BERKELEY ITY Of GIFT OF MICHAEL REESE EARTH SCIENCES LIBRARY A HANDY-BOOK ROCK NAMES, 3KIEF DESCRIPTIONS OF THE BOCKS. BY G. HENRY KINAHAN, NGINEER DIPLOMATIST, TRIN. COLL. DUBLIN J MEMBER OF THE ROYAL IRISH ACADEMY J FELLOW OF THE ROYAL GEOLOGICAL SOCIETY, IRELAND J OF THE GEOLOGICAL SURVEY OF THE UNITED KINGDOM J ETC. ETC. usciS^a*^ LONDON: ROBERT HARDWICKE, 192, PICCADILLY. 1873. EARTH SCIENCES LIBRARY PKEFACE. A WANT expressed by many Geologists and often felt by the Author, is a classified HANDY-BOOK OF ROCK NAMES. It is hoped that, until a better appears, this Manual may be useful to the Public. To write such a work satisfactorily is no easy task. In other branches of Natural Science, such as Botany, Zoology, and the like, some systematic nomenclature has been followed, but in Geology no one system has been used, or all system has been ignored. It is not uncommon to find eminent Petrologists calling the same rock by several names, or, what is more per- plexing, using for a rock a name already given to a totally different one. At the present time Bock names are in such confusion that if an observer names a rock, without at the same time mentioning his authority, he may be supposed to be referring to a rock, or even rocks, totally different to that which he intended to illustrate. This irregularity has caused many names to be used, not only unscientifically but also absurdly, as the original name may refer to a mineral or character not possessed by the rock or rocks to which it is now applied. From the above it is evident that a compiler of such a book as this Manual must run contrary to the opinions and, A 2 IV PREFACE. prejudices of many geologists ; therefore some will find fault even if the work could be well done. I would wish to impress on my readers that this book has been written as a reference for surveyors and students while engaged in the field. Should they desire a perfect knowledge of rocks, they must study the various papers and works of the different eminent Petrologists. The work, necessarily, is far from perfect : still I hope it may be of some small use or help to learners of Geology. During the compilation of this Manual, the writings of numerous Petrologists have been con- sulted and quoted ; also works on general subjects from which information could be procured. Dana's suggestions as to the termination of Rock names have been adopted as far as practicable, while the older names for rocks are generally adopted, except when they are objectionable or better names have since been proposed. Such local names as were known are also given, as they may assist explorers in gleaning information about a country. To various fellow-labourers I am much indebted : to D. Forbes, F.R.S., &c., for infor- mation; also to W. King, Dep. Supt. Geol. Surv., India, and for his valuable assistance while arrang- ing and classifying the rocks. I should also men- tion the names of the Eev. M. H. Close, M.R.I.A., &c. ; Stackpoole Westropp, M.D., M.R.I.A., &c. ; and H. Leonard, M.R.I. A. ; besides others who have supplied me with lists of local names. G. H. K. CONTENTS. PREFACE ... Page iii INTRODUCTORY REMARKS ... 1 PART I. CLASSIFIED TABLE OF THE ROCKS 9 Order I. Ingenite Rocks ... ... ... ... ... 9 Class 1. Granitic Rocks ... ... ... ... 9 Class 2. Plutonic Rocks 10 Class 3. Volcanic Rocks ... ... ... ... 14 Class 4. Transition or Metamorphic Sedimentary Rocks 15 Order IT. Derivate Rocks 19 Class 1. Subaqueous Rocks ... ... ... ... 19 Class 2. Subaerial Rocks ... ... 24 PART II. Order I. INGENITE ROCKS 26 Class 1. Granitic Rocks 26 Group A. Intrusive Granite .'.. ... J ... 27 Group B. Granite for the most part non-intrusive 32 Group C. Protogene... 36 Group D. Elvanyte .'. 39 Class 2. Plutonic Rocks 43 Group E. Felstone 44 Group F. Whinstone ... ... ... ... 55 Group G. Rocks due to pseudomorphic action ... 63 Group H. Tuff 66 Class 3. Volcanic Rocks ... ... 69 Group I. Trachytic 70 Group J. Augitic ... ... ... 73 Group K, Tufa and Peperino ... 75 Class 4. Transition Rocks ... 76 Group L. Gneiss ... ... 77 Group M. Schist 80 VI CONTENTS. Group N. Slate ... Page 88 Group 0. Calcareous Bocks' .:', . ... ... 89 Group P. Pseudomorph Calcareous Eocks ... 90 PART III. Order II. DERIVATE' EOCKS '... 94 Class 1. Subaqueous Eocks '-..; ^ .... 94 Group A. Rocks for the most part' mechanically formed ... 94 Subgroup A . Arenaceous Eocks ... ... 95 Subgroup B. Argillous Eocks 99 Subgroup C. Fault-rock 106 Group B. Eocks for the most part chemically formed 106 Subgroup A. Haylyte ... ... 107 Subgroup B. Gypsum ... 107 Subgroup 0. Anhydryte 108 Subgroup D. Dolomyte ... ... ... ... 108 Subgroup E. Quartz a 108 Subgroup F. Limonite Eock ... 109 Subgroup 6r. Hematite Eock ... 110 Subgroup IT. Spherosiderite ... ... ...110 Subgroup 1. Minerals occurring as Eock Masses 111 Group C. Eocks partly mechanically, partly chemi- cally, and partly organically formed ... ... 1 1 2 Subgroup A . Laminated Coal ... , 112 Subgroup B. Limestone ... ... 115 Subgroup C. Dolomyte 120 Class 2. Subaerial Eocks ... 122 Group D. Mechanically, chemically, and organically formed ... 122 Subgroup A. Coal ... ... 122 Subgroup jB. Surface Deposit and Accumulations 126 HANDY-BOOK OF BOCK NAMES, INTRODUCTORY REMARKS. THE term ROCK, in a geological sense, includes every solid substance that is an ingredient, or forms part, of the earth. Thus loose sand, clay, peat, and even vegetable mould, geologically speaking, are rocks. Jukes thus defines a rock: " A mass of mineral matter consisting of many individual particles, either of one species of mineral, or of two or more species of minerals, or of fragments of such particles. These particles need not at all resemble each other in size, form, or composition ; while, neither in its minute particles, nor in the external shape of the mass, need a rock have any regular symmetry of form." Rocks are most variable in condition and structure ; soft or hard, loose or compact, friable or tenacious, coarse or fine, crystalline or homogeneous; or they may be scoriaceous, vesicular, hyaline, &c. &c. Rocks may be chemically, mechanically, or organically formed, or two or more of these com- bined; they may be stratified or unstratified, igneous or aqueous, or partaking of the nature of both. Various classifications have been adopted by different writers on the subject, each taking dif- 2 HANDY-BOOK OF ROCK NAMES. ferent peculiarities as a foundation for his system. Jukes and others have divided rocks into four classes ; namely, Igneous, Aqueous, Aerial, and Metamorphic; while Forbes, who wrote subse- quently, has simplified this division, and makes two great classes of all rocks. Forbes calls his first class by the names INGENITE or SUBNATE EOCKS; i.e., "such as are born, bred, or created within or below;" and the second he calls DERIVATE EOCKS, " since directly or indirectly they are all derived from the destruction of the former." Under Ingenite rocks are included all the true igneous, intrusive or irruptive rocks, whether they are still in their original state, or whether they have been subsequently affected by metamorphic action, as also the metamorphosed sedimentary rocks ; since all these have been bred or formed within or below the surface of the earth. Thus all granites, whether truly igneous or metamorphic,* are included. The Derivate order consists chiefly of sedimentary rocks, but it will include some, such as DoLOMYTE,f HALYTE, &c., which some authorities refuse to regard as sedimentary rocks. In this Manual these suggestions will be fol- lowed, and the rocks classed in two orders ; namely, * Some authorities deny that any granite can be of meta- morphic origin. To me, however, there does not appear to be any room for doubt, for in different places I have found granite graduating through gneiss and schist into unaltered rocks. t Dana suggests that all rock names ending in lie should be changed into yte, and the first termination should be kept solely for minerals. A general adoption of this suggestion would prevent the confusion that at present exists when so many rock masses and minerals have similar names, such as AUGITE, STEATITE, &c. &c. Dana's names for the minerals are those that will be used in this Manual. INTRODUCTORY REMARKS. 3 Order I., INGENITE ROCKS ; and Order II., DERIVATE ROCKS.* The first Order (!NGENITE ROCKS) can con- veniently be divided into four classes ; namely, I. GRANITIC, II. PLUTONIC, III. VOLCANIC, and IV. TRANSITION, or METAMORPHIC SEDIMENTARY ROCKS. f These classes, however, necessarily merge into one another. GRANITE may be a true in- trusive rock, or may have been formed in situ [i.e. where it is now foundj by .extreme meta- morphic action. Granite is supposed to have been formed under great pressure, at a considerable depth beneath the surface of the earth; conse- quently it is never accompanied by tuff. Of it Jukes says : " As the granite rocks are all hypo- genous, or nethef-formed that is, have all been consolidated before reaching the surface of the earth, they are necessarily devoid of ' ash/ [tuff,] or of any mechanically derived accompaniment whatever." Usually the sedimentary rocks associated with granite are more or less metamorphosed : some- times .the metamorphism is very slight indeed. This may be due to the granite having been formed at a lower zone or depth, and. intruded into its present place in a semi-liquid state, under such low pressure that its heat, latent or otherwise, was unable to affect the associated rocks ; or it may be * S terry Hunt and others have called the Derivate rocks by the Dame of INDIGENOUS KOCKS, and the Granitic and Igneous rocks, EXOTIC ROCKS. This classification, however, does not appear to include the metamorphic rocks, as they are in part indigenous, and in part exotic. t Some of the metamorphic rocks were originally sedi- mentary, while others evidently were igneous. In this Manual it has been considered expedient to describe the latter with the groups to which they originally belonged. 4 HANDY-BOOT OF EOCK NAMES. due to tKose rocks being composed of a (suppose siliceous) material not easily affected by metamor- phic action. Allied with the granites are granitic rocks, in which a considerable portion of the quartz crystal- lized out prior to the other constituents. This, according to Scheerer and others, debars them from being classed as true granites. Nevertheless, this definition is controverted by Forbes and others, who contend that in some true granites a portion of the quartz crystallized out previous to the other constituents. These granitic rocks or ELVANYTES (Quartz-porphyries) are allied to the granite, being mineralogically similar, and always destitute of tuffs : they never occur contemporaneous or inter- stratified with the sedimentary rocks, but rather in irruptive masses or dykes ; moreover, in places they merge into granite. On the other hand, it is not unusual at the margin of a mass of Elvanyte, or in dykes branching from a mass, to find Elvanyte changing into a rock identical with a Felstone. From these facts it would appear that Elvanyte is a connecting link between Granite and the Plu- tonic rocks. There is also another somewhat similar link ; namely, the metamorphosed Plutonic rocks, as they merge into Granite. The rocks here called PLUTONIC rocks can be divided into two groups ; namely, FELSTONES, or highly siliceous rocks, and WHINSTONES, or basic rocks. Some of the rocks placed in the first of these groups are however a connecting link be- tween the two, partaking of the nature of both, and merging on the one hand into Felstone, and on the other into Whinstone. These basic felstones are the HYBRID KOCKS of Durocher, and they in- clude all the rocks originally called EURYTES by INTRODUCTORY Daubuisson [from eureo, to fl<3^^ftffl|fC(;^s41y], on account of their fusibility. Felsioires proper con- tain over 68 per cent, of silica ; Durocher's Hybrid rocks between 65 and 55 per cent. ; while the Whinstones contain a large percentage of pyroxene or amphibole, or such minerals. Any of the Plutonic rocks may be contempo- raneous, i.e. interstratified with the sedimentary rocks. Under such circumstances they are often associated with beds of tuff. Tuff also on some occasions occurs in dykes and pipes, when, appa- rently, it is the remains of old vents or funnels of eruption. The VOLCANIC rocks appear capable of a division similar to the Plutonic rocks ; the highly siliceous or the TRACHYTES, and the basic, or the AUGYTES. In them are also hybrid rocks, for which Scrope has proposed the name of G-REYSTONE, and Abich that of TRACHYDOLERYTE. Volcanic rocks generally are accompanied by tuffs ; of which more hereafter. The METAMORPHIC SEDIMENTARY ROCKS may be placed here. They belong, indeed, also to the Derivate Order ; but, being compelled to make a selection, we place them under the Ingenite, as this arrangement seems to involve the least incon- venience. They are Ingenite Rocks, as they have been in a certain sense formed below, yet their materials were previously derived from the destruc- tion of other rocks, which gives them their rela- tion to the second Order. They are capable of a nearly inexhaustible subdivision, not only on ac- count of the different degrees of metamorphism to which they have been subjected, but also on account of the numerous and variable constituents entering into them. Allied to the metamorphic rocks are such deri- 6 HANDY-BOOK OF ROCK NAMES. vate rocks as Dolomyte, Ophyte, Steatyte, &c., in which a secondary or pseudomorphic action has taken place new minerals replacing the old con- stituents, and thereby changing the nature of the rock. The second Order (DERIVATE ROCKS) may be divided into two classes ; namely, I. SUBAQUEOUS, II. SUBAERIAL, which need not be dwelt upon now. This Manual is divided into three parts. Part I. is a classified table of the rocks; Part II. is a description of the Ingenite rocks; and Part III. is a description of the Deri vate rocks : while in the Index will be found an alphabetically arranged list of local, duplicate, and other rock names that do not appear in the classified table of the rocks. As before stated, Dana's termination of yte for rock names, on account of its convenience in distinction, is adopted; but at the same time the names ending in ite are also given for such as prefer them. The termination oid is only used to signify like, as Granitoid, granite-like ; ous means a constituent that gives a character to the rock, as Pyritous granite, granite containing pyrite; while the ter- mination ic points to quantity, as felsitic, contain- ing a quantity of felsite (orthoclase intimately combined with quartz. See quotation from Cotta, page 46). In Parts II. and III. a general description of each class is given, and a general description of each group ; while under each group will be found the subgroups, and under the latter the varieties, and, when necessary, the subvarieties. In these two parts names of classes are printed in large capitals, of groups in egyptian type, of subgroups and particular varieties in small capitals ; while the INTRODUCTORY REMARKS. 7 others, subvarieties and local names, are in italics. Synonymous names for groups, subgroups, and varieties are given when not highly objectionable, but the name that is considered most applicable appears first. Objectionable names, if mentioned, are printed in italics, and the objection to them, pointed out. All the groups are arranged under roman capitals; the subgroups under italic capitals ; the varieties under small italic, and the subvarieties under small roman letters. A student wishing to learn the description of a rock, must first look for the name in the Index, and if the name does not occur there, it will be found in the classified list in its proper group, class, and order ; he must then refer for the description to either Parts II. or III. NOTE. While this Manual was in the press, Professor Joseph Le Conte's excellent paper on the " Features of the Earth's Surface " was published in " The American Journal of Science and Art," third series, vol. iv. As in it the formation of metamorphic granite is explained (p. 468), the student may be referred to it. PART CLASSIFIED TABLE OE THE ROCKS, Order No. I.INGENITE ROCKS. (Divided into Classes, Groups, Subgroups, and Varieties.) Class I. GRANITIC ROCKS. Group A. INTRUSIVE GRANITE (Highly siliceous granite). Subgroup A. Pyritous intrusive granite. Var. a. Beresyte. B. Albitic granite. C. Schorlaceous granite. 1). Granityte. E. Felsitic granite. F. Greissen, or quartzitic granite. 6r. Porphyritic intrusive granite. H. Pegmatyte. Var. a. Graphic granite. b. Blumen granite. c. Plumose granite. Group B. GRANITE FOR THE MOST PART NON-INTRUSIVE (Basic or oligoclase granite). Subgroup A. Hornblendic granite. Var. a. Titanitic granite. b. Chloritic granite. c. Talcose granite. d. Epidotic granite. B. Graphitic granite. C. Hematitic granite. D. Pyritous oligoclase granite. E. Porphyritic oligoclase granite. F. Gneissoid granite. 10 HANDY-BOOK OF EOCK NAMES. Var. a. Nodular granite. b. Lenticular granite. Subgroup 6r. Intrusive oligoclase granite. H. Granitic felstone. Group C. PROTOGENE. Group D. ELVANYTE, or QUARTZ PORPHYRY. Subgroup A. Felsitic and felspathic elvanyte. Var. a. Orthoclasic elvanyte. b. Oligoclasic elvanyte. c. Eappakivi elvanyte. B. Quartzitic elvanyte. C. Micaceous elvanyte. D. Pyritous elvanyte. E. Hornblendic elvanyte. Var. a. Micaceous hornblendic elvanyte. b. Chloritic. * c. Felspathic. d. Pyritous. F. Chloritic elvanyte. G. Granular elvanyte. H. Compact elvanyte. /. Gneissoid elvanyte. J. Granitoid elvanyte. K. Pyromeride. Class II. PLUTONIC ROCKS. Group E. FELSTONE, or FELSYTE. Subgroup A. Petrosilex. Var. a. Felstone glass. b. Ribaned petrosilex. B. Quartzitic felstone. Var. a. Oligoclasic quartzitic felstone. b. Micaceous. c. Hornblendic. d. Chloritic. e. Pyritous. /. Striped. g. Variolitic. CLASSIFIED TABLE. 11 Subgroup C. Minette. Var. a. Fraidronyte. D. Euryte. Var. a. Orthoclasic euryte. b. Oligoclasic. c. Micaceous. d. Hornblendic. e. Chloritic. /. Quartzose. f. Euryte porphyry. . Amygdaloidal euryte. i. Vesicular, j. Compact. k. Slab. I. Cleaved. E. Compact felstone. F. Granular felstone. G. Friable felstone. H. Rubbly felstone. I. Cleaved felstone. J. Foliated felstone. K. Granulyte. L. Felstone porphyry. Var. a. Amygdaloidal felstone. b. Vesicular felstone. M. Gneissyte. Var. a. Quartzose gneissyte. b. Felsitic. c. Micaceous. d. Hornblendic. e. Syenyte gneissyte. /. Chloritic. g. Talcose. h. Porphyritic. i. Schistoid. N. Schistoid felstone. Group F. WHINSTONE. Subgroup A. Doleryte. Var. a. White rock. 6. Aphanyte-doleryte. B. Melaphyre. Var. a. Eukryte. 6. Magnetic melaphyre. B 12 HANDY- BOOK OF ROCK NAMES. Var. c. Micaceous. d. Porphyritie. e. Amygdaloidal. /. Vesicular. g. Variolitic. Subgroup C. Pyroxenyte. D. Diabase. Var. a. Pyroxenic diabase. b. Uralitic. e. Labradoritic. d. Oligoclasic. \e. Magnetic. /. Kersantyte. g. Calcareous diabase, h. Porphyritie. i. Amygdaloidal. j. Vesicular. k. Variolitic. I. Aphanyte-diabase. E. Gabbro. Var. a. Euphotide. b. Noryte. c. Hyperyte. F. -Dioryte. Var. a. Amphibolyte. b. Aphanyte-dioryte. c. Kersanton. d. Napoleonyte. G. Syenyte. Var. a. Quartzose syenyte. b. Titanitic. H. Hornblende rock. Var. a. Actinolite rock. b. Tremolite rock. c. Hyperyte. d. Dioryte. e. Syenyte. e. Felso-syenyte. /. Mico-hornblende rock. Group G. ROCKS DUE TO PSEUDOMORPHIC ACTION OR WEATHERING (Ingenite in part, derivate in part). Subgroup A. Ophyte. Var. a. Ophihornblende rock. B. Steatyte. CLASSIFIED TABLE. 