.41) ftJX oases CrjOj-rFeO " 0.-J2 4.00 0.70 0.70 C.,O a +FeO 0.63 Cr 2 8 2.00 1.00 FeO+Cr.,O 3 0.40" NiO+CoO 2.20 NiO 2.0057 1.36 2.30 mo 1.30 0.82 NiO 1.88 Ni 2.00 NiO 3.60 NiO 2.88 Ni, <"r, Co * 428 1.63 3.92 1.55 5.75 H.,SO 4 = 1.64, II ,SO, = 0.53, Cl = 0.08, H/) -|- organic matter = 10.81. II_,S( ) 4 = 2.3345, C! = 0.0770. "Organic mutter = 0.41. Am- mnia=0.1042. H. 1 O=7.812. FeS = 20.52. 100.00 09.472 99.758 98.50 98.79 100.44 CoO 0.0904 4.0460 7.812 18.30 0.97 026 Mn. B.OO 2.00 trace. trace. 0.07 trace, trace. 0.03 .... trace. 3.38 4.24 6.50 C = 1.07. Bituminous matter = 0.25. 1. trace. a Insol. = 8.09. C = 2.50. IL,O+loss = 9.60. C = 2.50. HoO+loss = 18.60. Fe, Xi = 1.85. S- t -P?+loss = 4.73. NiO = 0.80. 80 ' 100.00 100.00 99.42 100.00 98.47 90.85 100.77 08.70 100.01 00.87 90.24 99.15 10000 100.00 100.07 99.913 100.00 98.50 98.99 109.79 100.00 90.87 101.31 100.51 98.40 9M 350 0. trace. 1.50 0.70 ">'> .... trace. trace. 2.69 .... 0.07 trace. 0.11 .... 0.05 PA truce. 0.78 1.87 2 15 .... 0.57 O 2 3 +FeO trace. 1. 0.59 0.28 0.88 1.40 1.04 tl 1.81 0.38 0.04 0.60 0.40 4.23 CO. 2 = 11.07, LljO = trace. Rock altered. 0.62 2.37 1.51 NiO 3.81 0.94 1.50 .... 0.05 0.08 0.02 2.09 Recalculated. C = trace. Fe+P = 24.04. Loss, etc. = 4.60. FcS = 5.37, C0. 2 = 0.08. Fresh portion. CO., = 0.08. Kxterior portion. TiO. 2 = 0.080. Ignition ;= 5.808. HoO+loss = 3.31. FeS = 3.55, C = 0.68. FeS = 4 24. Recalculated. C = 0.21, Mn = 1.64, Cr 2 O 3 + FeO = 0.56. Loss = 0.40. CaO+K./> = 1.25. Cr = 0.10. Loss = 2.00. FeS = 4.60. Recalculated. Xi + Mn = 0.78. Recalculated. Chromite+Pyroxene = 3.77. 0.15 .... .... SnO. 1.10" .... 1.60 1.42 .... trace. MM. 0.83 0.05 trace. 0.63 0.03 030 0.30 0.17 0.17 1-f 0.33 1.37 1.36 2.77 ">00 0.94 0.31 0.30 Cr,O,+FeO 0.89 trace. 0.02 trace. 0.01 trace. 03 trace, trace. 0.45 2.64 9.45 4.31 0.94 0.25 0.40 NiO 0.60 1.20 128 14 225 .... 0.87 1.01 trace. 0.21 0.07 4 trace. 08~ 0.12 trace. 0.03 1.70 0.89 0.45 IM 0.60 0.60 Cr.o. + FeO " 0.04 0.76 t 1'robnlilj a Misprint for 3.05. liuclmer, Meteoriten, 1863, p. 40. XX A CLASSIFIED LIST OF COMPLETE (BAUSCH) TABLE IV. Variety. Locality. Analyst. Publication. Sp. Gr. SiO. 2 . A1 2 3 . F, Fe 2 3 . FeO. CaO. *Dunite. Chassigny, Haute L. N. Vauquelin. Ann.CliimiePhys.,]816, 33.00 31.00 Marne, France. i. 4!)-54. Meteorite. Warrenton, Mis- J. L. Smith. Am. Jour. Sci., 1877 (3), 3.47 35.63 0.13 1.78 30.44 1.41 souri. xiv. 222-224. F. Crook. Chem. Const. Met. 3.50 35.047 2.307 8.00 .... 34193 1.776 Stones, ]>p. 21-26. Meteorite. Ensisheim.Elsass, C. Barthold. Jour. Phvsique 1800 3.233 4200 17.00 20.00 2.00 Germany. 1. l<;!M'7 2.61 Gesell.,1868,ix.35-40. Lherzolite. Pultusk, Poland. C. Rammelsberg. MOD. Berlin. Akad., 1870, 35.85 1.96 15.55 3.85 12.12 1.56 pp. 448-452. G. vom Rath. Neues Jalir. Min., 1869, 3.537-3.782 41.54 1.17 11.57 * . 14.04 0.28 pp. 80-82. Meteorite. MudJoor, India. F. Crook. Chem. Const. Met. 30.256 20.28 10.091 17.97 0.81 Stones, pp 33-36. f F. Stromeyer. Ann. Plivsik, 1812, xlii. 3.61 36.32 1.004 24.415 .... 5574 1.C22 105-110. Meteorite. Erxleben,Prussia. < C. F. Bucholz. Jour. Chemie Pliysik, 3.5904 30.625 225 13.75 .... .... 0.75 1813, vii. 143-174. M. II. Klaproth. Beitriige Mineralkorper, 360 ) 35.50 1.25 31.00 0.50 1810, vi. 303-300. 3.64 ) A. Kuhlberg. Arcliiv Nat. Liv-, Ehst-, 3.7:33 ) 36324 2.650 10.324 .... 13.020 trace. Kurlands, 1867(1 ),iv. 3.721 f 30.582 2.385 17.572 .... 12.386 trace. Meteorite. Lixna, Russia. T. von Grotthus. 1-32. Ann. Plivsik Chemie, 3.756 , 33.20 1.30 26.00 22.00 0.50 1852, Ix'xxv. 577. A. Laugier. Ann.ChimiePhys.,1824, 3.G608 34.00 1.00 .... .... 40.00 0.50 xxv. 219-221. f J. L. Smith. Am. Jour. Sci., 1875 (3), 3.57 30.34 0.63 11.16 22.28 .... Saxonite. Iowa Co., Iowa. x. 302, 363. [ Giimbel and Sehwa- Sitz. Miinc-hen Akad., 3.75 36.08 1.18 10.27 .... 22.39 1.39 ger. 1875, v. 313-3SO. Meteorite. Nulles, Tarrago- L. de la Escosura. Phil. Mag, 1862 (4), 3.818 30.43 0.84 22.50 13.55 ... .... na, Spain. xxiv. 530-538. Meteorite. Ohaba, Transyl- F. Bukeisen. Sitz. Wien Akad., 1858, 3.11 30.60 0.28 21.40 .... 1.75 trace. vania. xxx i. 70-84. Meteorite!?) Mainz, Hesse. F. Seelheim. Jahrh. Vereins Natur. 3.26 36.70 13.49 .... ... 31.89 trace. Nassau, 1857, xii. 405-410. Meteorite. Xanjemoy, Mary- G. Chilton. Am. Jour. Sci., 1825(1), 3.0G 36.72 0.10 .... 00.30 090 land. x. 131-135. Meteorite. Hizen, Japan. T. Shimidzn. Trans. Asiat. Soc.Japan, 3.62 30.75 1.89 15.35 .... 8.84 1.94 1882, x. 1119-203. {G. Lindstrom. Ann. Phvsik Chemie, 3.697 36.83 2.38 20.08 .... 10.85 2.38 Meteorite. Hessle, Sweden. 1870, cxli. 205-224. A. E. Nordenskjold. Ann Pliysik Chemie, 1870, cxli. 205-224. f 3 0711 i 4.004 } ( 4.048 J 36.75 37.08 2.00 1.11 1642 16.29 .... 13.36 13.49 1 50 2.06 Tufa. Chnntonnay, Ven- C. Rammelsberg. Zeit. Pent. geol. Gesell., 3.44-3.49 36.89 2.47 9.77 .... 15.99 1.38 dee, France. 1870, xxii. 889-892. Meteorite. Blansko, Moravia. J. J. Berzelius. Ann. Physik Chemie, 3.40 37.077 2.386 16.089 .... 14.945 1.248 ls;!4, xxxiii. 8-25; 1805, cxxiv. 213-234. Serpentine. Duporth, Corn- f J. H. Collins. Min. Mag., 1877, i. 224. 2.G4 37.09 19.90 .... 15.54 2.02 trace. wall, England. 1 J.A.Phillips. Min. Mag., 1877, i. 224. 286 35.74 12.23 4.68 13.84 trace. * The prefixed asterisk indicates that the specimen is a meteorite. ANALYSES OF METEORIC AXD TERRESTRIAL ROCKS. xxi Continued. MgO. MnO. NaA KA CrA. Ki. Co. Cu. Sn. P. S. HA Miscellaneous. Total. Si.OO 2,1.7 t 13.13 14.00 18.00 35.03 23.16 2:1.77: 1'7 171 84.00 23.47 MM 26.73 27.483 23.584 23.0875 26.50 21. -Hi 10.80 17.00 19.70 18.21 19.47 23.45 16.12 6.20 MJM 8&21 2(5.06 24.08 86.16 15.90 2213 2.00 0.00 0.409 98.90 100.53 99.504 97.00 105.30 100.04 100.00 99.999 100.00 90.91 99.97 09.39 9901 90.318 99.642 0.210 0.24 0.370 0.223 0.21 1.23 0.01 NiO 1.17, CoO 0.24, FeS 1.013 2.05 2.00 = 3.47. Recalculated. 2.40 3.50 trace. 2.27 2.364 2.184 0.11 0.25 trace. 0.002 0.87 0.40 trace. 0.225 CrA+FeO 0.92 1.30 CryoJ+Veb 0.29 0.158 0.240 CuO i'A o.oa 0.01 0.011 12.04 6.61 OA+FeO = 1.37. Cl = 004, NiO = 0.20, PA = 0.30. Loss = 0.84. Grapl>ite+SnO 2 +loss =0.146 CO. 2 = 17.05, FeO+Mn+etc. = 3.40. 0. 0.02 1.637 0.26 77 0.15 0.44 0.325 1.01 0.73 1.513 0.17 0.105 trace. .... 0.49 0.705 0.8125 0.25 0.025 0.034 0.60 0.95 1.34 0.33 0.741 0.39 0.285 1.69 2.21 0.65 1.162 1.579 0.60 0.25 1.725 1.090 2.00 1.50 1.30 2.05 1.43 1.80 NiO 2.08 ino 4.10 1 77 Recalculated. Insol. = 0.04. Recalculated. trace 0.87 1 543 .... 2952 FeS = 21.625. S+loss = 3.76. Mn = 0.547. Mn = 0.302. Mn = trace. Mn = trace. U,0 = trace, FeS = 5.82. Re- calculated. FeS = 525. Recalculated. FeS = 2.34, Insol. = 0.79. FeS = 13.14. Fe, Ki = 2.13, FeS = 3.80. Recalculated. NiO = 0.30, FeS = 5.91, Mn = 0.18. C = trace, Cl = 0.04. C = 0.52. C = 0.85. 10000 100.00 99.827 107.974 100.20 101.80 98.71 99.85 98.20 100.11 100.05 109.66 99.01 100.84 100.00 100.00 97.09 99.243 99.31 100.04 0.680 0.759 trace, trace. 