13 Var. a. Felspathic steatyte. b. Pyroxenic. c. Amphibolic. Subgroup 0. Eklogyte. D. Epidosyte. E. Kaolin. F. Fuller's earth. 6r. Meerschaum. H. Magnesyte. Group H. TUFF (Ingenite in part, derivate in part). Subgroup A. Feist one tuff. Var. a. Quartzose. b. Calcareous. c. Pyritous. d. Cupriferous. e. Hematitic. B. Whinstone, or Basic tuff. Var. a. Hornblendic. b. Pyroxenic. c. Chloritic. / d. Calcareous. e. Pyritous. /. Cupriferous. g. Hematitic. C. Calcareous tuff. D. Arenaceous. E. Argillous. F. Hematitic. 6r. Pyritous. H. Cupriferous. I. Steatitic. J. Porphyritic. K. Nodular. Var. a. Concretionary tuff. b. Spheroidal. L. Shaly tuff. Var. a. Flaggy. b. Slaty. M. Conglomeritic tuff. Var. a. Brecciated tuff. b. Plutonic agglomerate. B2 ' >.?, 14 HANftYtpOOK OF EOCK NAMES. Class III. VOLCANIC ROCKS. Group I. TRACHYTIC GROUP. Subgroup A. Khyolyte. Var. a. Liparyte. b. Perlyte. c. Obsidian. d. Pumice. e. Phonolyte. B. Trachyte. Var. a. Sanidine trachyte. b. Drachenfels trachyte. c. Domyte. d. Andesyte. e. Trachydoleryte. / /. Granular trachyte. g. Compact trachyte. h. Trachyte porphyry. i. Trachyte lava. j. Alumstone. Group J. AUGITIC GROUP. Subgroup A. Augyte, or Doleryte. Var. a. Nephelite augyte. b. Haiiynophyre. c. Allogovyte. d. Common augyte. e. Anamesyte. /. Basalt. g. Porphyritic basalt. h. Amygdaloidal basalt. i. Basalt lava, j. Variolitic basalt. B. Leucityte. Var. a. Compact leucityte. b. Leucitophyre. c. Amygdaloidal leucityte. d. Leucityte lava. Group K. VOLCANIC TUFA AND PEPERINO (Ingenite in part, derivate in part). CLASSIFIED TABfetJNIVERSr 15 Subgroup A. Tufa. Var. a. Trachyte. b. Pumiceous. c. Phonolyte. d. Pozzuolana. B. Peperino. Var. a. Augyte. b. Leucityte. c. Palagonyte. C. Volcanic conglomerate. Var. a. Volcanic breccia. b. Volcanic agglomerate. Class IV. TRANSITION OR METAMORPHIC SEDIMENTARY ROCKS. Group L. GNEISS. Subgroup A. Felspathic and felsitic gneiss. Var. a. Orthoclase gneiss. b. Oligoclase gneiss. e. Alpinyte. d. Adularia gneiss. B. Micaceous gneiss. Var. a. Two-mica gneiss. b. White mica gneiss. c. Black mica gneiss. C. Quartzitic gneiss. D. Basic gneiss. Var. a. Hornblendic gneiss. b. Chloritic gneiss. c. Talcose gneiss. d. Protogene gneiss. E. lolitic gneiss. F. Hematitic gneiss. G. Graphitic gneiss. H. Common gneiss. Var. a. Compact gneiss. b. Slate gneiss. 16 HANDY-BOOK OF EOCK NAMES. Var. c. Bibaned gneiss. d. Fibrous gneiss. Subgroup I. Oblique gneiss. Var. a. Curled gneiss. b. Nodular gneiss. c. Conglomeritic gneiss. J". Porphyritic gneiss. K. Granitoid gneiss. X*roup M. SCHIST. Subgroup A. Argillyte. Var. a. Chiastolitic schist. 6. Phyilitic schist. c. Carbonaceous schist. d. Alum schist. e. Spilyte. /. Dolomitic schist. g. Folded argillyte. h. Contorted argillyte. i. Fibrous argillyte. B. Quartzyte. Var. a. Itacolumyte. b. Itabiryte. c. Felsitic quartzyte. d. Quartz rock. e. Fibrous quartzyte. /. Conglomeritic. C. Felsyte schist. Var. a. Micaceous. b. Quartzose. c. Pyritous. d. Bibaned. e. Mealy. /. Gneissoid. D. Mica schist. Var. a. Two-mica schist. b. Chloritic. c. Talcose. (7. Garnetiferous. e. Chiastolitic. /. Andalusitic. g. Amphibolic. CLASSIFIED TABLE. 17 Var. h. Epidotic. i. Quartzose. j. Felsitic. k. Calcareous. I. Schorlaceous. m. Pyritous. n. Pyrrhotitic. 0. Hematitic. p. Graphitic. q. Fine. r. Ribaned. s. Fibrous. t. Nummoid. u. Wavy. v. Frilled. w. Curled. x. Knotty. y. Nodular. z. Gneissoid. Subgroup E. Basic schist. Var. a. Hornblende schist. b. Actinolite. c. Chlorite. d. Chloritoid. e. Potstone. /. Talc schist g. Garnet. L Tourmaline. 1. Rhaetizitic. F. Metallic schists. Var. a. Mico-iron schist. #. Pyrite schist. c. Pyrrhotite schist. G. Burnt shale. Var. a. Burnt clay. 6. Rock slag. c. Porcelanyte. H. Minerals forming rock masses (see page 22). Var. a. Quartz. b. Corundum. c. Apatite. d. Magnesite. 18 HANDY-BOOK OF ROCK NAMES. Var. e. Orthoclase. /. Pistacite. g. Pycnite. h. Lepidolite. i. Lievrite. j. Magnetite. \ Anthracite. I. Graphite. m. Eisenkiesel. n. Garnet- rock. Group N. SLATE. [See Order II., Class L, Group A, Sub- group B, Variety d.] Group 0. CALCAREOUS ROCKS. Subgroup A. Schistose limestone. Var. a. Cipollino. b. Calciphyre. c. Hemitrene. d. Felsitic limestone. e. Statuary marble. /. Granular schistose limestone. Group P. PSEUDOMORPH CALCAREOUS EoCKS. Subgroup A. Schistose dolomyte. Var. a. Micaceous dolomyte. b. Pyritous. c. Saccharoid. d. Granular. B. Ophyte. Var. a. Ophidolomyte. b. Ophimagnesyte. c. Ophicalcyte. d. Ophyte schist. C. Steatyte. Var. a. Felsitic steatyte. b. Hornblendic. c. Pyroxenic. d. Micaceous. e. Steatyte schist. /. Pyrallolyte. g. Onkosin. D. Magnesyte. E. Smaragdite schist. CLASSIFIED TABLE. 19 Order No. II.DERIVATE ROCKS. (Divided into Classes, Groups, Subgroups, Varieties, and Subvarieties. ) Class I. SUBAQUEOUS BOOKS. Group A. KOCKS FOR THE MOST PART MECHANICALLY FORMED. Subgroup A. Arenaceous rocks. Var. a. Sand, gravel, and shingle. b. Conglomerate. Subvar. a. Calcareous. b. Hematitic. c. Cupriferous. d. Pyritous. e. Plumbeous. f. Shale conglomerate. g. Slate conglomerate. c. Breccia. Subvar. a. Calcareous. b. Hematitic. c. Cupriferous. d. Pyritous. e. Shale breccia. d. Sandstone and grit. Subvar. a. Calcareous. b. Argillous. c. Felspathic. d. Micaceous. e. Hematitic. f. Cupriferous. g. Pyritous. h. Tuffose. i. Pebbly, j. Cleaved, k. Oblique. 1. Concretionary. m. Spheroidal, n. Nodular, o. Lenticular, p. Friable. 20 HANDY-BOOK OF EOCK NAMES. Var. e. Flagstone. Subvar. a. Arenaceous. b. Argillous. c. Slabstone. Subgroup B. Argillous or Argillaceous rocks. Var. a. Clay, loam, mud, and silt. Subvar. a. Kaolin. b. Potter's clay. c. Brick clay. d. Fire clay. e. Clunch. f. Claystone. g. Clayrock. h. Lateryte. i. Fuller's earth. j. Bituminous clay. k. Saliferous clay. 1. Variegated clay. m. Hematitic clay. n. Ferruginous clay. 0. Book clay. b. Marl. Subvar. a. Calcareous. b. Dolomitic. c. Argillous. d. Arenaceous. e. Micaceous. f. Oil-slate. g. Glauconitic. h. Gypseous. 1. Shell marl, j. Mealy marl. k. Marl-stone. 1. Tutenic marl, m. Book marl. c. Shale. Subvar. a. Calcareous. b. Arenaceous. c. Micaceous. d. Bituminous. e. Carbonaceous. f. Hematitic. g. Cupriferous. CLASSIFIED TABLE. 21 Subvar. h. Flaggy. i. Congloineritic. j. Nodular. k. Concretionary. 1. Spheroidal, m. Lenticular. n. Mudstone. o. Tutenic shale. Var. d. Slate. Subvar. a. Koofing slate. b. Slab slate. c. Pencil slate. d. Novaculyte. e. Calcareous slate. f. Carbonaceous. g. Arenaceous. h. Tuffose. i. Ribaned. j. Conglomeritic. Subgroup C. Fault rock. Group B. ROCKS FOR THE MOST PART CHEMICALLY FORMED. Subgroup A. Halyte. Var. a. Granular. 6. Sparry. c. Fibrous. B. Gypsum. Var. a. Alabaster. 6. Granular gypsum. c. Compact. d. Fibrous. e. Selenyte. /. Tripe-stone. C. Anhydryte. Var. a. Granular. b. Compact. c. Fibrous. D. Dolomyte. E. Quartz. Var. a. Chert. 6. Flint. c. Menilyte. d. Jasper. 22 HANDY-BOOK OF EOCK NAMES. Var. e. Agate. /. Basanyte. Subgroup F. Limonite rock. Var. a. Limonite shale. b. Oolitic brown ore. c. Reniform iron ore. d. Pea-iron ore. e. Bog-iron ore. Subvar. a. Black. b. Yellow. c. Sparry. G. Hematite rock. Var. a. Red iron-mould. b. Eeddle. c. Sparry red-ironstone. d. Specular iron. e. Topanhoacanga. H. Spherosideryte. Var. a. Black band. J. Minerals occurring as rocks (see page 17). Var. a. Asphalte. b. Pyrite. c. Cinnabar. d. Boracite. e. Trona. /. Aragonite. g. Manganese ores. h. Rhodochrosite. i. Bole, j. Opal. h Fluorite. Z. Barite. m. Ankerite. n. Malachite, o. Melanite. p. Galmey. q. Zincite. T. Galenite. s. Stibnite. t. Arsenopyrite. u. Sulphur. v. Wavellite. w. Chalcopyrite. CLASSIFIED TABLE. 23 Group C. ROCKS PARTLY MECHANICALLY, PARTLY CHEMICALLY, AND PARTLY ORGANICALLY FORMED. Subgroup A. Laminated, or stratified coal. Var. a. Cannel coal. Subvar. a. Parrot coal. b. Horn coal. c. Torbanyte. 6. Splint coal. c. Culm. d. Bituminous shale. e. Carbonaceous shale. Subvar. a. Batt, or bass. b. Dauks. c. Kelve. d. Pindy. e. Slaty culm. B. Limestone. Var., a. Compact limestone. 6. Crystalline limestone. c. Marble. d. Oolyte. Subvar. a. Pisolyte. b. Dolomitic oolyte. e. Chalk. Subvar. a. Indurated chalk. b. Chalk rock. c. Pisolitic chalk. d. Glauconitic chalk. e. Ferruginous chalk, /. Calcsinter. Subvar. a. Travertine. b. Stalactyte. c. Stalagmyte. d. Rockmeal. g. Coral-reef limestone. h. Brecciated limestone. i. Limestone conglomerate, j. Rubbly limestone. k. Lithography te. I. Siliceous limestone. m. Cherty. n. Argillous. o. Arenaceous. 24 HANDY-BOOK OF EOCK NAMES. Var. p. Ferruginous. q. Bituminous. r. Stinkstone. s. Dolomitic limestone. t. Hydraulic limestone. Subgroup C. Dolomyte. Var. a. Granular. 6. Oolitic. c. Compact. d. Porous. e. Cellular. /. Concretionary. g. Brecciated. h. Kubbly. i. Ferruginous. j. Argillous. lc. Arenaceous. I. Siliceous. m. Cherty. n. Tuffose. o. Dolomitic sand. D. Marine drift. (See Class II., Subgroup JB, Var. c.) Class II. SUBAERTAL ROCKS. Group D. MECHANICALLY, CHEMICALLY, OR ORGANICALLY FORMED. Subgroup A. Coal. Var. a. Peat. Subvar. a. White turf. b. Brown turf. c. Black or Stone turf. d. Gas turf. 5. Lignyte or Brown coal. Subvar. a. Woody lignyte. b . Compact lignyte. c. Jet. c. Black coal or Steinkohle. CLASSIFIED TABLE. 25 Subvar. a. Caking coal. b. Non-caking coal. c. Cherry coal. Var. d. Anthracyte. Subvar. a. Native coke. Subgroup B. Surface deposits and accumulations. Var. a. Boulder-clay-drift. Subvar. a. Calcareous. b. Argillous. c. Arenaceous. b. Moraine drift. Subvar. a. Calcareous. b. Argillous. c. Arenaceous. d. Rocky. c. Sand, gravel, and shingle. Subvar. a. Esker drift. b. Post-drift gravel. c. Beaches. ' d. ^Eolian drift. e. Shell sand. f. Berginehl. d. Guano. e. Soil. /. Meteoric drift. g. Ice. PAET II, Order l.INGENITE ROCKS. Class L GRANITIC ROCKS. typical rock of this class is a crystalline J- aggregate of quartz, felspars, and micas, nearly universally known as granite or granyte [Celtic gran, Lat. granum, a grain.]* There are, however, rocks called granite in which part of the mica is replaced by other minerals, sometimes to such an extent that the mica is only microscopically visible. Granite usually is a quaternary or quinary aggre- gate, containing, along with quartz, one or two fel- spars and one or two micas ; nevertheless, other minerals are often present, more especially pyrite and marcasite.f Some granites are undoubtedly intrusive, while others appear to be only in part intrusive, portions having been formed in situ; that is, having relations as to position with the associated rocks similar to those which now exist. Typical granites weather with a peculiar rough, rugged aspect. * In Cornwall granite formerly was called growan, from gronen, a grain. t Some of the granites that weather or disintegrate freely appear to have marcasite as an ingredient disseminated in minute grains throughout the mass. iNGENITE RO A. Intrusive Granite; Leinster Granite ; Oughterard Granite [intruded into the place it now occupies] . An aggregate of quartz and orthoclase with black and white mica ; pyrite and marcasite are often constituents ; while Haughton seems to believe that most, if not all, intrusive granites also contain albite. NOTE. Haughton finds the intrusive granites of Cornwall, Devon, Leinster, and Ulster, to contain " quartz, orthoclase, margarodite, and lepidomelane." He has also detected albite. Varieties in Composition. A. PYRITOUS INTRUSIVE, or HIGHLY SILICEOUS GRA- NITE. When pyrite or marcasite is a com- ponent, galenite and chalcopyrite often occur as accessories. a. Beresyte, Beresite. Pyritous highly siliceous granite containing gold. B. ALBITIC GRANITE (Dana). Containing albite as well as orthoclase. C. SCHORLACEOUS GRANITE. With tourmaline (schorl) in addition to the mica. In the highly siliceous or intrusive granite, as also in all granite, and some of the other ingenite rocks, are veins of segregation, which in the gra- nites generally form two distinct varieties. One kind appears as irregular veins, nests, or patches, that have no deep-seated source, but die out every way, often in very short distances. The other variety makes regular, often dyke-like, veins, from half an inch or less in thickness, to about two or three yards in width. These latter appear to have segre- gated from the deep-seated fluid or semi-fluid por- tions of the mass, and to have been forced up into c 28 HANDY-BOOK OF EOCK NAMES. the vacancies or the shrinkage fissures caused by the contraction consequent on the consolidation of the cooled portion or crust of the mass. The granite in such veins would necessarily be more siliceous than the granite mass through which they traverse, as basic rocks, although they melt at a lower tem- perature than the more siliceous, cool sooner and at a higher temperature, losing their heat much more rapidly. Consequently, it appears evident that the portions of a mass of granite which remain longest fluid ought to be more siliceous than the parts that cool first. The dyke-like veins of segregation are undoubtedly more siliceous than the rock which they traverse. Moreover, they are more compact, and finely crystalline. These latter peculiarities may, however, be due to the final rapid cooling when in the veins. NOTE. M'Farlane thus writes on the cooling of siliceous rocks : " The scoria of iron-furnaces are usually very acid, con- taining as much as sixty per cent, of silex. They generally fuse at a temperature of 1,450 C. As they flow out of the breast of the furnace, they may be observed to do so very leisurely, to be sluggish and viscid, but nevertheless to continue fluid a long time ; and even, in some cases, to flow out of the building in which they have been produced, before solidifying. On the other hand, slags from certain copper-furnaces, or from those used for puddling iron, are more or less basic, containing from thirty to forty-five per cent, of silica. A s they flow out they are seen to be very fluid, and to ran quickly, but they solidify much more rapidly than iron slag. Yet these basic slags fuse at 1,300 C., or about 150 less than the more acid slags. Those who have been accustomed to observe metallurgical processes will not find it difficult to conceive how a very siliceous slag might continue fluid at a temperature at which a more basic one might become solid." They often are more or less felsytoid; that is, have the aspect of a felstone or felsyte ; but they always contain mica as a constituent, although often INGENITE EOCKS. 29 only visible under' the lens or microscope. On account of their similitude in aspect to felsyte, also on account of their usual purplish reddish colour, Delesse and others erroneously call them " eurites," although they are quite dissimilar to the original eurytes of Daubuisson. Rose, on the other hand, describes a granite apparently identical with them, and calls it granityte, a name to which there seems to be no objection. D. GRANITYTE ; GJSANITITE (Rose). A compact finely crystalline rock, usually purplish or red- dish purple in colour. An aggregate of felspar (orthoclase), quartz, and mica. Black and white mica seem always to be present, but often in such minute flakes as to be only microsco- pically visible. Pyrite, and sometimes marca- site, are locally present. Granityte * occurs as veins in granite from mere lines to two or more yards in thickness. It seems to be allied to elvanyte or quartz -porphyry, hereafter described, as sometimes part of the quartz in the granityte seems to have crystallized out prior to the other constituents. Moreover, granityte nearly always weathers evenly like those rocks, and not with the rugged uneven surface, so characteristic of typical granite. Allied to the intrusive granite are rocks that to the naked eye seem not mineralogically granite, yet petrologically they seem to be part of the in- trusive granite, as they always occur associated * If granityte, as suggested, fills cracks and fissures in,, the granite, it and elvanyte must necessarily have cooled under somewhat similar conditions. Jukes has described some of the granitytes of the counties of Wicklow and Dublin, Ireland, as elvanytes. C 2 30 HANDY-BOOK OF ROCK NAMES. with it, into which they seein to merge, and it into them. They are as follows : E. FELSITIC GRANITE (King) ; FELSITE ROCK (Gotta). " A rock of compact texture, about the hardness of felspar, with dull or smooth con- choidal or fissile fracture ; colour yellowish, reddish, grey, greyish, or bluish, weathering white." Gotta. To the naked eye this rock does not appear to contain either mica or quartz; however, with a lens, both of these substances can be detected, but usually they appear to be sparingly and partially developed. F. GREISSEN; QUARTZITIC GRANITE. Apparently a crystalline granular aggregate of quartz and mica. Greissen occurs associated with the intrusive granite, and merges into it. Sometimes, indeed, there is felspar developed, but so sparingly and at such wide intervals, that it seems to be more an accessory than an essential of the rock. In some places even the mica seems to be absent, or in such minute particles as only to be detected by a micro- scopical examination. Structural Varieties. G. PORPHYRITIC INTRUSIVE, OR HIGHLY SILICEOUS GRANITE. In which crystals of felspar are largely and conspicuously developed. H. PEGMATYTE ; PEGMATITE [Gr. pegma, a hardened mass] . The second variety of the veins of segregation ; very coarsely and irregularly crystallized, the conspicuous constituents, according to Cotta, being " orthoclase, quartz, INGENITE ROCKS. 31 and silvery-white mica." Nevertheless, it usu- ally also contains more or less dark-coloured mica, also pyrite or marcasite, and locally tourmaline. Pegmatyte sometimes appears in large, well- marked veins, but more frequently it occurs in irregular veins, patches, and lentils, dying out in every direction. The dark-coloured mica, although the other constituents may be very coarsely crystal- line, usually occurs in minute scales, but not always. a. Graphic granite [Gr. grapho, I write]. A variety of Pegmatyte, in which the con- stituents are so arranged as to produce figures resembling written characters. b. Blumen granite. " The felspar assumes a form resembling flowering-stalks." Gotta. c. Plumose granite. The mica assumes a plu- mose form, like Prince of Wales's feathers. Jukes. The granites belonging to this type [intrusive granite] in general are not foliated; nevertheless Forbes mentions a " foliated granite " at Edisvand, Norway; of which he says : "No doubt could be entertained of its true eruptive origin." And my colleague, Mr. R. Gr. Symes, describes veins of a foliated granite which he observed N.E. of Castle- bar, in the co. Mayo, Ireland. In south-west Mayo, associated with very slightly metamorphosed rock, are wide dykes of foliated rock, some being typical gneiss (leaves of quartz, felspar, and mica), others hornblendic gneiss, while some apparently are formed of leaves of quartz, orthoclase, and amphibole. Not uncommon in the intrusive granite is a structure having an aspect somewhat like folia- tion; and yet it cannot be so classed, as the con- 32 HANDY-BOOK OF EOCK NAMES. stituents of the rock have no tendency to occur in leaves. Perhaps it may possibly be some kind of close, irregular, rudely parallel-jointed structure, induced during the cooling of the rock, somewhat similar to the structure called by Scrope " shrinkage fissures." This structure of the intrusive granite is scarcely perceptible in a hard specimen, but in rock masses it is conspicuous. Granites more or less due to metamorphism, having (for the most part) been altered into granite while in their present positions as regards the associated rocks (see note, page 7). These rocks appear to have been formed from previously existing sedimentary and igneous rocks. Those due to the metamorphisin of the sedimentary and of the basic-igneous rocks, are often very similar in aspect and composition, while some of the acid-igneous rocks have changed into granite some- what similar to the Intrusive Granite (A). B. Granite for the most part non-intrusive; Basic or Oligoclase Granite ; Scandinavian Granite [in part metamorphic] . Usually a crystalline aggregate of quartz, black and white mica, orthoclase, and oligo- clase. When typical, it is a quinary granite; how- ever it is very variable in its composition, which in part seems due to its metamorphic origin. Many minerals occur locally as adjuncts ; such as amphi- bole, titanite, ripidolite, pyrite, marcasite, &c., forming different varieties. NOTE. Haughton is of opinion that the normal constituents of this class of metamorphic granite in Ireland, Scotland, Norway, Sweden, and Finland, are Quartz, Orthoclase, Oligoclase, Mar- garodite, and Lepidomelane. INGENITE ROCKS. 33 Varieties in Composition. A. HORNBLENDIC GRANITE. An oligoclase granite, in which amphibole is a constituent. a. Titanitic Granite ; Furbogh Granite. b. Chloritic or Ripidolitic Granite. c. Tatcose Granite. d. Epidotic Granite. With amphibole titanite sometimes occurs, and this variety has been called Furbogh Granite, from a district in the county Gal way, Ireland. In places ripidolite, talc, or epidote may be present with, or in place of, the amphibole, making vari- eties. The last-named mineral is supposed to be due to secondary formation. NOTE. Hornblendic granite by some geologists has been called " Syenitic granite/' This name, however, seems not only unscientific, but also inapplicable, as the rock is not an aggregate of granite and syenyte, but of granite and amphibole [hornblende], and it is to the latter mineral that the name is intended to direct attention. Chloritic granite and Talcose granite have erroneously been called " Protogene granite," also a most incor- rect name, as protogene (quartz-\- felspar -\-talc} is a constituent of neither. Furthermore, in general chloritic granite can have no relation to protogene, not containing any talc. B. GRAPHITIC GRANITE. With graphite in addition to mica. C. HEMATITIC OR FERRUGINOUS OLIGOCLASE GRANITE. With micaceous iron-ore in addition to the mica. I). PYRITOUS OLIGOCLASE GRANITE. Containing pyrite or marcasite, or even chalcopyrite, in addition to the other constituents. 34 HANDY-BOOK OF ROCK NAMES. Structural Varieties. E. PORPHYRITIC OLIGOCLASE GRANITE; Galway Gra- nite. Having one of the felspars developed in crystals, larger and more conspicuous than those of the other constituents. Generally, it is the orthoclase that is porphyritically developed; however, sometimes it is the oligoclase. It is the typical granite of county Galway, Ireland. F. GNEISSOID GRANITE; FOLIATED GRANITE; Gneissic Granite (Cotta). An oligoclase granite, in which there is more or less distinct foliation. Sometimes one of the felspars is porphyritically developed, when in general the mica does not curl round the large crystals of felspar, but the latter lie promiscuously about. a. Nodular Granite. Containing round or semi- angular pieces or nodules of a dissimilar granite or of a granitic rock. The inliers often are a hornblendic granite or a rock, like minette, or like a gneissyte, but they vary considerably. b. Lenticular Granite. A more or less gneissoid granite, containing lenticular patches or len- tils of granite or a rock, like a gneissyte or minette. The lentils sometimes occur closely together, at other times widely apart ; but in all cases the foliation of the rock curls round them. G. INTRUSIVE OLIGOCLASE GRANITE; Omey Granite. Very similar to the non-intrusive oligoclase granite ; but such minerals as amphibole, tita- nite, ripidolite, &c., only occur locally, as ac- cessories. It has been called " Omey granite," from an island on the west coast of Ireland. Besides the varieties mentioned above, others INGENITE ROCKS. 35 might be named, but those given seem to be the most important. Veins of segregation occur in the oligoclase granite. Their composition appears very similar to the veins of segregation (granityte] that occur in the highly siliceous granite, being of a more or less siliceous nature. There are also irregular veins, nests, and lenticular patches, sometimes of con- siderable size, of a rock answering Cotta/s descrip- tion for the rock called Pegmatyte. The Pegmatyte found associated with the non-intrusive oligoclase granite is, at least in some instances, due to the metamorphism of irregular felspathic veins and len- ticular patches that existed in the metamorphosed sedimentary and irruptive rocks prior to their being changed into granite. Basic igneous rocks may be metamorphosed into rocks very similar to the Basic or oligoclase granite, or its varieties; and the Acid or highly siliceous igneous rocks may change into a rock like the finer varieties of the Intrusive or highly siliceous granite (A) ; while the basic felstones (Euryte and such rocks) may be altered into more or less hornblendic or chloritic, or even talcose granite. H. GEANITIC FELSTONE. A fine, more or less even- grained aggregate of quartz, felspar, and mica. In some varieties the felspar seems always to be orthoclase ; the mica may be black or white, often both. Part of the mica may be replaced by amphibole or ripidolite. They weather neither like a true granite nor yet like a felstone, having a characteristic weathering of their own, partaking of the nature of both. Granitic felstones probably are metamorphosed felstones. They are often banded, the lines some- 36 HANDY-BOOK OF EOCK NAMES. times being parallel, or nearly so, to the walls of the dykes, but at other times they are oblique. The bands are due to thin zones of different colour or texture, perhaps also of composition. In these bands,, or between them, there is on rare occasions a structure like foliation. All the metamorphosed igneous rocks are more or less granitoid, in accordance with the intensity of the metamorphism that has acted on them and the associated sedimentary rocks. C. Protogene [Gr. protogenes, first formed ; the rock, when first discovered, being supposed to be the oldest] . A granitoid rock ; a crystalline aggre- gate of quartz, felspar, and talc. Protogene, although not a true granite, seems allied to those of the Oligoclase type (B) . The name is said to have been given originally to a metamor- phic rock, but its original signification appears to have been lost, for Gotta thus describes it : " A granite which contains talc or chlorite, or decom- posed mica, instead of the usual mica." This is an erroneous definition, for if it contains either mica or ripidolite instead of talc, it cannot be Protogene.* However, Gotta would appear not to be the only geologist or petrologist who has found this rock a stumbling-block ; as Haughton, after examining numerous specimens of the so-called Protogene from the Alps, states that most of them " contained not talc, but dull mica or ripidolite, or some kindred mineral/-' If a rock contains mica in addition to talc, or ripidolite in place of talc, it cannot be pro- togene, but is, in the one case, Talcose Granite, and in the other, Chloritic or Ripidolitic Granite. * Some basic felstones, when metamorphosed, appear to be true protogene (quartz-(-felspar-|-talc). INGENITE EOCKS. 37 The formation of granite is not fully understood ; yet I cannot but believe that while some are un- doubtedly intrusive, others have been formed by extreme metamorphic action. However, between the two extremes there is a rock (previously men- tioned and described as Intrusive oligoclase granite) that partakes of the nature of both, having con- stituents very similar to the ordinary oligoclase granite, while it is intrusive, like the highly sili- ceous granite. This at first may appear an ano- maly ; nevertheless it seems capable of a simple explanation. All authorities infer that granites were formed at a considerable depth beneath the earth/s surface, under pressure, by extreme heat. They cooled and consolidated, more or less gradually, long previous to coming near, or being exposed at the surface of the earth. Rocks, under the above conditions, would melt more or less rapidly in accordance with the inten- sity of the heat to which they were subjected, the amount of pressure, and constituents of which they are composed. Moreover, the more acid portions would remain longer fluid, during refrigeration, than the basic (see page 28). If, while in a state of fusion, the heating action were to cease or begin to subside (either of which must at some time have happened), the rocks or strata affected would be in the following conditions : Part would be entirely fused or liquefied ; part would be semifused ; while the rocks adjacent to the latter would be only more or less altered. Of the latter class, the least altered rock would be represented by rocks belonging to the Schist series ; while the more altered rocks, according to the intensity of the metamorphic action, would form the Gneiss 38 HANDY-BOOK OF ROCK NAMES. series and the Gneissoid granite. The second class, or the semifluid rocks, would form the Oligoclase granite, or the Granite due to extreme metamorphism ; while the first class, or the completely fluid mass, would form the different intrusive or irruptive rocks. Of the completely fluid mass, part ought to find its way to, or close to, the earth's surface, and then cool under little or no pressure, forming the Plutonic and Volcanic rocks ; a portion would con- solidate between the source, the caldron, if it may be so called, and the surface of the earth, under more or less pressure, and form Elvanyte or Quartz- Porphyry, the granitic rocks next to be enumerated and described ; while the residue would consolidate in or near the caldron. The consolidation of the residue, that remained in or near the caldron or source, could scarcely have been simultaneous, as it is probable the outer or upper portion would consolidate sooner than the inner or lower part. Moreover the acid portion would consolidate slower than the basic part ; consequently there ought to be two distinct rocks forming, a more basic rock above, and a more acid or siliceous rock below. As the upper or more basic rock cooled and consolidated, it ought to shrink more or less, and thereby form cracks, fissures, and other vacancies, into which the underlying still fluid or semifluid matter would be squeezed ; therefore at any time prior to their final consolidation, part of the oligoclase granite or part of the highly siliceous granite might be forced up into and occupy all vacancies in the supercrescent rocks, and thereby form intrusive granite of one or both types (Intrusive oligoclase granite and Intrusive INGENITE ROCKS. 39 highly siliceous granite) ; subsequently, when the overlying rocks were denuded away, tracts, veins, &c., of these granites would be exposed. The above suggestions, if correct, give a solu- tion for the formation of the three different kinds of granite, Highly siliceous granite, Intrusive oli- goclase granite, and the Non-intrusive oligoclase granite. The Non-intrusive oligoclase granite would be represented by the semifluid portion that first consolidated ; the Intrusive oligoclase granite by the more basic portion of the fluid mass that was forced out of its normal position ; while the Highly siliceous granite would be the part that took longest to cool and consolidate. That granite must cool and consolidate under laws somewhat similar to the above appears highly probable, because when two or more granites come from one source, the last formed is more siliceous than the rock through which it breaks up, while the veins of segregation in the former are more siliceous than the parent rock in which they appear. D. Elvanyte (Jukes) ; Quartz-Porphyry ; ftuartzi- ferous Porphyry; Granitic Porphyry (Cotta), [Celtic, el or oily rock, and van or ban, white, so called from the white crust of the rock when weathered] . A granitic rock, having a granular or compact felsitic or felspathic. matrix, inclosing globules, blebs, and crystals of quartz, crystals of one or more felspars, with more or less mica or amphi- bole, ripidolite, and the like. Pyrite and mar- casite are often constituents. In many of the siliceous varieties, a considerable portion of the quartz crystallized out prior to the other minerals. The matrix may be siliceous (felsitic) or basic (fel- 40 HANi>Y-BOt>E OF EOCK NAMES. *! spathic), and of a gfeenish, greyish, brownish, blackish, bluish, ,..or : ' even yellowish colour: all of the yellowish, as also some of the blues, seem due to weathering. NOTE. Elvanyte naturally includes not only the quartz- porphyries, but also the syenytes (quartz+felspar+amphibole) of some British geologists. The free silica or quartz in the Elvanyte is for the most part in irregular blebs or globules, from minute specks to the size of a pea, or even larger. The quartz internally has a glassy, often radiated struc- ture, and externally on some, the crystal faces can be recognized, while others appear to be regular coated minute balls. The quartz is scattered through the mass, sometimes sparingly, but at other times so thickly as to give the rock a piso- litic aspect. Elvanytes, except some of the very granitic varieties, weather with the even flow- ing surface so characteristic of the Felstones, and not with the rough rugged aspect of granite. They often near the edge of large masses, at the walls of dykes, and in small branch dykes or veins merge into a rock in appearance identical with felstone : this compact rock is called by Cotta the Base or Mother-rock. The Mother-rock at dyke walls is rarely more than a few inches thick. Elvanytes being hypogene rocks, are never accompanied by tuff. NOTE. A true elvanyte is more crystalline at the centre of a dyke or mass than at the margins, while an elvanoid rock due to inetamorphism is more crystalline at the margins than in the interior, the change in the latter taking place from the outside inwards. INGENITE Varieties in A. FELSITIC and FELSPATHIC ELVANYTE. Bespec- tively a siliceous or a basic elvanyte, in which the quartz, mica, and other minerals are more or less developed. a. Orthoclasic Elvanyte. When the felspar is principally orthoclase. b. Oligoclasic Elvanyte. When the felspar crys- tals are principally oligoclase. c. R&ppaMvi Elvanyte. An elvanyte in which many of the orthoclase crystals (often pink or flesh-colour) are inclosed in an envelope of oligoclase (often light green). In the Finland variety the orthoclase is generally in rounded masses inclosed in orbicular en- velopes of oligoclase. B. QUAETZITIC or SILICEOUS ELVANYTE. Having a large percentage of siliceous matter. G. MICACEOUS ELVANYTE. Having a large percent- age of mica. NOTE. These rocks would be called " mica traps " by some authors. (See Mica Trap, page 48.) D. PYRITOUS ELVANYTE. Having a large percent- age of either pyrite, marcasite, or chalco- pyrite. E. HORNBLENDIC ELVANYTE. When typical, a gra- nitoid rock, an aggregate of quartz, felspar, and amphibole, usually with some pyrite or mar- casite ; it however graduates into more or less compact varieties. Varieties in composition are, a. Micaceous ; b. Ohloritic ; c. Eelspathic ; d. Pyritous ; respec- 42 HANDY-BOOK OP EOCK NAMES. tively, as different minerals give a marked character ; some structural varieties are gneissoid. NOTE. Some authors would call hornblendic elvanyte and its varieties " syenyte." Part of a mass may be a true syenyte (am^MoZe+orthoclase+quartz), but in general the rock con- tains two felspars. F. CHLORITIC OK EIPIDOLITIC ELVANYTE. Having ripidolite replacing most or all of the mica or amphibole. Structural Varieties. G. GRANULAR ELVANYTE. With a matrix somewhat resembling granite; but distinct crystals of one or more felspars, with globules, blebs, and crys- tals of quartz, flakes of mica, or crystals of amphibole, are separately and prominently de- veloped. In one variety ripidolite replaces the mica or amphibole. H. COMPACT ELVANYTE, or PONTELLARYTE. The ma- trix is more or less compact throughout, form- ing a paste, often dark-coloured. It contains separate crystals, globules, or flakes of one or more felspars, amphibole, quartz, mica, or ripidolite. I. GNEISSOID ELVANYTE. Elvanyte with a struc- ture that seems to be foliation, more or less well-defined. Some varieties are micaceous, others hornblendic ; while some may be chlo- ritic. ' Some gneissoid elvanytes may be me- tamorphosed igneous rock. J. GRANITOID ELVANYTE. For the most part an aggregate of quartz and felspar, with mica, or ripidolite, or amphibole. Part of the matrix appears as a sort of paste, while some of the INGENITE EOCKS. 43 quartz occurs in globules, blebs, or irregular crystals, having crystallized out prior to the other minerals. Most granitoid elvanytes weather more like a felstone than like a granite ; some, however, do not. At the walls of dykes or masses they often merge into a more or less compact rock " The Mother-rode, or Base," of Cotta. Granitoid elvan- yte seems to be the passage-rock between granite and elvanyte. K. PYROMERIDE, or BALL ELVANYTE, Ball Porphyry . " This rock, in addition to the usual quartz crystals, contains balls of felsite (either small and numerous, or large and isolated. The small balls are frequently marked internally with radial streaks. The interiors of the larger ones are usually split after the manner of sep- taria, or they contain a geodic cavity). The clefts or cavities in the balls are wholly or partly filled with hornstone, chalcedony, agate, quartz, amethyst, calcite, fluorite, &c. &c.' } Cotta. Class II. PLUTONIC EOCKS. THIS name (from Pluto, the god ofs the infernal regions) has been given to the rocks that at one time were buried beneath the earth or ^ea, as dis- tinct from the Volcanic, or those that are thrown up and consolidated on the present surface of the earth. The Plutonic rocks were irrupted or in- truded, and consolidated at or near a former surface of the earth, or at the bottom of a sea or lake, under, comparatively speaking, little pressure; but subsequently they were covered by successive 44 HANDY-BOOK OF ROCK NAMES. deposits of "Derivate rocks." As they are not "hypogene rocks/' they have their tuffs, agglome- rates, and other mechanically-derived associates, with which they may be interstratified, as also with any class or variety of derivate or sedimentary rock. In Nature there are no hard divisional lines be- tween different kinds of rocks, more especially ingenite rocks; therefore the Plutonic rocks, on one hand merge into Granitic rocks, and on the other into Volcanic rocks. A boundary between the Granitic and Plutonic rocks can be defined, as the first are hypoo^ene, while the latter are not ; but the difference between the Plutonic and the Volcanic rocks is much more vagrue, we only knowing that the latter are intrusive rocks, erupted and consolidated at the present surface of the earth, while the former were formed in ages or geological periods long past, and subsequently were covered up by accumulations of strata that are now in part removed by the force of denudation, thereby bring- ing them again to the surface. E. Felstone, Felsyte, or Felsite [Ger. felspath, rock spar] . A compact or granular, or splintery quartz- itic felspathic rock often porphyritic or quartzose; sometimes micaceous, or hornblendic, or ripidolitic; pyrite or marcasite, and sometimes chalcopyrite, may occur as constituents. The Felstones, or Felsytes, include all the highly siliceous plutouic rocks, and are for the most part a felsitic compound. Various minerals, however, are locally ingredients, forming numerous subgroups and varieties. Felstones, or Felsytes, usually weather in flowing surfaces with even outlines. They are, however, affected by different structures. Some are homogeneous ; in some there is a platy arrange- INGEN1TE KOCKS. 