1.00 Cr/M-FeO 0.759 bass 0.90 CrA 1.00 0.120 0.163 2.204 2.052 3.50 6.80 .... 0.08 trace. .... .... 0.25 0.80 0.15 Mn. trace. 1.40 0.82 trace. 0.57 0.49 Cr 2 O,+FeO 0.59 CrA+ F eO 0.56 0.46 V ' 98 1.21 trace l',o. 0.00 254 1.51 .... trace trace 0.51 0.42 0.97 0.-J4 1.03 0.16 CrJi.+FeO 0.01 0.07 PA 0.34 0.16 trace trace 1.88 0.37 trace. 2 24 .... 1. 2.15 108 2.33 1.16 0.8CO 5 0.02 trace, (race. 0.15 CuO-f-SnO 0.02 0.01 0.02 0.27 0.489 trace. 0.98 2.11 n.o; CfjO .+FeO 0.616 1. 0.740 trace. 0.25 11 0.187 trace. trace. 0.00 0.( v "^ 178 ".-I 0.18 0.050 8.65 1001 XiO = 0.207. Analysis reenlcu lated by Von Uciclienbacli. TiO.j = trace. XX11 A CLASSIFIED LIST OF COMPLETE (BAUSCH) TABLE IV. Variety. Locality. Analyst. Publication. Sp. Gr. SiO-j. AL0 3 . Fe. Fe. 2 3 . FeO. CaO. Picrite (Pa- Fichtelgebirge, II. Loretz. Grumbel's Die palaoli- 37.12 4.96 8.92 7.62 0.14 Ueopicrite). Bavaria. thisclien Eruptivge- steine des Fichtelge- birges, 1874, p 40. . r / Serpentine. Reichenstein, G. L. Ulex. Zeit. Deut. geol.Gesell., 37.10 1.43 10.60 Silesia. 1867, xix. 243. Lherzolite. Presque Isle, 3. D. Whitney. Am.Jour. Sci., 1859(2), 37.25 .... .... 6.75 14.14 Michigan. xxviii. 18. Meteorite. Adare, Limerick R. Apjohn. Jour. Chem. Soc., 1874 3.621-4.23 37.26 2.03 16.24 .... 8.95 3.61 Co., Ireland. (2), xii. 104-106. Meteorite. Alessandria, Pied- G. Missaghi. Ann. Physik Chemie, 3.815 37.403 8.65 19.37 ... 12.831 3.144 mont. 1803, cxviii. 361-303. Olivinfels. Kalohelmen, Nor- Ilanan. Verh. Geol. Reich.,1807, 37.42 0.10 8.88 way. pp. 71, 72. *Saxonite. GJopalpur, India. A. Exner. Min. Mitth., 1872 pp. 37.44 2.52 20.96 11.94 1.60 41-48. Saxonite. Tourinnes-la- F. Pisani. Comptes Rendus, 1864, 3.525 37.47 3.65 11.05 13.89 2.61 Grosse, Lou- Iviii. 169-171. vain, Belgium. Serpentine. Lynnfielcl, Massa- C. T. Jackson. Proc. Bost. Soc. Nat. ........ 37.50 .... * 2.50 ... chusetts. Hist, 1850, v. 318. Meteorite. Kakova, Hun- E. P. Harris. Chem. Const. Meteor- 3.384 37.02 2.25 7.11 22.47 0.69 gary. ites, 1859, pp. 22-34. Meteorite. Bandung, Java. C. L. Vlaanderen. Comptes Rendus, 1872, 3.619 37.65 3.96 4.96 4.30 16.87 1.06 Ixxv. 1676-1678. Meteorite. Dutulrum, Tippe S. Haughton. Proc. Roy. Soc., 18G6, 3.066-3.57 37.80 0.85 19.57 .... 7.92 1.32 raryCo., Ireland. xv. 214-217. f M. H. Klaproth. Ann. Physik, 1809, 3.70 38.00 1.00 17.60 25.00 ... 0.75 Meteorite. Smolensk, Russia. \ xxxiii. 210, 211. [j. Scheerer. Ann. Physik, 1808,xxix. 3.0046 39.00 .... 17.76 17.60 214. *Tufa. Orvinio, Italy. L. Sipiicz. Sitz. Wien. Akad., 1875, ( 3.675 38.01 2.22 22.34 .... 6.55 2.33 Ixx. (1),4G4. \ 3.600 36.82 2.31 22.11 9.41 2.31 Meteorite. Pohlitz, Reuss, F. Stromeyer. Jonr. Chemie Physik, 3.4938 38.0574 3.4688 17.4896 .... 4.8959 .... Germany. 1810, xxvi. 251, 252. Meteorite. Castalia,Nash Co., J. L. Smith. Am. Jour. Sci., 1875 (3), 2.601t 38.06 2.12 14.02 ... 13.10 .... North Carolina. x. 147, 148. Serpentine. Stanford, Mass. E. Hitchcock. Geol. Mass., 1841, p. ICO. 38.09 6.75 Meteorite. Saint Mesmin, F. Pisani. Comptes Rendus, 1866, 38.10 3.00 4.94 17.21 1.09 Aube, France. Ixii. 1326. Meteorite. jhateau-Renard, A. Dufre'noy. Comptes Rendus, 1841. 3.56 38.13 3.82 7.70 .... 29.44 0.14 France. xiii. 47-53. f A. Schwager. Sitz. MUnchen Akad. 3.4566 38.14 2.51 25.70 2.27 Meteorite. Mauerkirchen, -j F. Crook. 1878, viii. 16-24. Chem. Const. Meteoric 41.532 1.705 23.32 2.115 Bavaria. 1 Stones, pp. 26-30. [ Imliof. Sitz. Miinchen Akad., 3.452 25.40 .... 2.33 40.24 .... .... 1878, viii. 17. Serpentine. Varzi, Italy. A. Cossa. Ric. Chin). Roc. Italia, 38.22 trace. 14.05 trace. 1881. pp. 162-164. Serpentine. [vynance Cove, S. Ilaughton. Phil. Mag., 1855 (4), x. 38.29 13.50 Cornwall, Eng. 254. Meteorite. Charsonville, Loi- L. N. Vauquelin. Ann. Mus. Hist. Nat., 3.712 38.40 3.60 25.80 .... .... 4.20 ret, France. 1811, xvii. 1-15. 3.57-3.65 Meteorite. Drake's Creek, f E. II. Baumhauer Ann. Plivsik. Chemie, 3.469 38.503 4.807 12.816 .... 10.029 0.70 Simmer Co., | 1845, Ixvi, 408-503. Tennessee. [ H. Seybert. Am.Jour. Sci., 1830(1), 3.484-3.487 40.00 2.466 12.00 12.20 .... xvii. 326-328. Meteorite. Aukoma (Pillits- Grewingk and Archiv Nat. Liv-, Ehst-, 3.647 38.593 2.491 25.667 .... 2.519 0.48 fer), Livland, Schmidt. Knrlands, 1804, iii. Russia. 421-554. *Saxonite. Waconda.Kansas. J. L. Smith. Am.Jour. Sci., 1877 (3), 3.40-3.60 38.61 1.09 4.60 22.81 trace. xiii. 211-213. Serpentine. Monteferrato, A. Cossa. Ric. Chim. Roc. Italia, 2.55 38.70 0.58 .... 3.19 7.20 trace. Italy. 1881, pp. 148, 140. Meteorite. Richmond, Vir- C. Rammelsberg. Mon. Berlin. Akad., 3.3713 38.71 2.17 6.45 .... 18.17 2.53 ginia. 1870, pp. 453-457. Meteorite. Ausso n, Haute Ga- f A. A. Damour. Comptes Rendus, 1859, 3.51-3.57 38.72 1.85 8.63 16.93 0.80 ronne, France. JE. P. Harris. xlix. ;il-:;<>. Chem. Const. Meteor- 3.50 38.46 2.25 7.13 18.00 trace. ites, 1859, pp. 44-51. The prefixed asterisk indicates that the specimen is a meteorite. ANALYSES OF METEORIC AND TERRESTRIAL EOCKS. xxin Continued. MgO. MnO. Na/>. K/>. CrA- Ni. Co. Cn. Sn. P. S. HoO. Miscellaneous. Total. ::I;LM ll.lTii <&22 tt.72 24.10 41.00 21.74 13.24 1'::.:::; 14.25 20.00 24.11 il.60 29.9300 H.48 40.19 2.1.IU 17.07 21.7:: 24.202 28.75 32.83 34.24 18.60 88.833 j:;.r,r,ii 25.15 H H 27.:M> 82.68 26.06 0.40 0.40 0.49 !'/> 0.10 5.04 12.15 10.89 TiO 2 = 0.40, CCX, = 0.09. FeA = 2.70. Analysis of soluble portion only. FeS = 0.54, V = trace. Re- calculated. 98.00 100.34 98.80 90.19 08.327 99.73 98.90 99.72 100.00 101.13 98.33 98.99 100.00 100.00 101.42 100.96 99.1802 98.92 100.00 99.00 99.97 100.75 98.430 100.00 99.76 98.12 98.70 100.00 95.931 100.00 98.38 99.70 98.16 99.05 98.01 1 10 &BO Mil tract'. (U7 0.20 trace. 0.79 0.12 in' -i-FeO "1.75 0.845 2.73 1.077 NiO OJ8S 1.80 1.30 0.10 trace. 3.831 Ignition = 4.71. 0.62 0.21 trace. Cr 2 O 3 +FeO 0.71 0.10 1 74 017 2.21 2.: A 15.CO CaC0 3 = 4.00. Graphite = 0.14. Recalculated. 0.42 0.16 1.76 2.11 0.96 061 1.07 0.50 Cr. 2 O s +FeO 0.07 (>.,(), +FeO 4.41 Cr.jO 8 +FeO 1.50 1.24 1.03 1.03 0.40 1.25 2.15 3.04 1.3057 1.12 0.10 0.14 trace. .... 0.01 trace. 2 13 FeS = 4.05. Recalculated. Loss, etc. = 3.00. Loss, etc. = 4.50. 1.1 407 1.46 0.90 0.55 0.31 0.20 trace. 0.1298 1.94 2.04 2.6957 0.46 - 0.06 trace. .... trace. 14.77 Li/) = trace. Loss = 0. 20. FeS = 2.09. .... Crj6 8 +FeO 2.18 0.89 Cr a O.,+FeO 0,725 8. 0.80 1.00 0.242 13 0.27 0.48 0.145 1.65 0.39 209 0.705 0.14 .... Fe+Ni = 0.30. Fe+Xi= 3.745. S+loss = 2.08. 1.20 trace. 1405 1209 MM 0.00 2.31 0.594 0.025 1.50 1.374 0.833 0487 0.00 1.405 NIO 2.100 1.878 0.04 MO trace. 1.18 0.00 1.02 5.00 1.804 2433 0.102 1 V O.C s <55 .... .... CuO+SnO 2 +KiO = 2.528. 0.018 Mn 0.46 0.341 1.07 0.24 trace. trace. 0.10 0.013 trace. 3.492 Graphite+TiO^+Ioss =0.115. Li./) = trace, FeS = 3.85. Re- calculated. Ignition = 13.23. trace. .... 