45 ment, rudely parallel to the walls of the dykes ; while in others, sometimes, however, associated with the platy structure, is a spheroidal or concretionary arrangement. The platy structure may be due to the rock cooling in thin sections, or nearly vertical layers ; or perhaps, as suggested by Scrope, to the differential motion of the vesicular and non-vesicular portions of the cooling rock. The spheroidal or concretionary arrangement seems always to occur near the end of a dyke, and may be due to the cooling when the rock was in its last stage of mo- tion : Phillips, in his description of " Vesuvius/' figures and describes a similar structure in some of the dykes of lava belonging to that volcano. In other felstones, or felsytes, there are lines cutting obliquely across ; while in some is a rudely columnar structure, except that the join,t-planes are as often oblique as perpendicular to the walls of the dykes. Associated, in places, with the last-named is a very irregular platy development between the joint-lines usually perpendicular to them, but often more or less oblique. The minerals most commonly appearing in Fel- stone or Felsyte, are crystals of orthoclase, oligo- clase, pyrite, marcasite, and amphibole, blebs or crystals of quartz, and flakes of black and white mica, and ripidolite. The quartz globules vary from minute particles to the size of a pea. A. PETROSILEX (Brongniart) [Lat. petra, stone, and sileXy flint, on account of the hard matrix and flint-like appearance of the rock], Felsyte, or Felsite. The type rock of the Felstones. A compact or granular, hard, siliceous felsitic rock; a granular mixture of felspar and quartz, in which, although fine-grained, the miners 1 D 2 46 HANDY- BOOK OF EOCK NAMES. constituents do not merge into one another, but are recognized by the eye, with or without the help of a magnifying-glass. Petrosilex is greyish, greenish, purplish, or bluish in colour; when yellowish or reddish, the colour seems due to weathering. Some are splintery, but usually they have from an uneven to a con- choidal fracture, and are translucent or sub- translucent. Some have a porcelanic, others a saccharoid aspect. a. Felstone glass ; Pit'-listone felsyte* " The principal mass is homogeneous ; of vitreous pitch-like appearance ; conchoidal fracture ; resinous lustre ; translucent at the edges, and very variously coloured.-" Gotta. b. Ribawed petrosilex ; Striped, or ribanecl felsyte, with bands of different colour, texture, and sometimes composition alternating. In some varieties the rock splits into plates along the riban. J5. QUAETZITIC Or QUAKTZOSE FELSTONE, Or FELSYTE ; QUARTZIFEROUS FELSTONE. A. compact felsitic mass, inclosing crystals or crystalline grains of quartz. Of quartzitic felstone there are different varieties; some due to composition, others to structure. The compact matrix consists principally of fel- spar, and of it Cotta. says : " Probably orthoclase; its proportion of silica is, however, too high even for orthoclase, and it is therefore probable that some quartz is intimately combined with the fel- spar." The colour of the matrix is greyish, greenish, purplish, or bluish, with the surface * Pitchstone felsyte must not be confounded with the vol- canic rock. INGENITE ROCKS. 47 weathering a dirty white; when the rock is yellowish or reddish, the colour seems due to se- condary action. The texture of the matrix varies considerably : sometimes it is compact like horn, with a smooth conchoidal fracture ; at other times it is granular, or saccharoid, or splintery. Usually it is compact, with a fracture from semiconchoidal to uneven, but sometimes it is vesicular or amyg- daloidal. Varieties in Composition. a. Oligoclasic quartzitic felstone ; b. Micaceous; c. Hornblendic ; d. Ckloritic, or Ripidolitic ; e. Pyritous, according to whichever mineral gives a character to the rock. The micaceous varieties graduate into Minette, while other varieties graduate into Felsitic elvanyte. Structural Varieties. f. Striped, or -Ribaned quartzitic felstone. Thin layers of somewhat dissimilar texture; hence the fracture appears to be striped like a riban, and the rock splits more easily in the direction of those layers than across them. g. Varioiitic, or Spotted quartzitic felstone, con- taining in the matrix worm-shaped spots, or blotches of different colour, texture, and usually of composition. In the latter case the rock weathers into pock-marked, or ovate hollows. G. MINETTE, MICACEOUS FELSTONE, or FELSYTE. A more or less felsitic or felspathic rock, contain- ing much mica, and sometimes distinct crystals of orthoclase or oligoclase, or amphibole. a. Fraidronyte Fraidronite. " A greenish fels- pathic principal mass combined with a greater 48 HANDY-BOOK OF ROCK NAMES. or less quantity of mica. Pyrite and quartz occur as accessories." Gotta. NOTE. MICA TRAP. If the grouping of some recent writers were followed, the subgroup just described, and all other highly micaceous rocks, should here be introduced and described as Mica traps. Under this name, however, have been included "micaceous elvanyte," "micaceous felstone or minette," "mi- caceous euryte," " micaceous diabase or kersantyte," " micaceous dioryte or kersanton," " micaceous melaphyre," "micaceous do- leryte," and many micaceous varieties of the above subgroups ; rocks that are quite dissimilar, except that mica is largely deve- loped in each. Mineralogically, such a group may exist, but geologically or petrologically it does not, for the different rocks which must be included under the name are varieties or sub- groups not only of quite distinct groups, but also of distinct classes, for under it would be included granitic, plutonic, and volcanic rocks. Such a group will not be introduced into this Manual, but each micaceous rock will be found described in its natural group and place. _D. EURYTE, or EURITE [Gr. eureo, to flow well or easily] . A compact or granular felspathic rock, occasionally showing glistening specks of quartz in the mass, usually purplish or greenish in colour ; may be vesicular or amyg- daloidal ; when heated before the blowpipe in thin pieces, it fuses with greater or less fa- cility. It is often columnar. In A.D. 1817 Daubuisson proposed the name Eurite for the basic felstones, on account of their fusibility. This name was afterwards, however, misapplied by Delesse and others, who called Granityte (veins of segregation in granite), by Daubuisson's name, apparently mistaking the rock, on account of Granityte being in colour and aspect somewhat similar to Euryte .* * A Granityte to the eye may appear the same as a Petro-silex or a Euryte, but if carefully examined will always be found to INGENTTE ROCKS. 49 Subsequently Naumann has proposed for Dau- buisson's Euryte the name " Porphyrite/' and Cotta advocates its adoption. It however seems to be a most objectionable name, as many authors use the term synonymously with porphyry.* More- over, the name refers to a structure which is not an essential feature of the subgroup, or, to quote Cotta, " The name of Porphyrite refers to a texture which is not an essential feature of these rocks, because the Porphyrites are not always in fact porphyritic." NOTE. Intermediate between the highly siliceous felstones, orfdsytes, and the whinstones, are rocks that partake more or less of the nature of both. These intermediate rocks Jukes and other British geologists seem to class with the basic rocks under the general name of Greenstone ; r f a name derived from the prevailing colour of the rocks, as even the purplish varieties have a green tinge, or merge into a green. One reason for this classification seems to be, that all the rocks included, fuse with greater or less facility before the blowpipe. Within the last few years there appears. to be a reaction among some of the British geologists, who seem inclined to go to the other extreme, and place not only the eurytes, but also all the micaceous dole- rytes, diorytes, and diabases in the Felstone group. This is evidently erroneous, as the latter rocks ought to be put with the basic rocks : or they and the eurytes should be placed in an intermediate group (called Hybrid rocks by Durocher) between the highly siliceous and the basic plutonic rock. Varieties in Composition. a. Orthoclasic euryte ; b. Qligocl&sic ; c. Mica- ceous ; d. Hornblendic; e. Chloritic, or Ripi- dolitic ; f. Quartzose. contain minute flakes of mica and a granular structure, never having the compact or semivitreous appearance characteristic of a Euryte. * Its advocate, Cotta, seems to use it in this sense. t Jukes, in his Manual, mentions that there are u interme- diate rocks," but he does not name them. 50 HANDY-BOOK OP ROCK NAMES. The ortlioclase and oligoclase appear as crystals, changing the rock into a Porphyry ; the micaceous variety by some would be called a Mica-trap, and in the quartzose variety the quartz appears in blebs, globules, and crystals. Structural Varieties. g. Euryte porphyry ; h. Amygdaloidal euryte; i. Vesicular ; j. Compact ; k. Slab or flaggy euryte ; and I. Cleaved ; according to the structure that gives a character to the rock mass. The compact varieties have a conchoidal or sub- conchoidal fracture, while some of the cleaved rocks make a coarse roofing slate. Structural Varieties of the Feist ones. E. COMPACT FELSTONE, or FELSYTE. Typical fel- stone or felsyte (see Petrosilex). F. GRANULAR FELSTONE, or FELSYTE. G. FRIABLE, or MEALY FELSTONE. A more or less fissile, or friable felstone ; usually of a pale greenish or greyish colour; tough, but splits easily ; a mealy or scaly aspect ; often has a soapy feel, showing a transition into Steatyte. This rock is undistinguishable in aspect and com- position from some of the fine mealy Felstone tuff. It may possibly be a true tuff, but as it occurs in dykes and intrusive masses, and often graduates into a compact felstone, it is here described. H. RUBBLY or SHINGLY FELSTONE ; THICKLY-JOINTED FELSTONE. So traversed by three or more re- gular or irregular systems of joint-lines, that the rock break sup into rubble or angular shingle, and is incapable of being quarried in large pieces. INGENITE EOCKS. 51 J. CLEAVED or SLATY FELSTONE. With cleavage- planes, sometimes so distinct that the rock splits into slates, but rarely into " Eoofing slate." /. FOLIATED or SCHISTOID FELSTONE ; SCHISTOSE FELSTONE. A fissile^ felspathic rock, composed of leaves of felspar, with mica or amphibole, or ripidolite ; sometimes with a little quartz. NOTE. Rocks very similar both in aspect and in composi- tion are found among the metamorphic igneous rocks. Never- theless it may be possible that some felstones are so constituted that on solidification their constituents arrange themselves in leaves. At Barna, co. Galway, Ireland, breaking up through the porphyritic oligoclase granite, are dykes belonging to this subgroup that apparently are newer than the time at which the general metamorphism of the associated rocks took place. K. GRANULYTE, or GRANULiTE. " A fine-grained to compact fissile compound of felspar and quartz, usually with some mica." Gotta. NOTE. Granulyte, although allowed to remain provisionally among the Felstones, m*y properly belong to the metamorphic igneous rocks, and be a felstone into which a fissile structure has been introduced by metamorphism. Some of the metamor- phic igneous rocks hereafter to be described seem to be iden- tical with the granulite of Gotta. L. FELSTONE or FELSYTE PORPHYRY; PORPHYRY; ORTHOPHYRE. Felstone, or Felsyte, contain- ing distinct and numerous crystals of one or more felspars. a. Amygdaloidal (Or. amygdalon, an almond); b. Vesicular. If the felsitic or felspathic matrix is full of cavi- ties, the rock is called vesicular, while, if it contains crystalline secretions filling the original cavities, it is called amygdaloidal. 52 HANDY-BOOK OF EOCK NAMES. FelstoneSj or Felsytes. supposed to be metamorphosed. Metamorpliic action as yet has not been properly explained or understood. It cannot be denied that derivate rocks may be altered into schist and gneiss ; yet many authorities seem to doubt that igneous rocks could be altered by the action that meta- morphosed the others. That the latter have some- times been altered, seems not only probable but also absolutely necessary, for the following reasons : There are derivate rocks of all ages, which have their associated igneous rocks. Such derivate rocks, except, however, those of the most recent age, are often metamorphosed; the metamorphism being clearly normal (to use Delesse's expression), i.e. not the result of the intrusion of the igneous rocks, although, as is often evident, effected after that intrusion. The agents which have prevailed to metamorphose the containing derivate rocks must unquestionably have attacked the contained igneous rocks, and that they have sometimes succeeded in altering them also more or less, seems clear from the circumstance, that the igneous inliers just men- tioned are often different from any of those that occur in unmetamorphosed sedimentary rocks ; which circumstance cannot be regarded as merely accidental. In some localities, such as West Galway and Mayo. Ireland, there appear to be data for the above suggestions. In these places it has been observed that associated derivate and igneous rocks appear to have been acted on in similar ratio, as expressed in the following table : * * This table only records changes that have been observed, not, however, all the changes rocks are capable of. The first stages of metamorphism of the Whinstones are so various, that it is hard to give a general name foi the rocks. INGENITE EOCKS. 53 THIRD STAGE METAMORPHISM. | 'M *i * 2 S S 2 be ^ bJO b 1 -2 - . .-I ! J .1 .1 | .l| | f| 1 OOOK O O co W tc D : ~^ ^ . - 1 H w ^ rh | - 1 1 * Q. C^ i ^ ^ i g - SECOND STA( METAMORPH | I| S 1 I 1 O O *rj oj -M F S c N 2 >s 2 s : -^ : : : i M : : : : : : FIRST STAGE- METAMORPHIS3 H J 1 J 11-2 g 4 1 ^^ t 'S ^^ 3^ g n3 m * ^ S ^^ l-2^.2 ffi 3^ 3 9 "fl 1* :" -2 "> 1 s 1 5* f 1 1 1 8 I ^O 3 ^ P^ f^HC/2P C/^O O2 . . UNALTERED ROCKS. (D *H g ^ ^ -1 ^ ri ^ ^ J 1 1 1 1 ^1 I 5 | 1 Hi t 1 IS | I 1 1 c/^C^coE/Qc/ii P^S f^ H^ 54 HANDY-BOOK OF EOCK NAMES. M. GNEISSYTE Or GNEISSITE; GNEISSOID FELSTONE. A crystalline fissile aggregate of quartz, felspar, and mica, more or less foliated; always occur- ring in dykes or intrusive masses, associated with gneiss or schist. NOTE. Apparently this rock is the same as the rock described by Cotta, and called Eed Gneiss. Gneissyte generally does not occur among sedi- mentary rocks in the first stage of metamorphism * (Schist series), but among highly metamorphosed sedimentary rocks (Gneiss series) dykes and masses of it are often found. Varieties in Composition. a. Quartzose Gneissyte; b.Felsitic; c. Micaceous ; d. Hornblendic ; e. Syenyte Gneissyte ; f. Chloritic or Ripidolitic; g. Talcose Gneissyte. Varieties d, e, f, and g are probably metamor- phosed eurytes. The difference between d and e is, that the former contains mica, in addition to amphi- bole, while in the latter there is only amphibole. Structural Varieties, li. Porpliyritic, and i. ScMstoid. The latter variety splits easily along the planes of foliation, on account of one of the constituents, usually the mica or the quartz, being only very sparingly developed. It is the passage rock between gneissyte and schistoid felstone. N. SCHISTOID FELSTONE or FELSYTE. A fissile ag- gregate of felspar and mica; generally a little * For the degrees of metamorphism of the derivate rocks see pages 37 and 76. INGBNITE EOCKS. 55 quartz is present, but in such small quantities as to seem more an accessory than an essen- tial. The rock mass is more or less foliated. Some schistoid felstones have an unctilous feel, and change by pseudomorphic action into steatyte schist, or even steatyle. NOTE. The foliation in the metamorphic felstones seems to follow conspicuous structures in the original rocks. Some normal felstones are amorphous, others have a spheroidal or platy struc- ture, while some are cleaved. In the amorphous felstones there are often lines apparently due to viscid fusion, while in the platy felstones the lines are parallel, or nearly so, and at other times oblique to the walls of the dykes. In the metamorphic felstones very similar structural peculiarities can be found ; in some there is little or no foliation, but the rocks are banded (see Granitic Felstone, page 35), while in some there is well- marked foliation, either parallel or oblique to the walls of the dykes, or spheroidal. Schistoid felstones may be named after conspicu- ous minerals locally essential ; they may be quartzose, or f el spathic, or micaceous, or hornblendic, or stea- titic, &c. &c. F. Whinstone;* Greenstone. A crystalline aggre- gate of felspar with either pyroxene, amphibole, or uralite. With these minerals, in forming subgroups and varieties, are associated ripidolite, mica, pyrite, marcasite. Under the group of Whinstone are * The term Whinstone has been adopted in place of Green- stone, as the latter has different significations, according to the authority by which it is used. Jukes and many other British geologists include under that name not only the basic plutonic rocks, but also all the basic felstone, especially when of a green colour. Cotta includes under this name Dioryte and Diabase. Brongniart confines the term to Dioryte, while Naumann restricts it to Diabase. Whinstone seems to be a nearly universal name in England, Ireland, and Scotland, the only objection to it being that in places it is also applied to the basic volcanic rocks. 