0.30 trace. 0.34 0.57 0.10 0.11 0.18 Cr.,O a +Fc<> Cr.,0, 0.78 p+Fe+Ni, etc. = 2.00, FeS = 374. Keualriilalcd. FeS =2.51. Recalculated. V 0.00 .... .... trace. 2.10 t Probably a misprint for 3.001. XXIV A CLASSIFIED LIST OF COMPLETE (BAUSCH) TABLE IV. Variety. Locality. Analyst. Publication. Sp. Gr. SiO 2 . Al,0., Fe. Fe. 2 3 . FeO. CaO. Meteorite. Ausson, Haute Ga- Filhol and Leyme- Comptes Rendus, 1859, 3.30 60.28 1.82 8.30 2.32 15.38 0.55 ronne, France. rie. xlviii. 193-198. Fieri te. Schiinau, Neutit- F. E. Szameit. Sitz. Wien. Acad., 1800, 3.029 38.72 10.19 6.30 6.14 10.37 schein, Moravia. liii. (1),260. Serpentine. Neurode, Silesia. G. vom Rath. Ann. 1'hvsik Chemie, 2.912 38.78 3.06 .... 14.19 4.51 1855, cxv. 553. Serpentine. Kiver Oisain, Ti- Pufahl. Saminl. (ieol. Mus. Lei- 38.81 1.14 6.80 2.10 0.32 mor. den, 1884, ii. 109. Serpentine. Lizard. Cornwall, England. J. A. Phillips. Phil. Mag., 1871 (4), xli. 101. 2.59 j 38.86 38.58 2.95 3.06 1.86 1.95 5.04 6.10 trace, trace. Meteorite. Rakowska, Tula, P. Grigoriew. Zeit. Dent. geol. Oesell., 3.582 38.87 2.66 6.67 1:5.44 2.36 Russia. 1880, xxxii. 417-420. Dunite. Sum) more. Nor- W. C. Brogger. Neues Jalir. Min., 1880, 3.32 38.87 8.45 0.99 way. ii. 187-192. Picrite. Soldo", Neutit- G. Tschermak. Sitz. Wien. Akad., 1806, 2.901 38.90 10.30 .. 4.90 7.00 6.00 schein, Moravia. liii. (1), 263; 1807, Ivi. 274, 276. Serpentine. 1'rato, Italy. A. Cossa. Ric. Cliim. Roc. Italia, 2.57-2.69 38.94 .... 1.18 8.25 trace. 1881, pp. 151, 152. . f C. Rammelsberg. Mon. Berlin. Akad.,1870, 38.90 2.00 13.51 14.52 1.18 Meteorite. Linn Co., Iowa. pp. 457-45U. 1 C. U. Shepard. Am., lour. Sci., 1848 (2), 62.34 8.98 20.42 vi. 403-405. Meteorite. Cynthiana, Ken- J. L. Smith. Am. Jour. Sci., 1877 (3), 3.41 38.99 0.22 5.36 .... 19.73 2.20 tucky. xiv. 224-227. *Buchnerite. Alfianrllo, Bres- H. von Foullon. Sitz. Wien. Akad., 1883, 39.14 0.93 11.81 17.42 1.96 cia, Italy. Ixxxviii. (1),433. Meteorite. Sc'tif, Algeria. S. Meunier. Cornples Hendus, 1808, 3.595 39.20 1.64 14.18 2.06 Ixvi. 513-519. Serpentine. Rio Marina, Ell>a. A. Cossa. Uic. Chim. Roc. Italia, 2.59 39.21 trace. .... 7.87 2.63 trace. 1881, pp. 134. 135. Meteorite. Utreclit, Holland. E. H. Baumhauer. Ann. Pliysik Chemie, 3.57-3.05 39.301 2.252 11.068 .... 15.290 1.48 1845, Ixvi. 405-498. Serpentine. Longone, Elba. A. Cossa. Ric. Chim. Roe. Italia, 2.G1 39.38 trace. .... 8.26 3.67 trace. 1881, pp. 130, 137. Meteorite. Parnallee, India. E. Pfeitfer. Sitz. Wien. Akad., 1863, 3.115 39.408 2.573 9.83 .... 15.283 0.56 xlvii. (2), 400-403. Serpentine. Rio Alto, Elba. A. Cossa. Rie. Chim. Roc. Italia, 2.01 39.68 ... * > . 7.65 4.13 trace. 1881, pp. 135. 13(i. Dunite. Karlstatten, Aus- Kouya. Sitz. Wien. Akad., 1867, 3.011 39.61 1.68 8.42 trace. tria. Ivi. 277. Meteorite. Honolulu, Hawaii, Sandwich Isls. A. Kuhlberg. Archiv Nat. Liv , Ehst-, Kurlnn.ls, 1867 (1), 3.5309 I 3.3964 ) 39.65 1.93 6.45 19.15 iv. 1-32. Meteorite. Villeneuve, Ales- Bertolio. Comptes Rendus, 1808, 3.29 39.601 0.416 20.70 .... 12.234 0.878 sandria, Italy. Ixvii. 322-320. Meteorite. Girgcnti, Sicily. G. vom Rath. Ann. Physik Chemie, 3.594 39.72 "1.44 10.40 .... 16.47 1.70 1869,cxxxviii.541-545. Serpentine. Valle Tonrnnn- A. Cossa. Ric. Cliim. Roc. Italia, 2.80 39.76 .... 5.11 6.37 .... elie, Piedmont. 1881. p. 120. Serpentine. MontemezEano, A. Cossa. Ric. Chim. Roc. Italia, 2.56; 39.77 trace. 1.76 8.48 trace. Italy. 1881. p. 150. Olivinfels. Krauhat, Steier- H. Wieser. Min. Mitth., 1872, p. 79. 2.889 39.87 0.9 .... 9.76 0.64 0.44 inark. Serpentine. Portoferraio, A. Cossa. Ric. Chim. Roc. Italia, 2.53 39.932 trace. .... 6.899 3.75 .... Elba. 1881, pp. 137, 138. Meteorite. Swajalm, Kur- land, Russia. A. Kuhlberg. Archiv Nat. Liv-, Ehst-. Kurlanils,18G7(l),iv. 3.4341 | 39.97 40.414 3.06 3.798 6.15 8.322 ia45 15.424 1-32. Meteorite. Xerft, Russia. A. Kuhlberg. Ann. Pliysik Chemie, 40.00 3.52 8.36 15.98 0.05 18(19, rxxxvi. 448,441). Meteorite. Pohgel, Kurland. Russia. A. Kuhlberg. Archiv Nat. Liv-, Ehst-, Kurlands, 1867 (1), 3.555 j 40.05 39.556 3.94 3.299 10.15 8.835 14.11 14.902 trace. 0.185 iv. 1-32. Serpentine Ballinahinch J. A. Galbraith. Jour. Ot'ol Soc. Dublin, 40.12 trace. 3.47 trace. Quarry, Conne- 1852, v. 138. mara, Ireland. Meteorite. Schonenber^, lia- C. W. Giimbel. Sitz. Miinchen Akad., 40.13 6.57 13.77 17.12 2.31 varia. 1878, viii. 40-40. Meteorite. Sokol IJanja, Ser- S. M. Losanitch. Beriehte Chem. Gesell. 3.502 40.14 . . 5.82 .... 25.54 .... via. Berlin, 1878, xi.9U-98. * The prefixed asterisk indicates that the specimen is a meteorite. ANALYSES OF METEORIC AND TERRESTRIAL ROCKS. XXV 'nued. KgO. Mud. Na.O. KM CrjOj. Ni. Co. Cu. Sn. P. S. H.p. Miscellaneous. Total. 1(171 2.10 0.72 1.82 Recalculated. no., = trace, CO., = 2.93, Or- ganic material = truce. Ignition = 7.74. Ti0. 2 = 0.16. 99.73 100.27 99.55 99.92 1(IO.:!0 D'J.'.I? 1R60 8101 MJU 24.GO 61.80 KXSO 26.05 175 2G.5G 25.01 25.08 36.92 24.066 Kuoa 22.81U 36.37 42.2'.l 24.51 14.778 24.61 38.10 :;:,;:; 40.09 24.!>1 96.481 25.59 84.85 10.681 40.04 10.81 2578 1 50 167 3.96 O.'JO trace. tttliv. trace. 0.24 0.12 0.11 0.12 0.77 0.78 2.04 049 trace. 0.33 O.SO 0.37 0.02 0.08 0.08 Crf>s+yM 0.81 Cu() 0.04 1U), o.oa 14.87 15.52 15.52 HtO 0.88 O.-.M 1.43 0.32 0.12 Mn = trace, C = 0.13, FeS = 0.10. 100.29 99.10 99.84 100.00 98.21 101.77 100.42 99.84 99.44 100.00 99.78 100.00 100.45 97.92 98.09 100.00 98.45 99.72 09.71 100.11 100.036 98.30 B&368 99.40 !* 98.811 98.99 100.00 100.21 1.30 0.80 4.50 CO. 2 =1.80. Ignition = 13.90. Recalculated. FeS = 6.00. Recalculated. FeS = 5.60. Becalculated. 0.29 mo truce. 1.08 1.46 0.60 1.09 0.38 trace. 2.32 0. 0.49 075 20 010 0.15 0.07 2.71 0.12 0.27 0.650 trace. CraOa+FeO trace. trace. Fe+Ni = 8.32, FeS = 8.04. Ignition = 12.64. MnO + NiO = 0.009, CuO + SnO., = 0.2.")li. TiOi = trace, Ignition = 12.85. CoO., = 0.00, Zn = trace, NiO ="0.724. Ignition = 12.72. trace. trace. 0.54 trace.'. 1.395 1.907 001 0.152 0.547 0.02 26 0.005 1.897 1.24 2 O.C 0.904 0.00 trace. trace. 0.10 2.712 0.684 589 Mn. 0.21 trace. 0.88" trace. CrjOj+FeO 1.35 0.088 Cr-Og+FeO 1.00 trace. 0.27 0.04 I'.O, O.iV.17 2.29 0.503 2.06 1.0 NiO 6.371 1.05 NiO trace. .... trace. 996 Cl = 0.105, Loss = 0.537. Recalculated. 4.1 51 Ignition = 12.10. trace, trace. trace. .0.045 0.03 0.04 0.021 1.28 NiO 0.00 648 0.183 Cr.,O,-(-FeO " o.i;j 0.478 Cr./) ;1 +FeO 0.05 Cr.,O,-l-FeO 0.68 0.848 TiO,= trace, Ignition=13.047 Mn = 0.05. Mn = 08. Mn = 0.10. Mn = 0.09. Mn = 0.107. CO., = 2.00. 0.84 0.668 1.C5 0.766 0.030 0.09 0.038 0.08 0.123 0.072 .... 0.01 0.005 0.05 0.06 (.0.-|! 1.88 1.293 2.02 2.35 2.M6 13.3<; 1.4t U 1.32 .5 trace. .... rs 0.9* 1 0.12 2.20 0.26 0.73 0.06 0.60 0.04 1.47 0.92 0.30 trace. 1.93 1.40 0.07 .... Recalculated. XXVI A CLASSIFIED LIST OF COMPLETE (BAUSCH) TABLE IV. Variety. Locality. Analyst. Publication. Sp. Gr. Si0. 2 . A1A- Fe. Fe. 2 3 . FeO. CaO. Meteorite. Bachmut, Jeka- therinoslaw, f A. Kublberg. 1 iF. T. Giese. Arcbiv Nat. Liv-, Ebst-, Kurlands, 18(57 (1), iv. 1-32. Ann. Pbysik, 1815, 1. 3.563 | 3.4235 40.209 38.971 44.00 2.884 2.6W 3.00 8.105 8.928 21.00 .... 22.374 16.288 0.089 trace. Russia. F. Wohler. 117, 118. Sitz. Wien. Akad. 1802 3371 2.78 12.00 14.17 1 "1 *Buchnerite. Tiescliitz, Mora- via. Fohrenbiihl, Ba- J. Habermann. G. Schulze. xlvi. (2), M02-306. Denks. Wien. Akad., 1879, xxxix. 187-201. Zeit. Deut. geol. Gesell., 3.59 40.23 40.30 1.93 1.30 10.26 1.35 19.48 8.50 1.54 trace. varia. T. S. Hunt. 1883, xxxv. 451. Am. Jour Sci.j 1858 2.597 4030 7.02 *Saxonite. Picrite. Serpentine. Serpentine. Goalpara, India. Diltenburg, Nas- sau, leiligenblut, Ca- rintliia. Lizard Point, N. Teclu. G. Angelbis. R. v. Drasehe. T. S. Hunt. xxv. 219. Sitz. Wien. Akad., 1870, Ixii. (2), 852-864. [naug. Dissert., Bonn, 1877, p. 9. Min. Mitth., 1871, p. '8. Am. Jour. Sci., 1858, 3.444 3.108 2.79 40.36 40.37 40.39 40.40 9.86 1.68 0.65 8.49 4.76 9.98 13.32 8.34 3.32 0.60 4.74 4.78 Serpentine. Serpentine. Meteorite. Serpentine. Serpentine. Cornwall. ?avaro,Piedmont. ..evanto, Italy. )oroninsk, Sibe- ria. Fahlun, Sweden. Sprechenstein, A. Cossa. C. T. Heycock. J. Sclieerer. {R. F. Marchand. J. L. Jordan. E. Hussak. xxvi. 239. Sic. Cbim. Roc. Italia, 1881, pp. 125-127. Geol. Mag., 187'J (2), vi. 307. Mem. Acad. St. Pe'ters- bourg, 1813-14, vi., Hist., p. 46. Neues Jahr. Min., 1845, p. 831. S'eues Jalir. Min., 1845 p. 831. Min. Mitth., 1882 (2), 2.66 2.705 36154 2.63 40.43 40.47 40.50 40.52 40.32 40.55 trace. 4.35 3.25 0.21 2.70 .... 9.55 7. 18.50 10.40 4.23 31 3.01 3.33 3.51 0.84 6.25 4.40 Meteorite. Meteorite. Picrite. Serpentine. Tyrol, lochester, Indi- ana. )hurmsalla, India. Freiberg, Neutit- schein, Moravia. Talof Copper Mine, Ural. J. L. Smith. S. Hanghton. P. Jubasz. Ivanoff. H Hofer. v. 67. Am. Jour. Sei., 1877 (3) xiv. 219-222. Proc. Roy. Soc., 1866 xv. 214-217. Sitz. Wien. Akad., 1866, liii. (1), 265. Neues Jahr. Min., 1847 p. 207. Jabrb. Geol. Reichs. 3.55 3.399 2.96 2.65 40.61 40.69 40.79 40.80 40.81 0.10 0.60. 10.41 3.02 1.09 0.45 6.88 3.62 1.98 16.56 11.20 6.39 2.20 6.02 2.41 8.48 0.42 1.32 Austria. 1866, xvi. 443-446. Ann Mines 1850 (4) 2.749 40.83 0.92 7.39 1.50 Serpentine. Vosgcs, France. Corio, Piedmont. A. Cossa. xviii. :!41. Ric. Cliim. Roc. Italia 1881, pp. 123, 124. 2.64 (2.587 ) 40.88 4090 trace. .... 2.05 10.21 4.70 trace. 0.02 1881 pp 115-118 J 2.500 > 4086 4.59 O.OS E Hussak. Min. Mitth., 1882 (2) ( 2.546 ) 40.90 2.08 7.68 0.30 Tyrol. v. 70. 41.00 0.75 45.00 2.00 Meteorite. Serpentine. bynia, Russia. Searsmont,Maine Heiligenblut, Ca rinthia. J. L. Smith. R. von Drasche. f Keller 1824, xxv. 219-221. Am. Jour. Sci., 1871 (3) ii. 200, 201. Min. Mitth., 1871, p. 9. 3.701 2.91 41.04 41.05 41.12 0.86 1.67 3.22 13.16 1037 8.82 13.84 3.15 17.42 3.76 2.06 Meteorite. Kralienberg, Ba varia. 1878, viii. 47-58. 39.08 2.08 4.43 28.53 13.35 Dunite. Serpentine. Meteorite. Bonbomme, Vos ges, France. Neurode, Silesia. Stewart Co., Georgia. B. Weigand. Fickler. J. L. Smith. 1878, viii. 47-58. Min. Mitth., 1875, p. 187 Sitz. Wien. Akad., 1867 Ivi. 274, 275. Am. Jour. Sci., 1870 (2) 1. 339-341. Phil Mag 1855 (4) x 2.88 3.65 41.13 41.13 41.15 41.24 0.84 13.56 2.17 6.09 3.86 2.77 6.19 14.85 7.41 trace. 0.72 0.04 Villa Rota Italy 364. Ann Mines 1848 (4) 2.644 41.34 3.22 6.54 xiv. 79. The prefixed asterisk indicates that the specimen is a meteorite. ANALYSES OF METEORIC AND TERRESTRIAL ROCKS. XXVll KgO. MnO. NajO. K.,0. CrJ) a . Ni. Co. Cu. Sn. P. S. HoO Miscellaneous. Total. 20.11.". ou:;r, 0.519 trace. Cr,0 3 +FeO (Mill 1.191 ' 0.042 2.516 Mn 0.228. llS.ltt! "11 (!'." ll.nl/, 0.734 0.988 1 20; t 0.061 2.221 Mn 0.185. !)7 7^2 2.50 S+Cr..O 3 1.00, Mn 1 .00. 90.50 27 :::', 1.03 0.45 0.13 2.00 1.01 1 0.02 1.81 Mn 1.00. Recalculated b\ 98.70 "I ) .',."> 1.53 131 1'A 022 1 66 A. Kulilberg. 0902 31.21 0.90 13.00 99.66 ;;'.HI7 Nil) 1336 100.00 8746 C 0.72, II 0.13. Recalcu 101.08 "1 (i:; 361 082 504 lated by Tescliernmk. 9977 9.86 100.13 87.43 OjOg+FeO "747 NiO 0.16 Ignition 13 90. 100.00 31.82 trace. HIO 0.06 10.05 100.25 34.69 0.15 NiO 0.49 H 2 O+FeS 1161. 100.11 9.00 1.25 2.00 10.00 8.12 Loss 1.13. 100.00 42.05 13.85 C 0.30. 99.94 41.70 1354 98.95 BUM 9.32 100.96 28.73 0.67 0.05 0.42 005 FeS 3.00. Recalculated. 101.85 26.59 1.21; 0.39 0.21 Cr 2 O 8 +FeO "4.16 1.54 FeS 6 61. Recalculated. 90.14 2::.:: I 1.71 0.71 404 CO 2 trace 9939 40.50 0.20 1202 99.24 37.1 1'j 0.01 0.32 10.26 98.53 37.98 trace. 0.68 Ignition 10 70. 100.00 34.H4 trace. Nil) 051 11 74 98.02 41.31 trace. 0.02 NiO 0.08 1'A 1340 100.43 41.87 trace. 0.03 0.09 1308 100.05 37.40 12 16 100.56 14.90 Mn trace. 0.75 1.00 400 109.40 26.10 88.70 V . 0. , ' 50 Undt. ISO 0.06 Undt. .... Undt. .... L,i 2 O = trace. Recalculated. 98.61 100.60 18.02 0.78 0.17 1.22 0.89 UK BnOJ 18" 046 235 100.82 5.97 0.82 1.81 1.48 0.39 1 31 99.26 41.88 trace. trace. trace. trace. Nil) 100.60 22.52 0.98 0.83 Cr.,0 3 +FeO "2.1'J 8.30 1112.40 28.13 1.00 trace. 0.85 0.05 FeS 6.10 L1..O trace. Re- 100.59 30.28 14 16 calculated. 09.09 37.01 trace. trace. 1206 99.67 XXVlll A CLASSIFIED LIST OF COMPLETE (BAUSCH) TABLE IV. Variety. Locality. Analyst. Publication. Sp. Gr. Si0 2 . AL 2 O a . Fe. Fe,0 3 . FeO. CaO. Picrite. Serpentine. Serpentine. Dunite. Schriesheim, Ba- den. Hillswick Ness, Scotland. Windiseli-Matrey, Tyrol. Franklin, Macon C. W. C. Fuchs. M. F. Heddle. It. v. Drasehe. T. M. Chatard. Neues Jahr. Min., 1804, pp. 820-332. Min. Mag., 1880, iii. 21. Min. Mitth., 1871, p. 4. Geol. North Carolina, 2.82 2.522 2.69 41.44 41.46 41.57 41.58 6.63 0.01 0.67 0.14 :: 13.87 2.422 2.63 6.30 i.iea 5.31 7.49 7.20 trace. 1.22 0.11 Meteorite. Co., N. C. Mezo-Madaras, Transylvania. f Woliler and Atkin- < son. ( C. Rammelsberg. 1881, p. 42. Phil. Mag., 1856 (4),xi. 141-143. 3.50 41.62 37.64 3.15 3.41 18.10 12.12 .... 4.61 1544 1.80 1 08 Serpentine. Kuhstein Bava- G. Schulze. 1871, xxiii. 734-737. Zeit l)eut geol Gesell 41.63 1.46 385 467 3 57 Lherzolite. Serpentine. ria. Germagnano, Piedmont. Dillenburg, Prus- A. Cossa. C. Schnabel. 1883, xxxv. 447. Ric. ('him. Roc. Italia, 1881, pp. 112, 113. 3.116 41.06 41.70 4.25 7.04 .... 2.95 10.38 26.95 1.76 3 '-'A Serpentine. Meteorite. sia. Malenker Thai, Graubiindten. L. R. v. Fellenberg. worterbuch, 4, Supp., 1847, p. 200. Neues Jahr. Min., 1867, p. 197. Ann CbimiePhys 187 2.99 3.2442 41.72 41 75 3.19 .... 4300 7.06 Meteorite. Dunite. Lherzolite. llaly. Krahenberg, Ba- varia. Webster, Jackson Co., N. C. Mohsdorf, Sax- G. vom Rath. F. A. Genth. Leuckart. xxxiv. 139-142. Ann. Physik Cbemie, 1869,cxxxvii.328-336. Am.Jour. Sci., 1862(2), xxxiii. 199-203. Neues Jahr Min 1876 3.4975 (3.28 I 3.252 41.78 41.89 40.74 41.99 0.06 trace, trace. 