56 . HANDY"-BOQK OF EOCK NAMES. included all the very /basic Plutonic rocks. They are usually dark^cploured, greenish or blackish ; however/ a. few' are light-coloured. The whinstones are often vesicular or amygdaloidal, and have their associated tuffs, with which they are often inter- stratified. A. DOLERYTE [Gr. doleros, deceptive]. A tough aggregate, principally a mixture of felspar and pyroxene. Nearly always of a dark colour. a. White-rock (Jukes). A doleryte of a nearly white colour, found associated with coal in Staffordshire and elsewhere. The dykes of " white-rock " can be traced into masses of ordinary dark-coloured doleryte. b. Aphanyte- doleryte ; Basalt. Very compact ; often called " Basalt;" the latter name, how- ever, ought to be only used for a variety of volcanic rocks. B. MELAPHYRE. A crystalline aggregate of felspar and pyroxene, with or without amphibole ; of a dark colour, greenish, brownish, or blackish, with more or less resinous lustre ; may be compact, porphyritic, vesicular, or amygdaloidal, and often contains specks of opal or quartz, also zeolites. Before the blowpipe it fuses readily ; fracture uneven. Varieties in Composition. a. Eukryte, or Eukritfi. A crystalline granular aggregate of anorthite and pyroxene, occa- sionally with some olivine, amphibole, and epidote ; the latter mineral being due to decomposition. Peridoli/te. A sub variety in which olivine is always present. INGEN1TE EOi b. Magnetic Melaphyre ; abrt*tf$J mS^nfeifilJeVas a constituent. This roca^^j^ajw^^b^ dis- tinguished from ma gnem^mwas^^s the magnetic constituent of the latter is pyrrho- tite. c. Micaceous Melaphyre. The mica often is in considerable quantities. Structural Varieties. d. Porphyritic, containing felspar crystals; e. Amygdaloidal; f. Vesicular; &ndg.Variolitic, having spots of a different colour and texture, also perhaps of composition. C. PYROXENYTE (Dana).~ A compound of pyroxene and orthoclase. D. DIABASE. A crystalline granular aggregate of felspar, pyroxene, and ripidolite ; colour usually greenish or purplish. The felspar is either oligoclase or labradorite, and frequently the latter. The pyroxene is diallage, and rarely ferruginous. The ripidolite is generally green, and in subordinate quantities ; it is often only distinguishable with difficulty, from being in intimate admixture with the dial! age. Varieties in Composition. a. Pyroxenic, or Augitic Diabase, having nume- rous and well-developed crystals of pyroxene, which, when weathered, give the rock a spotted appearance like a toad. b. TIralitic Diabase, with numerous and well- developed crystals of uralite. In some subvarieties part of the pyroxene in the matrix is replaced by uralite. This rock, also, when weathered, has a spotted aspect. 58 HANDY-BOOK OF ROCK NAMES. c. Labradoritic ; d. Oligoclasic ; e. Magnetic, con- taining pyrrhotite ; a micaceous subvariety, weathers freely into a magnetic sand ; f. Kersantyte "(Delesse), or Micaceous ; and g. Calcareous. " In a fine-grained or compact matrix of diabase rock are found small rounded grains of calcite, which do not apppear to be the fillings- up of cavities." Cotta. Structural Varieties. If diabase contains numerous and well-developed crystals of felspar, it is called h. Porphi/ritic ; if there are roundish concretions of any mineral, it is called i. Amygdaloidal ; while it is j. Vesicular, if there are open cavities ; fe. Variolitic (" In the prin- cipal mass round concretions occur of a compact or radial-fibrous, or concentric felsite (labradorite) " Gotta) ; and 1. Aphanyte, or Compact Diabase. E. GABBRO; GRANITONE; DIALLAGE EOCK " consists of labradorite or saussurite, and diallage, or smaragdite irregularly combined; also some- times all of these minerals together. It is very coarse-grained, fine-grained to compact, some- times slaty or spotted." Cotta. Some Diallage rock, such as that of the Lizard, Cornwall, is a metamorphosed igneous rock. a. Euphotide. . Aphanyte [Gr. aplianes, unmanifest] , or Ana- mesyte (Jukes). A compact homogeneous variety of dioryte, without distinct grains. Some dioryte-aphanytes are said to have as their felspar, orthoclase ; in which case they are not, pro- perly speaking, a homogeneous variety of Dionjte, but a homogeneous variety of Syenyte. c. Kersanton (Riviere), Micaceous Dioryte. Con- taining a great and conspicuous quantity of mica. NOTE. The highly micaceous diorytes, similarly as the highly micaceous melaphyres and diabases, would be classed by some geologists among the " mica traps." d. Napoleonyte, or Orbicular Dioryte. A local variety, consisting, according to Delesse, of a combination of anorthite, blackish-green amphibole, with some quartz. The anorthite and amphibole form orbicular concentric layers round a kernel, each mineral forming different layers of alternate light and dark colour. G. SYENYTE, SYENITE. A crystalline aggregate of orthoclase and amphibole, with or without quartz. The quartz appears to be more an accessory than an essential. NOTE. Some syenytes are undoubtedly metamorphosed igneous rocks, while others do not appear to have had such an origin. The name Syenyte has been given to various rocks. Haughton, Forbes, Cotta, Werner, and others describe it as a rock in which quartz is not a necessary ingredient; while Jukes, Dana, and INGENITE EOCKS. 61 others define it as an aggregate of orthoclase, am- phibole, and quartz. Some authorities erroneously class the hornblendic granites among the syenytes. Cotta says : u The orthoclase or inicrocline is usually the principal ingredient, and being in general red, it gives that colour to the whole rock. There are, however, syenytes whose orthoclase is nearly white. " In the syenytes of West Galway, Ireland, of metamorphic origin, the orthoclase is usually white. Varieties of Syenyte are, a. Quartzose, and b. Titanitic. Whinstones, or Greenstones, supposed to be meta- morphosed. H. HOENBLENDE EocK (Macculloch) . An aggre- gate of arnphibole, felspar (usually not ortho- clase), pyrite or marcasite, epidote, &c. &c. Some are so finely crystalline as to be nearly compact, while others contain crystals ofam- phibole, from one to four or five inches long. Hornblende rock may in places be schistose, or nodular, or concretionary. Some of the schistose portions of this kind of rock, from larconnanght, Ireland, have been proved by Forbes to be derivate rocks; consequently such portions must be meta- morphosed tuff. When Hornblende rock is nodular or concretionary, it may have spheroids from the size of a man's head to four or five feet in diameter, irregularly heaped up together, with the interstices filled with a schistose-looking stuff, that has a foliation rudely curling round the nodules; or the interstices may be occupied by a felsitic rock, or even with quartzitic stuff, or perhaps with two or more of these substances mixed together. E 2 62 HANDY-BOOK OF EOCK NAMES. Spheroidal or concretionary structure occurs in some whinstones, and Scrope calls particular at- tention to it, in some of the augytes of Central France. To such a structure in the original (un- metamorphosed) rock, some of that in the Horn- blende rock may possibly be due ; nevertheless, the greater portion is probably due to the broken- up parts of the flow [the. Friction-breccia of Cotta] that were rounded by attrition against one another; while the interstices were filled with the abraded or disintegrated portions of the rock, or by foreign matter washed into them by the water into which the flow was poured. This suggestion appears pro- bable, more especially when the typical rock merges into the nodular variety, and the latter, through agglomerate or conglomerate, into schist and gneiss. a. Actinolite Rock, or Glassy Actinolite Rock (Krantz). b. Tremolite Rock. Hyaline acicular crystals of actinolite or tremo- lite, respectively mixed with a felspar (usually not orthoclase), or numerous nests of crystals may occur in a hornblendic felspathic matrix. NOTE. Actinolite and tremolite rocks are liable to merge into ophyte, or one of the allied rocks, as all the magnesian amphiboles seem to have a tendency to change by pseudo- morphic action, partly or wholly into ophite, steatite, or such minerals. c. Hyperyte, or Hypersthenyte (see ante, page 59). d. Dioryte (see ante, page 59). e. Syenyte (see ante, page 60). e. Felso-syenyte, or Felsitic Syenyte, a variety of syenyte, in which the felspar (orthoclase) INGENITE ROCKS. 63 predominates to the nearly total exclusion of the amphibole and other minerals. f. Mico-hornblende Rock, or Micaceous Hornblende Rock. Black, bronze, or white mica occurs as an essen- tial. The flakes are sometimes of a considerable size, but more often they occur in small pockets or secretions. Usually they are regularly, although not very abundantly, distributed through the mass. A mico-hornblende rock is easily distinguished, as the mica decomposes more readily than the other constituents, and gives the rocks a pitted aspect, if the mica is in bunches or pockets ; while, if it is in large flakes, the weathered surface of the rock has often a somewhat graphic character, caused by the weathering away of the edges of the mica. Other varieties also have mica as an essential, scattered through the mass ; these latter are often more or less schistoid. G. Rocks due to Pseudomorphic Action, or to Wea- thering. Some of these rocks, as will be evident from 'their description, belong in part to Order No. II. (Derivate Rocks] \ as, however, they are products of the igneous rocks, it seems expedient to describe them altogether, A. OPHYTE, or OPHITE; SEEPENTINE. A compact rock, dull in fracture, with an unctuous feel. Colour dark green to blackish or brownish, reddish or variegated. Dana divides massive serpentine into Precious and Common Ophyte. The first ' ( is of a rich oil- green colour, of pale or dark shades, and translucent even when in thick pieces." The common ophyte is of dark shades of colour, and sub-translucent. 64 HANDY- BOOK OP KOCK NAMES. " The former lias a hardness of from 2'5 to 3; and the latter often of 4 or beyond, owing to impurities." Ophyte may originally have been either whin- stone or felstone. It weathers into an impure ferruginous meerschaum of a dirty yellowish colour, giving the rock a peculiar burnt or baked aspect. A variety is Ophi-hornblende rocky or a hornblende rock in which part of the felspar or part of the amphibole is changed into ophyte. B. STEATYTE, Soap-stone. An unctuous, soft, fissile, but, at the same time, tough rock, of a light greenish, greyish, or bluish colour. Ophyte and steatyte often occur together in intrusive masses or dykes, associated with steatitic felstone or ophi-hornblende rock, also with horn- blende schist or felsitic schist. Friable felstone, f els bone tuff, whinstone tuff, &c., may change into steatyte. Varieties are, a. Felspathic; b. Pyroxenic ; and c. Amphibolic. Steatyte, as formed from felstone or whinstone, may contain a large percentage of felspathic tuff, or of pyroxene or amphibole. C. EKLOGYTE, orEKLOGiTE. An aggregate of green smaragdite and red garnets. The smaragdite forms a finely crystalline matrix, in which the crystals of garnet are disseminated. It is often micaceous. Some varieties undoubtedly are pseudomorphs of hornblende rock. NOTE. Some of the fissile rocks, usually called Eklogyte, are metamorphic sedimentary rocks, and their description is given under the head of Smaragdite Schist (see page 93). The rock here described is an intrusive rock. INGENITE BOOKS. 65 D. EPIDOSYTE, EPIDOTE ROCK. An aggregate of felspar, amphibole, epidote, pyrite, or marca- site, &c. It occurs as dykes and intrusive masses, or as nodules and lentils in the meta- morphic rocks. E. KAOLIN, Porcelain Clay [Chinese, Kau-ling, high ridge, the name of the place where the clay was first manufactured]. A white, greyish- white, yellowish, sometimes brownish, bluish, or reddish, clay-like or mealy or compact substance, due to the decomposition of a very felsitic rock. Baron Von Richthofen has proved that kaolin was originally manufactured by the Chinese from Petrosilex; but though the name at first indicated an artificial felsitic clay, now the term has generally been adopted for a clay due to the decomposition of a felsitic rock. Kaolin sometimes occurs in dykes, but more often it seems to have a bedded structure, when it more properly belongs to the second order of rocks (D&rwate rocks) . F. FULLER'S EARTH. "A substance resembling clay, somewhat greasy, but not in the smallest degree plastic, but falling to pieces in water; usually of a yellowish-green colour ; is pro- bably a product of the decomposition of basic igneous rocks." Gotta. Fuller's Earth sometimes occurs in dykes, at other times, similarly to kaolin, it seems to belong to the Derivate rocks. G. MEERSCHAUM, SEPIOLYTE. Compact, with a smooth feel, and fine earthy texture. Colour greyish-white, or with a faint yellowish or 66 HANDY-BOOK OF BOOK NAMES. reddish tinge; opaque. An earthy hydratecl silicate of magnesia. NOTE. Ophyte weathers into an impure meerschaum. Dana points out that sepioly te, in Asia Minor, occurs " in masses in stratified earthy or alluvial deposits ; " and Cotta states it "forms separate beds, which are the result of a process of transmutation, probably of magnesite." H. MAGNESYTE. An aggregate of the carbonates of magnesia and iron. It may contain felspar, mica, quartz, chrome, nickel, &c. H. Tuff. Ingenite in part, derivate in part [Ital. tufo, Gr. tophos] . The mechanical accompaniments of the Plutonic rocks, consisting of the dust, powder, cinders, fragments, blocks, and other rock debris ejected during an igneous eruption. Sub- sequently these were more or less stratified by water or air, and afterwards consolidated by pres- sure, heat, or cement; or, perhaps, by two or more combined. NOTE. The name tuff was originally applied to the mechan- ical accompaniments ejected during an igneous eruption, but afterwards it was erroneously used for any porous vesicular stone, often a purely sedimentary rock, while the term ash was used to denote the true tuffs. Ash, however, is an objec- tionable name, as an ash is the residue of any substance left after that substance has been burnt ; while tuffs are never a pure ash, although portions of ash may form minor consti- tuents. Tuff may be used as the name for the mechanical accompaniments of the PJutonic rocks, and tufa for those of the Volcanic rocks (see page 75). Correctly speaking, no rock should be called a tuff unless the materials forming it were ejected in fragments from an igneous vent, and subsequently fell either on land or in water. In practice, how- ever, this distinction cannot always be followed, as many tuffose sandstones or tuffose shales, whose INGENITE KOCKS. 67 origin is mainly due to the abrasion and disinte- gration of ingenite rocks, are undistinguishable in aspect or composition from true tuff. Forbes has pointed out, that when outbursts of ingenite rock are forced or have flowed into the sea, they may be " at once broken up into a state of divi- sion, more or less fine, in proportion to the greater or lesser cooling power of the water mass in immediate contact, and may be spread out into beds by the action of the waves." Many rocks thus formed, although not true tuffs, are yet not only undis- tinguishable from them, but in some cases (except under the microscope), are also undistinguishable in aspect and composition from igneous rocks. Tuffs may be stratified or unstratified ; sometimes they even occur in dykes and pipes. As they, in part, are sedimentary rocks, fossils may occur in them. Varieties due to Composition. A. FELSTONE TUFF, FELSYTE or FELSTTIC TUFF. An aggregate of felspathic or felsitic parts usually more or less flaky or mealy; colour reddish, greenish, greyish, or bluish, weather- ing yellowish- white. Often very greasy to the touch, which appears to be due to particles or portions changing into steatite. As previously mentioned, portions of some f el- stones are very flaky or mealy in aspect ; these it is difficult, except when studied in situ, to dis- tinguish from felsyte tuff. Varieties are, a. Quartzose ; b. Calcareous ; c. Pyritous ; d. Cupriferous ; and e. Hema- titic. B. WHINSTONE TUFF, Basic or Greenstone Tuff. A greenish, reddish, purplish, or greyish-bluish 68 HANDY-BOOK OF ROCK NAMES. rock, from coarse to fine and compact ; often laminated, sometimes finely, at other times having alternate layers of fine and coarse mate- rials ; they may be conglomeritic or brecciated, when they often merge into Agglomerate. Varieties are, a. Hornblendic ; b. Pyroxenic; c. Ckloritic; d. Calcareous ; e. Pyritous ; f. Cupriferous ; and g. Hematitic. C. CALCAREOUS TUFF. Tuff cemented together by a limy or calcareous matrix. _D. ARENACEOUS TUFF. E. ARGILLOUS TUFF. These respectively contain a large percentage of sand and clay. Many of these rocks pro- bably are not true tuff, but are due to the disintegration of igneous rocks, the detritus being mixed with sand or mud. Some arena- ceous tuffs are cemented together by a siliceous paste. F. HEMATITIC or FERRUGINOUS TUFF. A reddish or yellowish ferruginous rock ; sometimes argillous, at other times arenaceous. It may merge into an earthy limonite. NOTE. Some varieties of the Indian rock called Lateryte, from Kutch, seem to be a variety of hematitic tuff. Very similar rocks are found associated with doleryre in Antrim, Ireland : both in Ireland and Kutch the rock may be steatitic. G. PYRITOUS TUFF. H. CUPRIFEROUS TUFF. Con- taining a large percentage of pyrite, marcasite, or chalcopyrite, so as to give a character to the rock. J. STEATITIC TUFF. A greenish, greyish, bluish, or reddish mealy or flaky rock ; having a greasy feel. It appears to be a pseudomorph. INGENITE ROCKS. 69 Varieties due to Structure. J. PORPHYRITIC TUFF. K. NODULAR, with its varieties, a. Concretionary, and b. Spheroidal. L. SHALY TUFF. Fine-grained, compact, and de- posited in thin laminse or layers. There are two varieties, a. Flaggy, when the layers are between half an inch and four inches thick, the rock easily splitting into tabular masses ; and b. Slaty, when there is a well-developed slaty cleavage. M. CONGLOMERITIC TUFF, PLUTONIC CONGLOMERATE. Tuff containing blocks and fragments of different kinds of rock. Its varieties are, a. Brecciated Tuff, or Plutonic Breccia, and 6. Plutonic Agglomerate. Variety a includes those rocks that contain an- gular blocks and fragments, while Lyell has intro- duced the term Agglomerate to designate those large irregular unstratified accumulations of blocks and detritus thrown up by igneous eruptions. Class III. VOLCANIC EOCKS. THE name of the class is derived from Vulcanus, the god of fire. They are eruptive or intrusive rOcks, brought up by vulcanicity, and consolidated near or at the present surface of the globe. They are necessarily accompanied by tufa and such me- chanically derived associates. NOTE. None of the rocks allied to the volcanic have been placed among the granitic rocks ; nevertheless, it appears highly 70 HANDY-BOOK OF ROCK NAMES. probable that some varieties of Liparyte (Trachyte porphyry' ought to be classed among the Elvanytes. Gotta says of the liparytes, which are granitoid in aspect, that in some cases it is impossible to distinguish between them and Quartz-porphyry (Elvanyte). " In these cases the only real difference consists in their geological connection with genuine trachytes or their petrographical transition into perlyte or pumice-stone." I. Trachytic group. Compact or granular, or splintery or cellular, crystalline felsitic or felspathic rock : some contain crystals of quartz, mica, and amphibole, or even pyroxene ; the whole either confusedly united or imbedded in a felspathic paste. Some are porphyritic or even granitoid. The Trachyte group embraces all the siliceo- felspatl;ic volcanic rocks. Among them are also included such transitional basic felspathic volcanic rocks as the Grey stones of Scrope, the Tr achy dole- rytes of Abich, or the Hybrid rocks of Durocher. A. KHYOLYTE, or RHYOJJTE. " A compact enamel- like, or vitreous matrix enclosing grains or crystals of sanidine " (rhyacolite), " oligoclase, mica, or even -quartz." Cotta. In Ehyolyte free quartz appears much more frequently than in common Trachyte ; while it contains no amphibole or pyroxene, or at least, those minerals are rarely found in it. From this it is apparent that Khyolyte is highly siliceous or felsitic Trachyte. a. Liparyte,OY Liparite; Trachyte-porphyry. "Is the name given to those rocks (prevalently felsitic and porphyritic with a compact matrix) which are geologically allied to the trachytes." Gotta. Liparyte has a compact felspathic matrix, con- taining crystals of felspar, and sometimes also INGENITE ROCKS. 