6.734 6.31 9.143 19.53 7.39 7.2C 1.659 1.94 0.08 0.02 1.841 Serpentine. Meteorite. Lherzolite. ony. Radau, Ilarz. Guernsey Co., Ohio. New Concord, Ohio. A. Streng. J. L. Smith, f J. L. Smith. D. M. Johnson. pp. 232, 233. Neues Jahr. Min., 1862, p. 540. Am. Jour. Sci., 1861 (2), xxxi. 87-98. Am.Jour. Sci, 1861 (2), xxxi. 87-98. Am. Jour. Sc-i., 1860 (2), xxx. 109-111. 2.88 ' 3.55 3.55 3.5417 42.02 42.24 42.25 51.25 40.391 13.89 0.28 0.28 5.325 2.30 9.31 9.309 8.803 5.778 5.819 3.19 25.03 25.03 25.204 18.133 8.01 0.02 0.018 0.785 2.523 Serpentine. Goujot, Vosges, A. Delesse. 1863, p. 105. Ann. Mines, 1850 (4) 42.26 1.51 7.11 0.80 Serpentine. France. Poldnewnja, Rus- A A. Loseh. xviii. 342. Zeit. Kryst., 1881, v. 42.34 1.68 0.29 1.98 Lhcrzolite. sia. F Kohler. 591. Neues Jahr Min 1862 2668 42.36 2.18 0.03 Meteorite. Middlesborougb, AV. Flight. p. 541. Phil. Trans. 1882, pp 42.39 1.73 7.30 23.76 Yorkshire, Kng. 896-899. f 4253 2.22 V Merz 4227 1.88 sell* Xuricli 1861 vi 4244 1.80 369-372 i 4245 2.12 42 13 2.23 Lherzolite. Lherzolite. Sehillerfels. Germa. Miscellaneous. Total. IS IL' 0.24 0.93 5.00 10063 41 TO:! 0.2:3 1243 99478 NiO CO 2 051 Ignition 1 1 88 10045 4 '.I -.'I NiO 0.34 10060 s', si II -'S U) 050 1 45 0.05 Graphite 0.26 S+P+Cr/}. 10000 24.il 0.18 1.70 trace. 0.64 1.04 2.27 = 2.02. NiO 00 Recalculated. 10085 M.97 trace. 1.20 902 COj 86 10023 :;i r-2 0.32 4.95 101.09 lo-'t; 1158 10087 4 1-3 0.18 NiO 025 655 10155 1000 1.50 NiO 1.23 1.00 10450 21.11 trace. 1.00 CrjOrr-FcO " 0.5)1 0.64 2.17 Recalculated. 98.08 4!>.l:'. mo 0.35 CrjOs-l-FeO-t-SKJj 58 Ig- 100.21 4'.) 18 039 nition = 82. CtyOb+FeO-l-8iO< 1 83 Ig- 10018 31.40 trace. 7.094 nition = 0.70. 99951 20.97 0.36 0.44 Cr.,0,+FcO " 4.08 6.64 100.20 21.81 .Mn tnusc -. . 0. , ' J3 1.32 0.01 trace. trace. 006 10101 11.91 .Mn trace. 0. )86 1.322 0.045 trace. 0.001 0.113 101.264 8.873 230 1 184 0035 103.819 U41 Mn tract-. 0.235 NiO 0.812. 99.501 38.90 trace. trace. Ignition 9 42 10000 40.83 trace. 100.13 28.90 0.85 Cr..(),+FeO "13.27 1207 10026 uiaa Undt. Undt. 2.00 0.08 98.08 42.:M 1364 100.78 4:! 10 13 69 1(1084 42.97 1348 100.69 42..'iii 13.70 100.83 !". o 1300 10086 87.50 0.25 3.54 98.54 16.96 30.11 1.12 1.20 0.50 0.21 0.10 Cr^Oa+FeO 1.50 trace. 1.38 trace. .... .... 0.41 2.61 328 Mn = 0.57, Li 2 O= trace, C? = 0.19. 09.51 98.87 47.:J8 trace. NiO trare. 067 CoO trace. 100.16 40.90 Ni trace. 049 100.17 9.01 40..32 .... 1.65 1.01 .... .... .... i'A trace. .... 2.70 1204 Cl = trace, CO. 2 = 6.88. Rock altered. 99.09 99.84 40.04 0.18 11 89 99.96 IMS trace. 0.90 0.15 !'.", 344 TiO 2 trace CO 2 2 65. 99.95 10.22 (race. 0.93 0.10 3 4.'! TiO^ trace COj 2.05. IMP XXX A CLASSIFIED LIST OF COMPLETE (BAUSCH) TABLE IV. Variety. Locality. Analyst. Publication. Sp. Gr. Si0. 2 . A1 2 3 . Fe. Fe 2 3 . FeO. CaO. Lherzolite. Dreiser Weiher, C. Rammelsberg. Ann. Physik Chemie, 4298 1.74 859 J .;() Meteorite. Serpentine. Serpentine. Serpentine. Eifel. Lissa, Bohemia. Westfield, Mass. Germagnano, Piedmont. Gornoschit, Rus- M. H. Klaproth. E. Hitchcock. A. Cossa. F. v. Schaffgotsch. 1870, cxli. Sl'2-519. Bei trage M ineralkorper, 1810, v. 246-253. Geol. Mass., 1841, p. 160. Ric. Chim. Rnc. Italia, 1881, pp. 121, 122. Rose, Reise nach dem 3.56 2.615 43.00 43.03 43.44 43 734 1.25 0.42 0813 29.00 8.08 0.91 2.84 6 111 0.00 Serpentine. ila. East Goshen, S. P. Sharpies. Ural, 1857, i. 245. Am. Jour. Sei., 1806 (2) 4389 1 38 Meteorite. Serpentine. Lherzolite. Meteorite. Meteorite. Chester Co., Penn. Sienna, Italy. Haaf-Grunay Is- land, Scotland. Knyaliinya, Hun- gary. Danville, Alaba- ma. Uden, North Bra- M. H. Klaproth. M. F. Heddle. E. H. von liaiiin- hauer. J. L. Smith. Baumhauer and xlii. 272. Mem . A cad . Berlin, 1803, pp. 38-42. Min. Mag., 1870, ii. IOC. Archives Nc'erland., 1872, vii. 146-153. Am. Jour. Sci., 1870 (2), xlix. !K)-93. Ann. Physik Chemie, 3.34-3.40 3.515 3.398 3.4025 44.00 44.003 44.30 44.47 44.579 3.057 1.68 4.10 2.25 2.58 0.108 25.00 6.286 16.379 23.44 22.409 2.727 0.22 2276 Serpentine. bant. Saxony. Seelheim. A. Vogel. 1862, cxvi. 184-188. Gelehrte Anzeig. Mun- .J 44.70 1.24 13.20 Meteorite. Meteorite. Meteorite. Harrison Co., In- diana. L' Aigle, Orne, Prance. Sauguis-Saint- J. L. Smith. {E. H. von Baum- hauer. Foucroy and Vau- quelin. S. Meunier. chen, 1844, xix. 115, 116. Am. Jour. Sci., 1859 (2), xxviii. 409-411. Archives Nc'erland., 1872, vii. 154-160. Ann. Mus. Hist. Nat., 1804, iii. 101-108. Comptes Rendus, 1808, 1 3.405 3.607 3.49-3.626 3.309 43.10 44.80 44.81 53.00 44.879 1.94 2.23 2.34 4.26 36.00 15.60 24.80 18.34 4.022 0.77 4.03 1.00 050 Lherzolite. Meteorite. Etienne, Mau- le'on, France. Vicdessos.France. Forsyth Georgia. H. A. v. Vogel. C. U. Shepard. Ixvii. 873-877. Jour. Mines,1813,xxxiv. 71-74. Am. Jour. Sci., 1848 (2), 3.25-3.333 45.00 45.00 1.00 1.62 8.90 12.00 29.90 19.50 4 77 Meteorite. Lherzolite. Bremerviirde, Hannover. Baldissero, Pied- F. Wohler. A. Cossa. vi. 406, 407. Ann. Chemie Pharm., 1856, xcix. 244-248. Ric. Chim. Roc. Italia, 3.64 2.269 45.40 45.68 2.34 6.28 21.61 .... 4.36 9.12 Undt. 2.15 Picrite (Pa- laeopicrite). Meteorite. mont. Ottenschlag, Aus- tria. Moresfort, Tippe- A. Gamroth. W. Higgins. 1881, p. 105. Min.Mitth. ) 1877,p.278. Phil.Mag.,1811,xxxviii. ( 3.67 45.03 46.00 15.09 42.00 1.87 11.45 8.92 262-268. ( 3 6478 48.25 39.00 Lherzolite. land. Corio, Piedmont. A. Cossa. Ric. Chim. Roc. Italia, 3.225 46.46 2.85 15.22 3.35 J. S. Brazier, 1881, pp. 100, 110. Neues Jahr Min. 1879, 47.15 0.90 3.40 9.56 1.61 Peridotite. St. Paul's Rocks, Atlantic Ocean. L. Sipiicz. J. S. Brazier. pp. 390-394. Rep. Challenger Exp., Narrative, 1882, ii., App. B. Rep. Challenger Exp., 3.287 43.84 43.50 1.14 0.38 .... 1.92 8.76 8.01 1.71 C. U. Shepard. Narrative, 1882, ii., App. B. 300-3.66 56.168 1.797 18.108 trace. North Carolina. Sci., 1850, iii. 149-152. * The prefixed asterisk indicates that the specimen is a meteorite. ANALYSES OF METEORIC AND TERKESTRIAL EOCKS. XXXI Continued. KgO. MnO. No,O. K/>. Cr 2 s - Ni. Co. Cu. Sn. P. S. HjO. Miscellaneous. Total. 4" .",' Cr,0,, + FeO 100 99.19 2200 Mb 05 050 S+loss 3 50. 10000 13.93 Loss 0.42. 100.00 41 15 1206 100.82 37710 11.626 100.00 4048 13.45 99.20 2200 025 000 Loss 5 40. 10000 80714 trace. 13.20 100.311 2 10 100 0658 O 2 O,-i-FeO 080 FeS 2.22 Fe+Ni 5 00. 98.282 20.09 20GG7 trace. 043 0.49 094 0.62 0.49 trace. Cr.,O 3 +FeO "0 70 0.28 NiO 029 0.01 trace. .... trace. 0.98 .... Recalculated. Li.jO = trace. Recalculated. Ni+Fe+S 1.707 FeS 0.718. 99.84 99.424 '-: :.n 0145 11 20 C o 192 99277 l!ii "D 17 1240 C 20. 'J'J 01 trace. 0.40 065 065 0.02 trace. trace. trace. Recalculated. 104.80 1993 123 085 OoO.+FeO 000 Fe+Ni 8.00, FeS 1.80 101.93 900 300 2.00 Recalculated. 104.00 39409 trace 0454 0012 Al0,+FeoO-, 0604, Fe-f-Ni 100.574 1600 050 = 8.05, FeS = 3.044. Loss 00 10000 8.37 096 Cr. 2 O,-(-lo8s 0.14. Recalcu- 99.60 2240 Undt 118 037 Cr.,O,+FeO "031 1 89 Undt Undt Undt lated. Graphite 0.14. 10000 34.76 0.26 121 9946 1482 1.93 022 058 lOO'.Sl 12.25 1 50 400 105.75 900 1 70 400 10200 3008 trace. 072 99.28 36.69 Loss 0.50, CaS 0.29. 100.00 41.:;:; 0.12 0.42 NiO 100 x 106 101.89 KM CaSO 4 0.96, Ca s P 2 O 8 = 0.28, 100.00 10.400 trace. trace. OCO. 0.47, Ignition = 4.20. Fe+Ni 6.32, FeS = 3.807, 100.00 Loss = 3.394. XXX11 A CLASSIFIED LIST OF COMPLETE (BAUSCH) TABLE V. Basalt. Variety. Locality. Analyst. Publication. Sp. Gr. Si0. 2 . AL,0 8 . Fe. Fe 2 3 - Basalt. Basalt. Basalt. Basalt. Gabbro. ., I'' Gabbro. onzac, France. Stannern, Iglau, Moravia. Constantinople, Turkey, 'etersbnrg, Lin- coln Co., Tenn. Tuvenas.Ardeclie, France. Shergotty, India. Charkow, Russia. Frankfort, Frank- lin Co., Alabama. Kulesi'linwka.Pol- A. Laugier. C. Rammelsberg. M. H. Klaproth. J. Moser. L. N. Vauquelin. E. Ludwig. J. L. Smith. {C. Rammelsberg. A. Laugier. L. N. Vauquelin. f E. Lumpe. 1 F. Crook, f J. Scheercr. 1 Suhnaubert and Giese. G. J. Brush. J. Scheercr. C. Riimmelsberg. - N. S. Maskelyne. H. Fiildington. f N. S. Maskelyne. [ W. Dancer. f A. Sclnvager. ilmhof. N. S. Maskelyne. R. Prendel. G. vom Rath. C Rammelsberg. J. L. Smith. W. S. v. AValters liausen. { C. V. Shcpard. M<5m. Mus. Hist. Nat., 1820, vi. 233-240. Ann. Physik Chemie, 1851, Ixxxiii. 591-593. Beitrage Mineralkorper, 1810, T. 257-263. Ann. Physik, 1808, xxix. 309-327. Ann. Chimie, 1809, Ixx. 821-330. Min. Mitth., 1872, pp. 85-87. Am. Jour. Sci., 1861(2), xxxi. 264-266. Ann. Physik Chemie, 1848, Ixxvii. 585-590. ' Ann. Chimie Phyi^WBl, xix. 26^-273. Ann. Chimie Phys., 1821, xviii. 42H23. Min. Mitth., 1871, pp. 55, 50. Chem. Const. Met. Stones, pp. 30-33. Me'm. Acad. St. Pe'tersbourg, 1813-14, vi Hist., p. 47. Ann. Physik, 1809, xxxi. 316-322. Am. Jour. Sci , 1869 (2), xlviii. 240-244. Me'm. Acad. St. Pe'tersbourg, 1812, v., Hist, pp. 22, 23. Mon. Berlin. Akad., 1870, pp. 316-322. Phil. Trans., 1871, clxi. 366, 367. Jour. Asiat. Soc. Bengal, 1851, xx. 209-314. Phil. Trans., 1870, cxl. 193-211. Phil. Trans., 1870, cxl. 193-211. Sitz. Miinchen Akad., 1878, viii. 32-40. Sitz. Munchcn Akad., 1878, viii. 34. Phil. Trans , 1870, clx. 211-213. Me'm. Sci. Nat. Cherbourg, 1877-78, xxi 203-207. Sitz. nicder. Gesell. Bonn, 1871, xxviii. 142- 145. Mon. Berlin. Akad., 1861, pp. 895-900. Am. Jour. Sci., 1864 (2), xxxviii. 225, 220. Ann. Chemie Pharm., 1851,lxxix. 369-374. Am. Jour. Sci., 1846 (2), ii. 380, 381. 3.12, 3.0773, 3.0897 2,90-3.20 2.95-3.16 3.077-3.1529 3.19 3.17 3.20 3.099-3.148 40.00 48.30 48.25 46.25 50.00 48.59 49.21 49.23 . 40.00 40.00 50.21 36.211 51.00 48.00 51.33 52.00 52.64 4537 6.00 12.65 14.50 7.62 9.00 12.63 11.05 12.55 10.40 13.40 5.90 1.871 36.00 23.00 27.00 29.00 0.50 0.16 1.21 23.50 8.143 19.80 3.00 3.4902 3.31 3.539 3.412 21 78 Basalt. 8.05 1.60 trace. 10.00 18.40 Gabbro. Gabbro. Gabbro. Gabbro. tawa, Russia. Shalka, India. Busti, India. Massing, Bavaria. 3.66 C8.60 52.871 0.60 26.80 5273 3.3636 3.365 3.198 53.115 31.00 53.629 53.81 54.49 57.52 I 00.12 ) 5'.).83 07.140 70.41 8.204 0.52! 1.80 32.54 dt'ish, India. 8.75 1.06 2.72 9.41 Gabbro. Gabbro. son, Russia. IbhenbiireM, Westplmlia. Bishopville.Soutl Carolina. 3.40-3.43 O.SO 0.50 1.706 3.039 3.116 1.478 ANALYSES OF METEORIC A^D TEEEESTEIAL EOCKS. XXXlll Part I. The Meteoric Basalts. FeO. CaO. MgO. Mn<>. Na,O. K,0. Cr,0 3 . NL P,0 6 - S. H 2 0. Miscellaneous. Total. 7.50 1.00 2.60 1.00 1.60 10240 10.83 11.27 6.87 0.81 O.M 0.23 Cr 2 O 3 +FeO 0.64 FcS trace. . 10061 9.50 2.00 Loss 2.75 10000 !-' 12 2.50 0.75 Cr,0 8 trace. Loss 3.76. 10000 12.00 1.00 " 10100 2099 lo:;:i 6.10 trace. 0.46 0.16 Cr 2 O 3 +FeO 0.44 FeS trace 9982 20.41 '(>:::; 9.01 10.2! 8.13 0.44 0.82 0.63 0.12 0.24 trace. P trace. 0.28 0.06 0.09 TiO 2 10. 99.23 101 61 9.20 0.80 6.50 0.20 1.00 0.50 Cu 010 .. . 9220 *- 8 * ' 00 Na,O+K,O-f-Cu+Cr,0 3 +S 11 60 10000 21.85 10.41 10.00 1.28 O.C7 Fe+Mn = 27.00. 10022 '21 I "i 0.4:!o 24.114 0223 0.109 0.237 1.30 P trace. trace 99778 20.50 1 60 Mn 2 O 3 4 20 Loss 3 00 10000 22.05 1.00 Mn 2 O, 6.00 9943 1370 7.03 17.59 0.45 0.22 0.42 023 9902 960 1 20 425 CaO + Mn -floss 2 95 10000 18.78 0.55 26.38 0.40 023 Mean analysis of the crust and interior. 9998 19.06 2.214 15.636 Cr ,O 3 +FeO 17.717. . . 99997 2.00 010 012 98 12 0194 I"::'.i7 28.321 0.573 0.39 Li,O 0019 CaS 4133 CaS0 4 100 18 4.28 lli i::s 1.18 6.780 37.22 8.485 0.01 1.928 trace. 1.188 0.979 XiO 0.78 trace. 0.374 0.02 0.442. CaCl = 0.01 , Na. 2 S = 0.76, Li/) = trace, CagPOg = trace, CaS0 4 = 1.58. 99.47 9972 23.25 135 Loss etc 10 06 10000 20.476 1.495 23.32 Cr.,0 3 -t-FcO " 1.02'J 00 949 2.07 18.54 trace. ^7 V ' 14 trace. 0.70 FeS 5.26 99 08 IT. 'U 1.22 20.12 0.28 10077 1.25 0.66 34.80 KM 0.20 1.14 0.74 0.70 tnice. Ignition = 80 99.79 10061 :v.< i"J 074 trace. 10029 1.818 .'7.115 trace. 0671 99 ys 28.25 1 30 10005 PLATE I. FIG. 1. Pallasite. ATACAMA, BOLIVIA. PACKS A tracing made from the polished surface of a specimen. The coloring is conventional in this and in the next three figures. The yellow portions are the olivine grains, while the gray reticulated portion indicates the metallic iron and pyrrhotite, since no distinction of the different constituents was possible in a tracing except to divide them into silicates and metallic portions 70 FIG. 2. Pallasite. KRASNOYARSK, SIBERIA. Tracing, as in Fig. 1 71, 72 FIGS. 3, 4. Pallasite. RITTERSGRUN, SAXONY. Tracings of two opposite sides of the same polished slab. All these tracings are of natural size and form, so far as it was possible to make them 72, 73 FIG. 5. Pallasite, Cumberlandite. IUON MINE HILL, CUMBERLAND, RHODE ISLAND. A slightly magnified portion of a section. The dark portions represent magnetite, and the light parts the oliviue with a minute portion of feldspar. While in the four preceding figures the sponge-like structure of the metallic parts with the enclosed silicates could alone be shown, in this and in the following figures the minerals are in general differentiated, and the fidelity of the lithographer's work, in representing the form, structure, fissuring, coloring, etc. of the natural section, will be appreciated by all familiar with such rocks. This figure shows the same sponge-like structure as the preceding figures, but with the metallic iron replaced by its oxidized form 75, 76 FIG. 6. Pallasite, Cumberlandite. IRON MINE HILL, CUMBERLAND, RHODE ISLAND. This figure is from a section of the same rock-mass as the preceding, and shows the same general structure ; but the olivine of Fig. 5 is here replaced by serpentine, which retains the outlines of the former, and marks its fissures by secondary magnetite grains 78, 79 MEM MUSEUM COMPZOOL VOL. XI. PLATE 3. fc TOsytw, i *5gftlw *^*^t^\*V 9 4. (i. MEWadiworth.dd A-JInnel hlKBoiun PLATE II. Fio. 1. Pallasite, Cumberlandite. IRON MINE HILL, CUMBERLAND, RHODE ISLAND. PAGES This figure illustrates a more highly magnified intermediate