71 mica or quartz. As a rule it is much richer in silica than the trachytes hereafter described. Cotta says it only very rarely and exceptionally contains some traces of amphibole. In some the matrix is compact and somewhat shining ; in others it is enamel-like, while in others it is dul]. They may be platy or vesicular or pumiceous. Usually light- coloured some are granitoid and undistinguishable except in their geological position and age from Elvanyte ; the latter variety ought probably to be classed among the Granitic rocks. As among the Plutonic rocks, so also among the Volcanic rocks, there must be passage-rocks into true granite; among the Volcanic, however, these cannot be so prevalent as among the Plutonic, as the latter rocks have been usually exposed by the force of denudation, while rarely do we find the roots of the more recent eruptions exposed. b. Perlyte, or Perlite, Pearlstone, Pearlstone-por- pJiyry. "An enamel-like matrix containing round grains, several of which are con- structed with concentric layers/" Cotta. Perlyte may be granular, or sphserulitic (with compact or radial striped felsyte balls), or porphy- ritic, or pumiceous, or vitreous (with resinous lustre), or argillaceous. c. Obsidian (so named after its discoverer, the Roman named Obsidianus) . Trachytic or volcanic glass. Obsidian may be compact, or a mere glass, or porphyritic, with sanidine crystals, and sometimes also mica plates, or sphserulitic, in which case it is a passage-rock into perlyte. d. Pumice, Vesicular Obsidian (Ital. pomice, akin 72 E^NDYrBuK OF ROCK NAMES. to spuma,' f roily,. Vesicular volcanic glass. Some y,ariqtie^' are so porous that they will float on water. e. Phonolyte or Phonolite Clinkstone (Gr. phone, sound, and lithos, stone). Compact, in places vitreous ; due to cleavage-surfaces of felspar; usually dark greenish-grey. Often platy in texture, and rings when struck with a hammer. Weathers with a whitish crust, similarly to many of thefelstoiies. Phonolyte may be compact, vesicular, flaky, variolotic, porphyritic, or amygdaloidal. B. TRACHYTE (Gr. trachys, rough). " A compound of sanidine, oligoclase (or even albite and labradorite), with some amphibole or pyrox- ene, and dark-coloured mica. A rough prin- cipal mass in which, as matrix, some of its mineral constituents are frequently distinctly and separately developed and imbedded." Gotta. Varieties in Composition. a. Sanidine Trachyte. An aggregate of sanidine crystals, with some amphibole or mica. From coarse to fine, and from porphyritic to compact. b. Drachenfels Trachyte. Containing oligoclase in addition to the sanidine, with some mag- nesia-mica, and amphibole, also pyroxene, magnetite, and titanite. c. Domyte, or Domite (after Puy de Dome, Au- vergne). Oligoclase trachyte, having no sanidine. It also contains some amphibole or pyroxene, and dark-coloured mica. d. Andesyte, or Andesite (after the Andes). Fine INGENITE or compact dark colour, with imbei e. Trachydoleryte, or Trachydo "A. compound of oligoclase (or labradorite) with amphibole or 'pyroxene, some mag- netite^ and frequently also mica. These minerals lie imbedded in a grey or brown matrix/' Gotta. Trachydoleryte is the passage-rock between the Trachytes and Augytes. Varieties in Texture. f. Granular Trachyte ; g. Compact; h. Porphyry ; . i. Trachyte-lava or Vesicular Trachyte; and j. Alum-stone. The last does not appear to be a normal rock, but to be due to decomposition. J. Augitic Group. Aggregates of felspar with pyroxene and ampbibole ; they frequently contain mica and magnetite, while quartz is rarely present. The Augitic group includes all the basic volcanic rocks ; they may be compact, crystalline, granular, porphyritic, amygdaloidal, vesicular, or variolitic. A. AUGYTE Or AUGITE, DoLEftYTE Or DOLERITE, BASALT. A crystalline granular aggregate of labradorite or nepheline and pyroxene, with some titaniferous magnetite; usually blackish or dark-coloured. In the compact mass there often occur pi ominently distinct grains or even crystals of olivine, labradorite, pyroxene, and magnetite. NOTE. The name Basalt is given above, as it is in such common use ; it ought, however, to be solely confined to the compact varieties. jSee Dolerjte among the Plutonic rocks. 74 HANDY-BOOK OF ROCK NAMES. Varieties in Composition. a. Neplielite Augyte, when this mineral is the felspar. ~b. HauynopJiyre (Rammelsberg) ; hauyne being in the place of labradorite. c. Allogovyte, or Allogovite (Winkler), a reddish variety of labradoritic augyte; and d. Common Augyte, Labradoritic Augyte. Varieties in Texture. e. Anamesyte, or Anamesite (Leonhard). f. ffasalt, or Compact Augyte. e and/ seem to be different names for the same kind of rock, as both refer to those angytes that are so fine-grained and compact that the consti- tuents are undistinguishable. y. Porphyritic, containing felspar crystals. li. Amygdaloidal, having almond-shaped concre- tions. i. Basalt Lava, or Vesicular Augyte, being scori- aceous or full of minute holes ; and j. Variohtic, when there are dark grains in a lighter-coloured mass. li and i always merge one into the other, as the latter was the original condition of all amygda- loids. jB. LEUCITYTE, or LEUCITITE, LEUCITE-EOCK. A more or less distinct aggregate of leucite and pyroxene, with some magnetite. Varieties are, a. Compact; b. Leucitophyre, or PorpJiyritiCy having felspar crystals; c. Amyg- daloidal ; and d. Leucityte Lava, or Scorious or Vesicular Leucityte. INGENITE KOCKS. 75 K. Volcanic Tufa and Peperino (Ingenite in part, Derivate in part). According to Scrope, the Italian geologists restrict the term tufa to the felspathic or trachyte aggregates, which are grey or whitish ; while the name peperino denotes the augitic vari- eties, which usually are brownish. A. TUFA. A trachytic aggregate of slag, ash, pieces of pumice and lava, with fragments of various other rocks. It may be arenaceous, argillaceous, conglomeritic, or brecciated. The principal fragments and particles are of trachyte. Varieties are, a. Trachyte Tufa ; b. Pumiceous Tufa or Pumiceous Sand, which have re- ceived the following local names : Trass (Uhine), Tosca (Sicily), and Pausilippo Tufa (Teneriffe) ; c. Phonolyte ; and d. Pozzuo- lana, a volcanic sand, very useful in the construction of mortar for hydraulic works. B. PEPEEINO. A light porous rock ; augitic sand, scoria, cinders, &c., cemented together, the grains having a peppercorn-like appearance. Varieties are, a. Augyte Peperino ; b. Leucityte ; and c. Palagonyte, called after Palagonia, in Sicily. C. VOLCANIC CoNGLOMEEATE,with its varieties, a. Vol- canic Breccia, and b. Volcanic Agglomerate. Some of the mechanical accompaniments of the volcanic rocks consist of more or less stratified accumulations of blocks and frag- ments of volcanic and other rocks, usually more or less loose, but sometimes cemented together. If the contained blocks are round or roundish, the rock may be called Volcanic F 76 HANDY-BOOK OF ROCK NAMES. Conglomerate; if they are more or less angular, a Volcanic Breccia ; while if the accu- mulation is massive and without stratification, LyelPs name of Volcanic Agglomerate may be adopted. Class IV. TRANSITION OR METAMOEPHIC SEDIMENTARY ROCKS. THESE rocks, similarly to the metamorphosed igne- ous rocks, may occur in various degrees of change, from a rock scarcely altered to a rock undistin- guishable from granite, in accordance with the in- tensity of the metamorphic action to which they were subjected. The lowest degree of metamorphism seems to be, principally, induration, with the planes of the most conspicuous structure (whether lamination, clea- vage, or jointing) glazed or micacized, while, at the same time, peculiar structures are developed. In finely laminated, or cleaved rocks, a crumpling takes place ; in others a nodular or concretionary development ; in some the joint-lines and the rock in their immediate vicinity, are silicified or hard- ened, so that on the weathered surfaces of the rocks are formed well-marked rectangular, rhombic, or oblique depressions. In the second degree, the rocks become typical schist; in the third gneiss; while in the fourth they become granitoid, and from that pass into typical granite. Rocks usually pass in this order to the highest degree of change; however there are exceptions, as some rocks are more susceptible of change than others, on account of their mineral constituents. INGENTTE EOCKS. 77 Thus some sandstones, or even shales that contain the constituents of gneiss, may have a gneissoid aspect, while the associated rocks have only been changed into schist. NOTE. The following changes in sedimentary rocks were observed in co. Mayo, Ireland : Felspathic and micaceous sandstones, changing into mica-schist and gneiss. This gneiss, however, was not typical ; that is, the quartz, mica, and felspar were not arranged in leaves ; nevertheless the rocks contained these three ingredients, and had an incipient foliation ; quartzose sandstones and grits, changing through quartz- schist, or quartz- itic mica-schist into gneiss ; green tuffose shale and slate, through hornblende schist, chlorite schist, or talc schist into basic gneiss ; argillaceous shale and slate, through argillyte into mica-schist or chloritic mica-schist, and from that into gneiss ; felstone or felsitic tuff, through felsitic schist into steatitic schist, garnetiferous schist, or talcose schist. L. Gneiss. When typical, a crystalline granular aggregate of quartz, felspar, and mica; occurring in leaves or plates, more or less parallel to one another. Typical gneiss is rather uncommon, as usually various other minerals besides the quartz, felspar, and mica occur, disarranging the regularity of the leaves. Varieties in Composition. A. FELSPATHIC and FELSITIC GNEISS, having one or more felspars as the predominant ingredients. These may be divided into, a. Orthoclase, b. Oli- goclase, c. Alpinyte (Simler), and d. Adularia- s. Gotta. c. is named after the Alps. It is principally made up of a variety of oligoclase, and is a gneis- soid aggregate of quartz, oligoclase, and an un- determined flaky green mineral. The latter Gotta suggests (e probably belonging to the mica species." 2 78 HANDY-BOOK OP EOCK NAMES. A variety of felspathic gneiss, having adularia in the place of orthoclase, is mentioned by Cotta. Felspathic gneiss is the passage-rock between gneiss and felsyte schist. B. MICACEOUS GNEISS, containing much mica. Its varieties are, a. Two-mica Gneiss, b. White Mica Gneiss, c. Slack Mica Gneiss. Varieties might also be named after the different kinds of mica. Micaceous gneiss is the passage-rock between gneiss and mica-schist. G. QUARTZITIC GNEISS. This is the passage-rock between gneiss and quartz- schist, or quartzyte. D. BASIC GNEISS has numerous varieties, according to the most prevailing accessory, or the mineral that gives character to the rock mass. The most particular are, a. Hornblendic or Amphi- bolic; b. Chloritic or Bipidolitic ; c. Talcose, and d. Protogene Gneiss, when talc replaces the whole of the mica. NOTE. It is said by King (India), that to a gneissoid rock, composed of quartz, felspar, and talc, the name Protogene was first given, and not to an intrusive rock. Hornblendic gneiss is sometimes erroneously and unscientifically called syenitic gneiss, while chloritic gneiss and talcose gneiss have absurdly by some been classed together under the name of Protogene gneiss. (See note on the, Hornblendic Granite, page 33.) E. IOLITIC GNEISS, F. HEMATITIC GNEISS, and G. GRAPHITIC GNEISS, may be thus named respec- tively, if iolite, micaceous iron-ore, or graphite replace most of, or the whole of the mica. Structural Varieties. H. COMMON or GREY GNEISS may be divided into, a. Compact Gneiss, b. Slate-gneiss, c. Ribaned INGENITE KOCKS. 79 or Lagen Gneiss, and d. Fibrous or Stangel Gneiss. Compact gneiss is usually a more or less indu- rated grit, or in some cases it may be a slightly altered bedded felstone. In Slate gneiss there is a distinct slaty cleavage in a fissile mass of small even-grained particles, the mica being seen on the cleavage-planes alone. Eibaned gneiss is when the constituents occur in thin layers, and form a riban ; while in Fibrous, or Stangel gneiss, the ingre- dients are placed "in a fibrous manner towards one direction ; so that a peculiar linear parallel conformation is produced." In a variety of fibrous gneiss the quartz particles are of an elongated almond-shape, and a cross section of the rock has a peculiar aspect. I. OBLIQUE GNEISS, having as varieties, a. Curled Gneiss, b. Nodular Gneiss, and c. Conglomeritic Gneiss. The straight linear arrangement of the leaves of the constituents may be deflected by various causes; in some by oblique lamination, or by cleavage in the original rock ; in others by a crumpled foliation, or spheroidal structure ; also by the original lamination curling round contained nodules or blocks, if the rock before alteration was nodular or conglomeritic. In ordinary gneiss, the direction of the foliation seems to be due to structure in the original rock; while in granitoid gneiss, it nearly always is linear, parallel, and regular, apparently being a more or less introduced structure. Conglomeritic, and some nodular rocks, appear capable of resisting this new arrangement longest, for in many rocks of these kinds, even when very granitoid, the foliation will 80 HANDY-BOOK OF ROCK NAMES. remain deflected or curled in the immediate vicinity of inclosed blocks or nodules ; while in some gra- nites regular or irregular masses, differently con- stituted to the rest of the rock, will occur. In West Galway, Ireland, conglomeritic gneiss is usually associated with metamorphosed igneous rocks, and probably is metamorphosed conglo- meritic tuff, or agglomerate. J. PORPHYRITIC GNEISS ; K. GRANITOID GNEISS. These subgroups are allied, nearly all por- phyritic gneiss being also granitoid. Gneiss may have large and prominent crystals of felspar disseminated through the mass. This usually occurs in the granitoid subgroup, but not always. In some granitoid gneiss there is a dis- tinct foliation, while in others it is indistinct. The degree of distinctness of the foliation of the granitoid gneiss appears due to the intensity of the metamorphic action to which it was exposed. Granitoid gneiss is the passage-rock between gneiss and granite.* M. Schist [Gr. scliistos, split or divided]. A crystalline fissile aggregate, consisting, when typical, of two well-developed minerals, occurring in thin plates or leaves. Mica is usually one of these minerals; however, various others also occur, sometimes as accessories, but locally as essen- tials, thereby forming different subgroups and vari- * Hereafter microscopists may prove that granitoid gneiss ought more properly to be classed with the Granitic rocks (Class No. 1), and taken out from the Transition rocks (Class No. 4), as in it the original structure is obliterated, except in a few rare exceptions. The mineral constituents seem to be altogether crystalline, no felsitic or felspathic tuff occurring in granitoid gneiss. INGENITE ROCKS. 81 eties. When mica is absent, quartz is nearly always present. Schist is easily separated along its foliation- planes, while across them it is tough, and breaks with from an uneven to a hackly fracture. A. ARGJLLYTE, or ARGILLITE, Argillous or Clay Schist. A fissile more or less indurated argillous rock, having the planes of the most con- spicuous structure in the original rock, glazed, mineralized, or micacized. Certain minerals, as chiastolite, phyllite, pyrite and such like, are developed in some, and peculiar structures in others ; thus forming varieties. Varieties in Composition. a. Chiastolitic Schist. b. Phyllitic Schist, or Ottrelitic Schist. c. Carbonaceous Schist. d. Alum-schist. e. Spilyte or Spilite, or Calcareous Schist, and f. Dolomitic Schist. Chiastolitic schists are mostly argillous rocks ; nevertheless some are micaceous. The crystals are usually disseminated through the mass quite irre- gularly, but in some varieties they are stellated, usually on the surfaces of the original structure of the rock. Phyllitic schist contains laminae of phyllite (Ottrelite). Carbonaceous schist is rich in carbon, and often is pyritous; of it Alum- schist seems to be a variety, being due to the decomposi- tion of pyrite in pyrito-carbonaceous schist. Spilyte and Dolomitic schist are passage-rocks into schistose limestone and schistose dolornyte. 82 HANDY-BOOK OF EOCK NAMES. Structural Varieties. g. Folded or frilled Argillyte, h. Contorted, and i. Fibrous. Variety g has a folding or crumpling that gives it a frilled aspect : this peculiar folding is only found in some of the schists, and evidently is solely due to the metamorphic action, as it does not follow any structure in the original rocks. In variety i the particles are so linear and parallel- arranged as to give the rock a woody aspect, a weathered block looking like the butt of a sallow or some such tree. Argillite is the passage-rock between normal clay-slate, or shale, and mica-schist. It occurs in various stages of metamorphism. Sometimes the whole mass appears homogeneous, differing only from clay-slate, or shale, by its superior lustre; nevertheless it is rarely without traits, more or less characteristic, of mica-schist; such as the crump- ling, crushing, folding, twisting or contortion of the laminso; also the hardening of the joint and other lines, with the development of minerals, especially on the surfaces of beds or on the lamina- tion and cleavage-planes. B. QUAETZYTE, or QuAETZiTE, Quartz-schist. Chiefly consists of quartz with some mica; the latter being most conspicuous on the planes of foliation. Varieties in Composition. a. Itacohimyte (Eschwege), Pedra elastica (Anchi- eta), Micaceous Quartzyte. " A fine-grained and at the same time schistose compound of . INGENITE ROCKS. 