stage in the same rock-mass, lying between that presented in Figs. 5 and 6 of Plate I. The dark portion represents the mag- netite sponge which holds the lighter silicates. The brownish portion represents the smoky, fissured, somewhat altered olivine, which is surrounded by a grayish and white actinolite, produced by the alteration of the olivine on its borders. The ragged character of the mag- netite borders, as shown in the figure, also indicates that it is associated in the change, or affected by the alteration 77, 78 FIG. 2. Pallasite, Cumberlandite. TABERG, SWEDEN. This shows the same general structure of magnetite enclosing silicates, principally olivine, as the three preceding figures. The reddish-brown spots at the bottom of the figure represent a secondary mica (biotite) produced in connection with the magnetite 81 FIG. 3. Pallasite, Cumberlandite. TABERG, SWEDEN. This figure represents a more highly altered portion of the same section as that shown in Fig. 3. The magnetite is less in amount, having been partially removed, and the reddish-brown biotite more abundant, while the silicate portions are more altered. 81 FIQ. 4. Peridotite, Saxonite. IOWA COUNTY, IOWA. The grayish and brownish parts represent the granular groundmass of olivine and enstatite sprinkled with ferruginous particles and enclosing the steel-gray masses of metallic iron. The orange-brown represents the ferruginous staining. A little to the right of the centre of the figure is represented an olivine cliondrus composed of the colorless olivine grains held in a grayish base 86-88 FIG. 5. Peridotite, Saxonite. IOWA COUNTY, IOWA. This represents one of the larger chondri, composed of olivine and enstatite, which blends at the lower portion of the figure with the general groundmass. The enstatite and olivine grains are held in a gray base, which is here given too dark a shade. The metallic iron and the ferruginous staining are represented by the steel-gray and orange-brown colors 86-88 FIG. 6. Peridotite, Saxonite. KNYAHINYA, HUNGARY. This shows a granular groundmass of chondri and olivine and enstatite grains, partially stained by ferruginous material to an orange- and yellowish-brown. One chondrus is shown extend- ing from the centre towards the right of the figure, which consists of a fan-shaped mass of grayish fibrous base, held in and cut by enstatite bars. At the base is shown a portion of another chondrus composed of radiating bands of enstatite and base. Towards the bottom of the figure, and at the left of the centre, is shown an elongated fissured enstatite crystal. The metallic iron grains are indicated as before. . ... ... 88-91 MEM MUSEUM COMP ZOOL.VOL.XI. PLATE il t Wldiworth dl PLATE III. FIG. 1. Peridotite, Lherzolite. PULTUSK, POLAND. PAGES This shows a portion of a section with two chondii at tlie base of the figure, while the remaining upper portion is made up of an aggregate of cliondri, olivine, enstatitc, dial luge, pyrrhotite, and iron grains. The larger and darker chondrus is composed of aggregately polarizing fibrous enstatitic material. This chondrus shows rounded indentations, and on its left is another form, composed of alternating colorless enstatite ribs and bands of gray base with minute iron granules. The dark portions of the figure represent the iron and pyrrhotite, and the yellowish-brown the ferruginous staining 94, 95 FIG. 2. Peridotite, Lherzolite. PULTUSK, POLAND. This displays the structure of a chondrus composed of olivine, enstatite, iron, etc., cemented by a gray base. This chondrus occupies the chief portion of the figure, but towards the bottom its gradual passage into the groundmass is shown. The ferruginous materials are colored as in Fig. 1 94, 95 FIG. 3. Peridotite, Lherzolite. PULTUSK, POLAND The brownish-black central portion is pyrrhotite surrounding a steel-gray pear-shaped mass of metallic iron. Surrounding the pyrrhotite is the chondritic groundmass of the meteorite, partially stained yellowish-brown 94, 95 . FIG. 4. Peridotite, Saxonite. WACONDA, KANSAS. This shows a mixed granular groundmass of olivine, enstatite, iron, and pyrrhotite, which is more or less stained a yellowish- and reddish-brown from the oxidation of the iron 93, 94 FIG. 5. Peridotite, Lherzolite. ESTHERVILLE, EMMET Co., IOWA. This shows a grayish and a greenish-yellow groundmass of olivine, enstatite, and diallage, with dark-colored iron and pyrrhotite, surrounding a larger crystal of diallage 97101 FIG. 6. Peridotite, Lherzolite. ESTHERVILLE, EMMET Co., IOWA. This represents a semi-sponge-like mass of iron and pyrrhotite with enclosed grains of olivine, diallage, and enstatite. On the left is figured a crystal of enstatite with its inclusions and characteristic cleavage ; while on the right is a crystal of diallage showing its cleavages. The yellowish-brown ferruginous staining is to be seen in some portions of the figure. . . . 97-101 MEM MUSEUM COMPZOOL VOL. XI. PLATE . a E Widiworth it. PLATE IV. FIG. 1. Peridotite, Lherzolite. NEW CONCORD, GUERNSEY Co., OHIO. PAGES This shows a grayish, crystalline, granular mass of olivinc, enstatite, and diallage, containing dark grains of iron and pyrrhotite. The grouudmass is stained by the oxidation of the iron to a reddish- and yellowish-brown 95, 96 FIG. 2. Peridotite, Dunite. FRANKLIN, NORTH CAROLINA. This figure represents a granular mass of olivine traversed by fissures, giving it a grayish appear- ance. A little below the centre, and also on the left of the figure, are two dark chromite grains. This, with the ten preceding figures, presents the structure of the unaltered peridotites. 118 FIG. 3. Peridotite, Duiiite. WEBSTER, NORTH CAROLINA. This represents ar. early stage in the alteration of the peridotites, in which a greenish and yellowish fibrous serpentine has been formed along the fissures of the olivine, leaving color- less grains in the interstices of the serpentine network. A further stage in the alteration is the change of some of the interstitial grains to a pale yellow serpentine. The reddish-brown grains sprinkled with black granules show the picotite, while the minute Ijlack grains in and about the serpentine indicate the magnetite produced during the process of the conversion of the olivine into serpentine 119,120 FIG. 4. Peridotite, Saxonite. ANDESTAD SEE, AURE, NORWAY. This figures a further change in a peridotite, in which the chief portion is altered to a greenish serpentine containing clear grains of unaltered olivine. In the upper portion of the figure is a partially altered enstatite traversed by fissures and containing much secondary magnetite dust. This enstatite is also partially altered to serpentine. Dark magnetite dust is shown in connection with, the olivine grains, while dark grains of chromite are figured in the serpentine 126, 127 FIG. 5. Peridotite, Serpentine. HIGH BRIDGE, NEW JERSEY. This represents an extreme stage/in the process of the alteration of a peridotite, in which is shown a yellowish and grayish serpentine mass blotched with aggregations of dark iron-ore grains. Extending across the figure is an irregular pronged grayish band, formed by serpen- tinized olivine traversed by numerous fissures filled with dust-like granules of iron ore. Enclosed in this gray band are greenish spots of partially altered olivine grains 157 FIG. 6. Peridotite, Lherzolite. JAINA RIVER, SAN DOMINGO. This shows a grayish-white serpentine mass holding dark patches of iron ore The yellowish- brown mass to the right of the centre is a diallage crystal altered to serpentine, the four white spots indicating the unchanged portions. The other yellowish-brown and greenish spots are serpentinized pyroxenes and olivines, while the gray irregular band on the left is a partially allured mass of diallage and feldspar 140 MEM MUSEUM COMPZOOL VOL. XI. PLATE IV S. -. - * o > : / ^ ^ '-irv b. / ^.