83 quartz with some mica, talc, or chlorite." Gotta. Kenwood says of the Itacolumyte of Minas Gerais, " quartzose talco-micaceous slate." These flexible quartzytes were first noted among the metamorphic sedimentary rocks of Brazil, and were named after Itacolumi Peak. Burton says there are three different kinds of rock named after this peak : 1st, the flexible quartzyte, or Pedra elastica, under which name it was described nearly three centuries ago by Padre Anchieta ; 2nd, Dia- mantine itacolumyte, the matrix of the diamond, " a hard talcose rock of distinctly laminated quartz, white, red, or yellow, granular, with finely-dissemi- nated points of mica;" and 3rd, in Minas the name is applied to " refractory sandstone grits, a fine crystalline rock evidently affected by intense heat." The peak itself consists of none of the three kinds, although all are called after it. Jukes thus describes Itacolumyte : " A genuine unaltered sandstone, more or less micaceous, like other sandstones, but the mica in worn spangles, not in connected flakes." The rock, of which this is a description, came from India. In it are lines that appear due to deposition ; when placed under the microscope, it is found to be full of long drusy cavities, which lie in lines rudely parallel with the structure of the rock. The cavities open and shut when the slab is bent. According to Dana, Itacolu- myte pertains to the talcose series, and is the matrix of the diamond ; this evidently is Burton's second kind of rock. b. Itabiryte (Bschwege), Jacotinga. Ferruginous quartz-schist, a variety of Itacolumyte, named after Itabira, in Brazil. Eschwege, 84 HANDY-BOOK OF ROCK NAMES. who first described the rock, makes it the matrix of the diamond. Some very ferri- ferous varieties are said to be worked in Brazil as iron-ores ; they are more or less auriferous. Itabiryte, Dana says, " contains much specular iron-ore in grains or scales, or in the micaceous form." Jacotinga Hen- wood describes as an " auriferous mica- ceous iron-schist." c. Felsitic Quartzyte An aggregate of quartz and felsite, sometimes also felspar and a little mica ; usually more or less massive, rarely well foliated. Structural Varieties. d. Quartz Rock (Jukes), Granular Quartzyte. e. Fibrous Quartzyte, and /. Conglomeritic Quartzyte. Variety d is fine-grained, homogeneous, and more or less saccharoid in aspect, often merging into felsitic quartzyte (c). e. has an arrangement in long rude prisms like coarse wood; while /. contains pebbles, usually ovate, but sometimes more or less angular; this is evidently a meta- morphosed conglomerate, the normal form of the pebbles having been elongated by the subsequent metamorphic action. Quartzyte or Quarfcz-schist (B) is an undoubted metamorphic sedimentary rock, originally a highly siliceous sandstone or grit. There are, however rocks described as Quartzyte or Quartz-rock that seem not to be metamorphic rocks, but rather normal rocks, either deposited from a solution, or perhaps a variety of intrusive rock. Some of these INGENITE ROCKS. 85 quartz-rocks appear to occur as masses in unaltered rocks. Felsitic quartzyte is a remarkable variety; some would seem to be metamorphosed Petrosilex ; while others merge into quartz-rock on the one hand, and into Felsitic granite or Felsite-rock on the other. Some also occur in bedded masses, when they may possibly be metamorphosed felspathic sandstones. C. FELSYTE SCHIST. A felsitic fissile rock ; colour whitish, greyish, or greenish; from compact to mealy or granular in texture. NOTE. Some of the compact varieties of Felsyte schist are identical with rocks named by Krantz as Leptinyte or White- stone ; on the other hand, Cotta classes Leptinyte, with Granu- lyte, apparently considering both as intrusive rocks. Varieties in Composition. a. Micaceous, b. Quartzose, and c. Pyritous. Varieties in Structure. d. Ribaned, when the mineral constituents are in layers or seams, alternating with one another. e. Mealy, having a leafy or scaly structure ; and /. Gneissoid or granular, a granular felsitic rock, slightly fissile, with grains of quartz dissemi- nated through the mass, also a little mica. NOTE. Gneissoid or granular felsyte schist merges into fel- sitic quartzyte. In some localities it is an undoubted bedded or interstratified rock, while in others it is evidently intrusive. Perhaps in the first case it may be a metamorphosed stratified felstone or tuff (which could only be determined by a micro- scopical examination), while in the latter it may be a metamor- phosed intrusive felstone. The latter variety of granular felsyte schist appears to answer the description of the rock called granulyte by Cotta. 86 . . HANDY-BOOK OF ROCK NAMES. D. MiCA-scm-s^^When typical, a foliated or fis- sile aggregate of quartz and mica. Usually the foliation is regular; nevertheless it may be crumpled, crushed, folded, twisted, con- torted, curled, nodular, or spheroidal. Varieties in Composition. a. Two-mica Schist, b. Chloritic, c. Talcose, d. Garnetiferous, e. Chiastolitic, f. Andalu- sitic, g. Amphibolic, h. Epidotic, i. Quartzose, j. Felsitic, k. Calcareous, I. Schorlaceous, m. Pyritous, n. Pyrrhotitic, o. Hematitic, and p. Graphitic. The varieties in composition are named after con- spicuous minerals, locally essentials. Most of these rocks, however, are only passage-rocks into the other subgroups of schist ; some even (such as Epidotic mica-schist) are not normal rocks, but due to a secondary change in the mineral constituents. Structural Varieties. q. Fine Mica-schist, where all the ingredients are small and even- grained. r. Ribaned, with the minerals in layers or bands. s. Fibrous, with a woodlike arrangement. t. Nummoid, having in it small discs of quartz, giving the rock an appearance as if studded over with pieces of small coin. u. Wavy. v. Frilled, having the foliation folded or crum- pled on itself. w. Curled or Spheroidal. x. Knotty or Concretionary. y. Nodular ; and z. Gneissoid; the last-named variety being the pas- sage-rock between mica-schist and gneiss. INGENITE ROC #. BASIC SCHISTS. Schist amphibole, ripidolite, talc, and tEeHSS/replace the whole, or nearly the whole, of the mica, and become essentials of the rock. Varieties are, a. Hornblende, OT Amphibole Schist ; b. Actinolite Schist ; c. Chlorite or Ripidolite Schist; d. Chloritoid Schist (Hunt) ; e. Pot- stone; f. Talc Schist; g. Garnet Schist; h. Tourmaline, or Schorl Schist; and i. Rhceti- zitic or Magnesia Schist. It is evident that with more mica, any of these rocks may pass into one of the varieties of mica- schist ; or that one of the varieties of mica-schist, by a loss of its mica, may pass into one of the basic schists. Sterry Hunt describes a dark-coloured Canadian subvariety of chlorite- schist as largely composed of chloritoid, a mineral allied to ripidolite and phyllite; and Gotta describes potstone as a felt-like web of ripidolite, and rarely foliated. Per- haps these two varieties of schist would be more properly classed as varieties of argillyte. B/heeti- zitic schist is described by Forbes as remarkable for the predominance of silicates of alumina and magnesia, rhaetizite, iolite, chiastolite, &c. The basic schists have numerous structural varie- ties. They are, however, very similar to those mentioned when describing mica-schist ; therefore it is unnecessary to enumerate them here. F. METALLIC SCHISTS. r Schists, in which a mineral ore replaces part or the whole of the mica, and gives a character to the rock mass. The principal varieties are, a. Mico-iron Schist, b. Pyrite Schist, and c. Pyrrhotite Schist: other ores may also give a character to a rock. 00 HANDY-BOOK OF ROCK NAMES. G. BURNT SHALE. Altered argillous rocks, due to the burning of carbonaceous beds. Varieties are, a. Burnt Clay, b. Rock Slag, and c. Porcelanyte. H. MINERALS FORMING BOCKS. a. Quartz and Jasper, generally in veins. b. Corundum, in subordinate layers. c. Apatite, sometimes forms compact spheroidal masses. d. Magnesite, in subordinate masses. e. Orthoclase. f. Pistacite ; and g. Pycnite, generally in veins. h. Lepidolite, rarely forms independent rocks. i. Lievrite or ILvaite, in subordinate beds. j. Magnetite. k. Anthracite. I. Graphite. Normal graphite is pure carbon with a little oxide of iron mechanically mixed. Graphite occurs jn beds and imbedded masses, laminae, or scales, in granite, gneiss, schist, and schistose limestone. Of it Dana says, "It is, in some places, a result of the alteration by heat of the coals of the coal form- ation." m. Eisenkiesel, "a, concretionary rock, made up of red and brown iron-ore, and fragments of bright red jasper." Bouerman. n. Garnet Hock. One variety is massive, of a milk-white colour, very hard and heavy, with a peculiar graining through the mass. Others are brownish or reddish, and more or less cry stalline ; these usually pass into INGENITE EOCKS. 89 a highly crystalline vuggy rock, that has as acces- sories, pyrite, marcasite, chalcopyrite, epidote, cal- cite, &c. : occurs in veins and subordinate masses. N. Slate [according to Worcester, originally spelt " Sclate." Old Fr. esclat, a splinter, a shingle. Celtic scorlt, to split or cleave] . Originally shale or clay, into which a subsequent slaty cleavage has been introduced. Some slates are said to belong to the Metamor- phic series. The slaty structure, however, seems more connected with Sedimentary than with Inge- nite rocks. Slates often occur associated with unmetamorphosed sedimentary rocks, and many metamorphic rocks are known to have been cleaved prior to their being metamorphosed. Slates are mentioned here, but they will be described here- after among the Derivate rocks, as varieties of the subgroup Argillous rocks (see page 103). 0. Calcareous Rocks (Lat. calx, calcis, lime). A. SCHISTOSE LIMESTONE. A crystalline granular or nearly compact aggregate of calcite, with more or less ripidolite, mica, felsite, quartz, pyrite, galenite, &c. ; often more or less fissile, some- times highly schistose; usually the foreign minerals are in more or less regular lines or layers, but in some varieties they are dis- seminated through the mass of the calcite. a. Cipollino, or Micaceous Limestone. Eich in mica, which gives the rock a schistose tex- ture ; this variety graduates into Spily te. b. Calciphyre(Broiigma,rt), or Garnetiferous Lime- stone, containing garnets and pyroxene or felspar. 90 HANDY- BOOK OF ROCK NAMES. c. Hemitrene, or Amphibolic Limestone. In addi- tion to the amphibole, it generally contains graramatite. d. Felsitic Limestone. The felsite often occurs in highly crumpled parallel layers. e. Statuary Marble, or Saccharoid Limestone. "A white, fine-grained rock, resembling loaf sugar in colour and texture, working freely in any direction, not liable to splinter, slightly translucent, and capable of taking a polish. Flakes of mica or chlorite some- times exist in it/' Jukes. Typical statuary marble should answer the above description, but the rock in mass is often more or less schistose, and also streaked with dark lines, caused by foreign minerals being associated with the calcite. /. Granular Schistose Limestone. A granular crystalline, more or less schistose limestone ; containing some mica, ripidolite, felsite, or even quartz. Colour white, pale grey, dove, light blue, greenish, reddish, purplish, or yellowish. It is often impregnated with microscopic crystals of pyrite, marcasite, galenite, or chalcopyrite. P. Pseudomorph. Calcareous Rocks. Most of these rocks are pseudomorph metamorphic rocks ; some, however, may be derived direct from the original rocks. A. SCHISTOSE DOLOMYTE. A crystalline aggregate of calcite and dolomite, together with some ripidolite, talc, or mica : pyrite, marcasite, or chalcopyrite are usually present in greater or less quantities, but minutely disseminated INGENITE BOOKS. 91 through the mass. The rock, though usually schistose, may be sometimes compact or granular ; when compact, it breaks with a conchoidal fracture. The colours of these dolo- mytes are very various : a handsome variety is milk-white. Many of them weather into a micaceous ferriferous sand. Some varieties are, a. Micaceous ; b. Pyritous; c. Saccharoid ; and d. Granular. The most marked varieties in composition are those due to an excess of mica, or one of the pyrites ; and in structure, the saccharoid and the granular. The latter are somewhat similar in aspect to saccharoid and granular limestone, but harder, although more easily decomposed by me- teoric action. Ophyte and steatyte occur associated with the calcareous rocks, but more especially with dolo- myte, they being due to pseudomorphic action. At Lissoughter, Galway, Ireland, blocks of dark green very pure serpentine, coated with a thick crust of rusty yellow impure meerschaum (locally called Cream), are found on or close to the surface of the ground ; lower down, the solid rock was an ophicalcyte, often micaceous or felsjtic ; while in depth the ophicalcyte passed into a more or less schistose dolomyte. Dana, Jukes, and others also mention dolomytes which have been noted as gra- duating into ophytes. It should be borne in mind, that the ophytes and steatytes now to be described are pseudomorph sedimentary rocks, while those previously mentioned (see page 63) were pseudo- morph igneous rocks. B. OPHYTE [Gr. ophis, a serpent], Serpentine, Verd antique, Ophiolyte (Dana and Hunt). When 92 HANDY-BOOK OF ROCK NAMES. pure, a compact, dark green aggregate of ser- pentine, usually associated with calcite, dolo- mite, and magnesite ; and with such minerals as talc, ripidolite, magnesian mica, &c. ; unctuous to the touch on fresh fractures. The most common varieties are, a.Ophidolomyte; b. Ophimagnesyte ; c. Ophicalcyte ; and d. Ophyte Schist. The ophytes have been classed by Hunt: 1st, Dolomitic, 2nd, Magnesitic, or 3rd, Calcitic, ac- cording to whichever mineral gives a character to the rock-mass. To these may be added the schis- tose varieties, as all ophytes of this class become in places schistose, they being impregnated with, or having layers of, mica or some other conspicuous ingredient not necessary to a typical ophyte, but giving a more or less marked schistose character to the rock-mass. 0. STEATYTE, or STEATITE [Gr. stear, steatos, fat] . A grey, blue, green, reddish or whitish fissile aggregate of steatite, with some talc, ripidolite, amphibole, or magnesian mica : has a mealy aspect ; very unctuous to the touch ; cuts easily, but tough. The principal varieties are, a. Felsitic; b.Horn- blendic ; c. Pyroxenic ; d. Micaceous; e. Steatyte Schist (this class of steatyte always graduates into a schistose rock);/. Pyrallolyte (Nordenskiold), greyish to clouded milk white in colour, compact, translucent, stea- titic rock. According to Hunt, it is identical in composition with talc. Pyrallolyte occurs associated with ophyte, but seems to be only a secondary rock filling up INGENITE BOOKS. 93 . GYPSUM [Gr. ge, earth; epso, I boil] . A hydrated sulphate of lime ; usually crystalline, but some- times compact or fibrous ; soft ; generally white or whitish. a. Alabaster [after Alabastron, a town in Egypt] . b. Granular Gypsum, always almost white, some- what translucent; granular and finely crys- talline ; sometimes it is fissile, each bed being composed of many layers of little crystals, slightly differing in colour and texture. c. Compact gypsum, rare. d. Fibrous, or having a wood-like structure. n 108 HANJ)Y-BOOK OP EOCK NAMES. e. Selenyte, Spathic or Sparry gypsum, trans- parent varieties. /. Tripestone, "a variety both of texture and composition. It is formed of thin layers of pure white gypsum, alternating with grey argillaceous gypsum, the whole twisted or crumpled to resemble a ruff/' Gotta. Gypsum merges into impure, more or less mechanically formed varieties. C. ANHYDRYTE, or ANHYDRITE. "A. granular or compact aggregate of anhydrous sulphate of lime ; harder than gypsum ; white, grey, or blue." Gotta. The varieties of anhydryte are very analogous to those of gypsum, the more marked being a. Granular, b. Compact, and c. Fibrous. D. DOLOMYTE, or DOLOMITE [after M. Dolomieu] . A granular crystalline aggregate of dolomite associated with some calcite ; more or less saccharoid ; does not effervesce, or only slightly with dilute acid. Dolomyte weathers into a ferruginous sand, Dolomitic sand. NOTE. Some dolomytes are of purely chemical origin, while most dolomytes are partly chemically and partly mechanically, or even perhaps organically, formed. Only the first belongs to this group (B), the others are described in group (C), page 120. E. QUARTZ. Pure or nearly pure silica. Varieties of Quartz are a. Chert [Celtic cairt or chairt, rough bark ; as chert forms a rough bark or coat to the beds of limestone], b. Flint, c. Menilyte, or Menilite. Hard, com- pact, containing more or less carbonaceous matter ; breaks with from a conchoidal to a semiconchoidal fracture ; colour white, grey, yellowish, brown, black, and sometimes blue. DEEIVATE KOCKS. 109 Flinty and Menilyte occur in layers of nodules, thin beds, and concretions ; sometimes, however, as is especially the case with chert, they form massive strata. Menilyte is found in the Tertiary limestone. Flint is characteristic of some chalk, while chert is mostly found in the Carboni- ferous and older limestone, and in some shales. Jukes writes of these rocks, " Almost all large masses of limestone have their flints or siliceous concretions. Pure siliceous concretions occur even in the fresh- water limestones and gypsum beds of Montmartre." d. Jasper and e. Agate (particoloured varieties). /. Basa wjte, or Basanite, Touchstone, or Lapis Lydius (Pliny), a, velvet-black cherty variety, used on account of its hardness and black colour for trying the purity of the precious metals. F. LIMONITE EOCK. A fissile, porous, compact or fibrous, earthy or arenaceous hydrated oxide of iron, bedded or in veins ; reddish, yellowish, or blackish in colour. Varieties are a. Limonitic Shale ; b. Oolitic Brown Ore; c. Reniform Iron Ore; d. Pea-iron Ore; e. Bog-iron Ore : the latter having sub- varieties, (a.) Black Bog-iron Ore; (b.) Yellow Bog-iron Ore, or Yellow Ochre; and (c.) Sparry Bog-iron Ore. Limonite Rock sometimes occurs interstratified among rocks of Secondary age,* but other vari- * In co. Clare, Ireland, it occurs in beds among Cambro- silurian rocks, while in Limerick and Queen's counties it has been found associated with black shales near the junction of the Carboniferous limestone and the lower shales of the Coal- measures. In Ulster it occurs interbedded with Whinstone of Tertiary age. H 2 110 HANDY-BOOK OF EOCK NAMES. eties, such as c, d, and e, usually occur associated with surface accumulations, such as drift or peat. Cotta writes of Oolitic Brown Ore, that it " occurs in the form of layers in many formations." Bog- iron Ore, and its sub-varieties, are due to the decom- position of iron ores (often pyrite or marcasite), or minerals, or rocks containing a large percentage of iron. Black Bog-iron Ore in general is rich in manganese, while the yellow and sparry subvarieties are respectively argillaceous and siliceous. 