-: ,.'%&*-. s&?,~.-i l -.^ ' ilh.Bo.UM PLATE V. Fia. 1. Peridotite, Lherzolite. COLUSA Co., CALIFORNIA. PAGES This represents one of the earlier stages in the alteration of a periclotite, showing a fissured granular mass of olivine, enstatite, and diallage traversed by a network of pale grayish serpentine, which borders the fissures. The mass is traversed by brown bands of serpentine, containing iron-ore dust along the medial lines. Dark grains of picotite or chromite lie in the upper part of the figure 129-131 FIG. 2. Peridotite, Lherzolite. COLUSA Co., CALIFORNIA. This shows a further alteration in the same type of rock as Fig. 1. In this the outline of the olivine can be distinguished by the yellow serpentine bands, while a later formation of ser- pentine shows in the orange-brown interior portions which retain in part grains of colorless unaltered olivine. The brown serpentine bands with their medial line of iron-ore dust are more abundant and better marked than in Fig. 1 ; while much of this secondary black dust is disseminated through the section 131, 132 FIG. 3. Peridotite, Lherzolite. COLCSA Co., CALIFORNIA. The principal portion of the figure represents a crystal of enstatite from the same section as that given in Fig. 2. The cleavage lines with their bordering gray and brown alteration products run more or less vertically, the latter containing considerable fine black ore-dust. On the right and left of the upper portion of the figure are shown portions of serpentinized olivine, like that given in Fig. 2. The two portions are connected by a yellowish branching vein of serpentine. The dark brown and black grains are picotite or iron ores 131, 132 FIG. 4. Peridotite, Serpentine. LA VEGA, SAN DOMINGO. This indicates a further stage of alteration than that shown in Fig. 2. The brown bands with their medial ore-dust remain, and are connected by finer brown bands marking the fissures in the original olivine ; while the interstitial olivine has been replaced by yellow serpentine. Towards the bottom of the figure, on the right and left, are represented two grayish-white altered enstatites. The series is continued in Figs. 2, 4, and 5 of Plate VI., and in Fig. 2 of Plate VII 154 FIG. 5. Peridotite, Serpentine. HIGH BRIDGE, NEW JERSEY. A grayish-white mass of serpentine containing disseminated dark iron-ore grains and dust ; and traversed by a band of serpentinized enstatite or diallage crystals, which are surrounded and cut by a brown serpentine holding black ore-dust 156, 157 FIG. 6. Peridotite, Serpentine. HIGH BRIDGE, NEW JERSEY. This is from the same section as Fig. 6, and contains the same serpentine groundmass which, in places, is stained yellow. Scattered through the groundniass are iron ores and brown ser- pentine pseudomorphs after olivine containing ore-dust, and showing part of the original olivine fissures by the traversing bands of grayish-white serpentine 156,157 MEM MUSEUMCOMPZOOL VOL. XI. PLATE V II K.W~3yt ra&v : -worth H-i UKBoiun. PLATE VII. FlG. 1. Enstatite. CoLDSA Co., CALIFORNIA. PACKS This is figured from the same rock as Figs. 2 and 3, Plate V. It indicates the manner in which enstatite is altered to serpentine. The longitudinal cleavage runs from side to side, and is crossed hy the vertical fractures. The unchanged enstatite is colorless, but upon the borders of the cleavage planes and cross fractures the mineral has been altered to a greenish and yellowish serpentine. A yellowish serpentine vein runs from the upper left-hand portion of the figure to the centre of the base 131,132 FIG. 2. Peridotite, Serpentine. WESTFIELD, MASSCHUSETTS. This continues the series formed by Figs. 1, 2, and 4 of Plate V., and Figs 2, 4, and 5 of Plate VI. Here the serpentine is of a pale yellow without trace of the usual network, and much of the black iron ore has been arranged in the form of a rectangular grating 159,160 FIG. 3. Peridotite, Lherzolite. PBESQUB ISLE, MICHIGAN. This shows a grayish and greenish partially serpentinized enstatite containing black iron ore and holding rounded olivines. These are fissured and rendered opaque in portions owing to the precipitations of magnetite dust along the borders of the fissures. Greenish and yellowish serpentine is also to be observed in connection with both the enstatite and olivine 130 FIG. 4. Peridotite, Lherzolite, Serpentine. PRESQUE ISLE, MICHIGAN. This is drawn from a portion of the same continuous rock-mass as Fig. 3, and represents a more highly altered state of the rock. The enstatite and diallage are largely replaced by greenish serpentine, bluish-green and yellowish biotite (?), gray dolomite, and black iron ores. The olivines are in part still more opaque from the rejected iron ore, and they have so far been changed to serpentine that comparatively few clear, unaltered, interstitial fragments remain. The structure is confused, and the distinctness of the minerals confused by the alteration. . 136, 137 FIG. 5. Feridotite, Lherzolite, Dolomite. PRESQDE ISLE, MICHIGAN. This is from the same continuous mass of rock as Figs. 3 and 4, and displays a further stage in the alteration. The groundmass is formed by a grayish mass of secondary granular dolomite, which holds yellowish, bluish-green, and brown pseudomorphs of serpentine and ferruginous material after olivine 137 FIG. 6. Peridotite, Serpentine. FITZTOWN, BERKS Co., PENNSYLVANIA. This shows a yellow serpentine mass containing grayish and colorless grains of olivine. The brown masses represent secondary dolomite grains formed in the serpentine, but the lithog- rapher has given them much too dark a color, since the grains figured are of a cloudy-gray to brownish-gray color. 152 MEM MUSEUM COMPZOOL VOL. XI. PLATE VII 2. L.f^AJF^ <-VV ji&Ktm *-* W^.f/,tS.','- . J&. % -*.,, V. ' - ' M K Wirt I sel lilKBotin YE 03726