6r. HEMATITE ROCK. A granular or compact aggre- gate of hematite, with arenaceous or argillaceous matter ; usually reddish in colour, but some- times blackish or rich brown. Varieties are a. Red-iron Mould, or Red Ochre ; b. Reddle or Raddle; c. Sparry Red-iron stone ; d. Specular Iron. Of these varieties, the principal are a, b, and c, while d seems to be rather rarely a rock-mass. e. Topanhoacanga, or Moorshead Rode. This Brazil variety is found among the surface deposits, and consists of fragments of specular iron, micaceous iron, and magnetite in a ferruginous matrix. In this rock there are various accessories; even, on rare occa- sions, grains of native gold. II. SPHEEOSIDEEYTE, or SPHEROSIDEEITE, Clay-iron Stone. A crystalline aggregate of siderite combined with argillaceous and carbonaceous matter. Impure varieties are arenaceous. Splierosideryte, or Clay -iron Stone, occurs in thin beds, layers, and nodules, in beds of clay, clunch, and shale. It is typical of the coal-measures, but DERIVATE EOCKS. Ill is also found associated with, other rocks. An im- portant Coal-measure variety, very rich, in carbon- aceous matter, is said by Bristow to be called Black-band. Some beds of the latter are so rich in carbon, that they can be burned by themselves, and might be classed among the coals. I. MINERALS OCCURRING AS EOCKS. Some minerals occur in subordinate masses interstratified with the sedimentary rocks ; these, however, are not of very frequent occurrence, minerals in mass more often being found in veins, nodules, or irregular accumulations. a. Asphalts [Gr. asphaltos], Bitumen, Mineral Pitch. Colour brownish, blackish, or black; lustre like that of black pitch, odour bitu- minous, melts at from 90 to 100, and burns with a bright flame. Of this rock Dana writes : " Asphaltum belongs to rocks of no particular age ; the most abundant deposits are superficial." b. Pyrite occurs in thin beds, layers, and as nodules. c. Cinnabar. " Occurs in beds in slate-rock and shale, and rarely in granite or porphyry/ 1 Dana. This observer also' states that this mineral occurs as rock-masses, both in unaltered and metamorphosed sedimentary rocks. d. Boracite " occurs in beds of anhydryte, gyp- sum, and. salt." Dana. e. Trona, "in North Africa, forming a rock which is even used for building purposes." Gotta. f. Aragonite, with its subvariety Flosferri. "The 112 HANDY-BOOK OF EOCK NAMES. most common repositories of aragonite are beds of gypsum, and beds of iron ore (where it occurs in coralloidal forms, and is de- nominated Flosferri), basalt, and igneous rocks. " Dana. g. Manganese Ores, generally in the older rocks, but also in surface deposits. h. Rhodochrosite occurs generally in veins, but at Glendree, Clare, Ireland, it forms part of the surface-deposits. i. Bole, in subordinate masses, in limestone. j. Opal, or Vitryte, in very subordinate masses. k. Fluorite, and I. Barite, rarely found in beds or layers, often occur as gangue in mineral veins. m. Anlcerite, sometimes as an independent rock. n. MalacJiite, usually in veins. o. Melanite, in small accumulations. p. Galmey, or Oatamine, as aggregates in dolo- myte. q. Zincite, r. Galenite, s. Stibnite, and t. Arseno- pyrite, rarely occur as subordinate layers, but more generally in veins. it. Sulphur, in concretions and layers, princi- pally in marl and limestone, also in the vicinity of volcanoes. v. Wavellite, in subordinate beds or layers. w. Chalcopyrite, usually in veins. C. Eocks partly mechanically, partly chemically, and partly organically formed. These rocks are always more or less crystalline, and usually occur as subordinate beds, interstratified with sedimentary rocks, but not always. A. LAMINATED or STRATIFIED COAL. A more or less fissile crystalline aggregate of carbonaceous DERIVATE ROCKS. 113 matter ; arenaceous or argillaceous to a greater or less degree. Most coals do not belong to the Subaqueous rocks ; some, however, have been formed mecha- nically from carbonaceous matter, that was first denuded, and afterwards deposited in the sea, or other waters. NOTE. At the present day the accumulation of mechanically- formed coal can be observed. Wherever peat-bogs or even hard coal-beds are exposed to denudation, more especially to marine abrasion, they are gradually carried away to be deposited in seas, lakes, &c., forming stratified more or less arenaceous or argillaceous carbonaceous beds, which eventually must be in- durated, forming a hard coal. Some of these deposits in the vicinity of the Irish coast are of considerable thickness. Varieties are a. Gannel Coal, a compact, semi- fissile coal ; breaks with a semiconchoidal smooth fracture, with little or no lustre ; colour dull black or greyish black. Cannel Coal is bituminous and often caking. Of it Dana writes : (C On distillation it affords, after drying, 40 to 66 of volatile matter, and the material volatilized includes a large proportion of burning and lubricating oils. It graduates into oil-producing coaly shales, the more compact of which it much resembles." NOTE. Some varieties of anthracyte have erroneously been classed as Cannel coal, on account of their smooth, close texture. Subvarieties are (a.) Parrot Coal, (b.) Horn Coal. A Scotch subvariety is called Parrot Coal, because it burns with a crackling noise ; while a Welsh is named Horn Coal, as it emits, when burning, an odour like that of burnt horn. An earthy subvariety is called, in Yorkshire, Clod. 114 HANDY-BOG^ OF EOCK NAMES. And (c.) Torbanyte, Boghead Cannel, Boghead Mineral (after Torbane Hill, Scotland). A dark brown variety of cannel coal ; yellowish streak, without lustre, and having a sub- conchoidal fracture. Torbanyte yields over 60 per cent, of volatile matter, and is used for the production of burning and lubricating oils, paraffin, and illuminating gas. b. Splint Coaly Splent Goal. A hard, laminated, bituminous coal ; not easily broken or kin- dled, though, when lighted, it affords a clear, lasting fire. According to Page, the name " Splint " or " Splent," is derived from the coal splitting (or splenting) up " in large flaggy or board-like laminae." c. Culm, a fissile, flaggy, shaly, flaky, or scaly variety of non-bituminous coal or Anthracyte. Culm sometimes occurs in independent beds, but more often it is found associated with Anthracyte. The flaky or scaly nature of some culm may possibly be due to the growth and decay of organic matter in layers, but in others undoubtedly it is due to carbonaceous matter having been deposited in water. d. Bituminous Shale, and e. Carbonaceous Shale. Respectively bituminous or non-bitumi- nous shaly aggregates of coal, clay, sand, and such-like ; more or less crystalline ; colour black, or blackish-brown. Both the bituminous and carbonaceous shales graduate on the one hand into argillaceous shale, and on the other into coal. The former merges DEEIVATE fl6cs. 115 into Cannel, and the latter nnto^ Cubn,. N \H ie sub- varieties a and b are bituminous, while c, d, and e are non-bituminous. Some bituminous shales are impure coals ; that is, they are capable of being used as fuel, while the poorer kind will not con- tinue to burn in the fire, but become ash, the " slate " of the coal-merchant. Burning and lubri- cating oils, illuminating gas, &c., can be procured from many of the Bituminous shales. In general the Carbonaceous shales are not of much value ; a few, however, when mixed with, anthracyte, make a strong and lasting fire. Local Terms for Bituminous Shale. a. Batt and Bass (Staffordshire), (b.) Daubs. Local Terms for Carbonaceous Shale. c. Kelve (Leinster), (d.) Pindy (Cork), (e.) Slaty Culm (Limerick and Clare). NOTE. The other coals, such as Peat, Lignyte, and Black Coal, are classed and described among the SUBAERIAL ROCKS (page 122) ; they having accumulated on the surface of the earth, prior to having been buried and covered by more recent deposits. B. LIMESTONE. A more or less crystalline aggre- gate of calcite, in association with a greater or less quantity of carbonaceous, argillaceous, and arenaceous matter; compact, porous, fissile, amorphous, or oolitic ; very variable in colour. Some limestones are made up almost entirely, others only partially, of shells, fragments of shells, corals, madrepores, and such-like; others for the most part are due to the precipitation of lime held in solution by water ; while some in a great mea- sure are mechanically formed, preexisting calcareous 116 HANDY-BOOK OF ROCK NAMES. rocks having been denuded away and the detritus deposited in water. Limestones in general, however, appear to be more or less due to a combination of two or more of these modes of formation. Limestone may contain magnesia, silica, alumina, bitumen, ores of iron, &c., either as mechanical ad- mixures or as chemical deposits, in conjunction with the carbonate of lime ; and the presence of such mine- rals occasions many varieties in colour as well as com- position. Of limestone Jukes writes : " Varieties of limestone occur in different localities, both geogra- phical and geological, peculiar forms of it being often confined to particular geological formations over wide areas ; so that it is much more frequently possible to say what geological formation a specimen was derived from, by the examination of its litho- logical characters, in the case of limestone, than in that of any other rock." NOTE. The colour of many, if not of most, limestones seems due, in a great measure, to the ores of iron chemically or mechani- cally contained therein. Dark blue or blackish limestones, when followed to a good depth, are nearly always found to be of a greenish colour. Eed and variegated limestones in depth are generally grey or dove-colour, while all yellowish limestones, when in their normal state, have a greenish shade, no matter how pale. a. Compact Limestone. Homogeneous and fine- grained; fracture sometimes uneven, but ge- nerally conchoidal, either earthy or smooth ; may be argillaceous, siliceous, magnesian, or ferruginous. b. Crystalline Limestone. An aggregate of crys- tals of calcite, fine or coarse, in association with argil, silica, and the like. Typical Crystalline limestone belongs to the me- DERIVATE ROCKS. 117 tamorphic rock series ; nevertheless, most sedimen- tary limestones are more or less crystalline, some being aggregates of large well-developed crystals. Jukes found the limestone forming the " great bar- rier coral reef," Australia, "to have a crystalline structure internally." c. Marble [Lat. marmor'] . Any limestone capa- ble of being cut and of taking a fine polish. Marbles may be unicoloured, such as pure black, white, grey, &c. ; or they may be particoloured) deriving their colour from contained minerals or animal remains. Homogereous rocks, both as to texture and hardness, cut more evenly and take finer polish than other?, and make the better marbles. The names by which marbles are known are very various ; some are called after the localities in which they are found ; others after their colour or the shells they contain, or any other peculiarity that may give a character to a rock. d. Oolyte, or Oolite [Gr. oon, an egg, and lithos, a stone], Roestone. Spheroidal concretionary structure, having the appearance of the egg or roe of a fish. Subvarieties are (a.) Pisolyte, or Pisolite [Lat. pisum, a pea] ,. Peastone, which has a resem- blance to an agglutination of peas ; and (b.) Dolomitic Oolyte, there being minute sphe- roids of dolomite in a limy matrix. Each concretion is formed of numerous concentric layers, being sometimes hollow at the centre, or it may inclose a minute particle of sand or other mineral substance. 118 HANDY-EOOK OF EOCK NAMES. NOTE. Oolitic rocks are typical of one of the Secondai-y geological groups, which has been given the name of the Oolitic formation. This structure, however, occurs in other groups, but more especially in the Carboniferous limestone. e. Chalk [Lat. calx, lime] . Usually a white or whitish fine-grained rock, but sometimes greyish, or even red; often earthy or pul- verulent, but sometimes hard and compact. Subvarieties are (a;) Indurated chalk, called White limestone in Ulster. Jukes thus describes it : " Considerably harder and firmer than the friable rock which is commonly known as chalk.-" (b.) Chalk-rock (Whitaker), a siliceous variety ; (c.) Pisolitic chalk, or Maestricht, which has a minutely spheroidal structure; (d.) Glauconitic chalk, greenish from contain- ing glauconite ; and (e.) Ferruginous or Red chalk, coloured red by oxide of iron. . /. C&lfcfiinter, or Calcareous Tufa, a loose and friable variety of calcite deposited from water charged with lime. Subvarieties are (a.) Travertine, (b.) Staladyte, (c.) Stalagmyte, and (d.) Rock-meal. When compact, hard, and semi-crystalline, it is called Travertine ; if deposited in long mam- millated and pendent masses from the roof of a cave or fissure, Stalactyte [Gr. stalactis, that drops] ; while the boss formed on the floor of the cave or fissure from the lime in the water which dropped, is named Stalagma [Gr. stalagma, a drop] . Rock-meal is a white and light calc-sinter that becomes powder on the slightest pressure. g. Coral-reef Limestone. Limestones in course of formation, consisting of corals, shells, and DERIVATE ROCKS. 119 calcareous sand or mud, often more or less crystalline. Ji. Brecciated Limestone, Limestone "Breccia, and i. Limestone Conglomerate, or Pudding stane. A rock that has an appearance as if fragments of limestone had been dropped into a lime- stone matrix. If the contained pieces are of different colours from the base, and the latter contrasts well, the result is often a handsome rock; the inliers are usually purer than the matrix, and weather more freely, giving the exposed surfaces of the rock a cellular tissue. If the inliers are round or roundish, the rock is called Pudding stone Limestone. j. Ruhbly Limestone. A limestone made up of round or roundish irregular lumps and ag- gregates of lumps of various sizes, separated from one another by shaly partings, the latter being more or less calcareous.* Limestones may also be called PebWy* or Conglo- meritic, Tuffose, Shaly, Slaty, -Geodic, Cellular, or Porous, if any of these structures extend over a considerable portion of the rock and give it a marked character. k. Lithography te 9 Lithographic Stone [Gr. lithos, a stone, and grapho,! write], A very even- grained, compact, fine limestone, usually buff or drab-colour, employed in lithography. Other varieties are, /. Siliceous Limestone, m. Cherty, n, Argillous, o. Arenaceous, p. Fer- * At Oughterard, Galway, Ireland, there are remarkable beds of Pebbly limestone, full of quartz fragments, generally of the size of large shot, and rarely larger than a pea. 120 HANDY-BOOK OF EOCK NAMES. ruginous, g. Bituminous, r. Stinkstone, or Swinestone, or Fetid Limestone. If silica is diffused throughout the lime, the rock is siliceous ; but if the silica is in separate nodules, concretions, or layers, the rock is clierty ; while, if particles of sand are present, the rock is arenaceous. Cherty and argillaceous limestone, as also some kinds of siliceous limestone, when weathered, lose these calcareous portions, the resi- due being called Rotten-stone. Many bituminous limestones, when struck or rubbed, emit an odour of sulphuretted hydrogen gas, and these have been called by the different names of Stink-stone, Swine- stone, and Fetid Limestone. Important varieties are, s. Dolomitic, and t. Hydraulic Limestone, or Cement-stone. Hydraulic limestones are more or less dolo- mitic ; they contain from 10 to 30 per cent, of silica, alumina, and magnesia. Some contain ores of iron, which are rather prejudicial than otherwise to their economic value. Hydraulic limestone, when burnt, yields a lime that does not slake when water is added, but forms a mortar which will set under water. According to Dana, some hydraulic limestones should be classed as Dolomytes. C. DOLOMYTE, Dolomite (after M. Dolomieu), Mag- nesian Limestone. An aggregate of dolomite (bitter spar), combined with some calcite ; usually also with more or less iron, some silica, alumina, &c. The mineral Dolomite contains carbonate of lime, 54'35 ; carbonate of magnesia, 45'65 (Dana). DERIVATE EOCKS. 121 The rock Dolomyte, according to Cotta, must con- tain 23 per cent, of carbonate of magnesia; while those calcareous rocks in which there is less than this amount should belong to the limestones. Dolomyte is often geodic and vuggy, or con- taining numerous drusy cavities. The geodes and the lining of the cavities are usually crystalline (Bitter spar), and not uncommonly contain one or more isolated crystal or crystals of quartz (Rod' crystal). NOTE. Dolomyte belongs to both the Ingenite and the Derivate orders of rocks ; as some are due to metamorphism, while others were formed by the contemporaneous deposition of the carbonates of lime and magnesia, forming a Dolomyte or Magnesian limestone. Dolomyte varies in texture. It may be, a. Granular, b. Oolitic, c. Compact, d. Porous, e. Cellular, f. Concretionary, g. Brecciated, or h. Rubbly. It also varies in composition, and may be, i. Ferruginous, j. Argillous, or earthy ; If. Arenaceous, or sandy ; I. Siliceous, m. Clierty, and n. Tvffose; they being analogous to the previously described varieties of limestone. It weathers into o. Dolomitic sand. NOTE. Cotta appears to be of opinion that Dolomyte is never oolitic. This however seems erroneous, as among the Carboniferous limestone in the cos. Limerick. Mayo, &c., Ireland, subordinate beds of Oolitic dolomyie occur. In Limerick minute spheroids of dolomite are disseminated in a calcitic matrix ; while in Mayo the spheroids, as well as the base, are dolomitic or dolomyte. 122 HANDY-BOOK OF ROCK NAMES. Class II. SUBAERIAL EOCKS. [Lat. sub, under; aer, lower air]. Rocks that were formed on the surface of the earth. Most of these, however, subsequently were covered by, or buried under, newer-formed strata, which may be either subaqueous, subaerial, or igneous. D. Mechanically, chemically, and organically-formed Rocks. Subaerial rocks are due to mechanical, chemical, or organic action, or two or more of these combined. The major part, however, in- cluding the principal rocks of the group, are more or less due to the growth and decay of organic matter, united with chemical action. A. COAL. This geologically includes and signifies all rocks, recent or otherwise, that can be ignited and kept burning without the addition of any other substance. NOTE. The burning properties of some coals can be im- proved by the addition of other substances, as of water to anthracyte ; nevertheless, all rocks that are classed as coal should be capable of burning by themselves. a. PEAT, Turf, Bog [Celtic ? peait or puit, a soft miry substance]. An aggregate of organic matter more or less solidified, or indurated and mineralized ; colour w r hitish-brown, yel- lowish-brown, blackish or yellowish white. Subvarieties are (a.) White Turf, (b.) Broivn Turf, (c.) Black, or Stone Turf, (d.) Gas or Candle Turf. Peat, or Bog, varies in appearance and texture, according to the position in which it is situated, DEEIVATE ROCKS. 123 and the rate at which the accumulation was made. On low, flat land it grows much more rapidly than on hills or hill-slopes ; consequently on the low land the peat is quite different from that on the hills, and in Ireland they are classed as Low-bog, or 13 awn* and Mountain-bog. The Low-bog gives (a.) White Turf, (b.) Brown Turf, and (c.) Slack, or Stone Turf; while the Mountain-bog only gives (b.) Brown, and (c.) Black Turf. On both there is an un- profitable surface or " clearing " (more or less living organic matter), which varies in thickness ; on the former ranging from three to six feet in depth, while on the latter it rarely exceeds twelve inches in thickness. Peat may be fissile, but more generally it is felt-like, the vegetable remains being interwoven, and forming a tough mass. The fissile texture of subaerial peat is due to vegetable growth ;f each annual growth forming a separate layer. This is more common in some bogs than in others. White turf is a nearly pure, if not an entirely pure, organic substance, and when burnt has little or no ash. Brown turf is always more or less * Bawn (Anglice white), so called from the white appearance the dead moss, grass, &c., have during the major part of the year, compared with the colour of the grass land and tillage in the vicinity. f There are fissile peats in which the texture is caused by lamination, peat masses being denuded and subsequently de- posited. Such peats, however, are not Subaerial, but are Subaqueous Eocks, and they are often interstratified, or mixed with clay, sand, or the like. Extreme heat or frost will break up peat, and leave it ready to be denuded and carried away by wind, or " rain and rivers," to be deposited in hollows, lakes, and such other reservoirs. 124 HANDY-BOOK OF EOCK NAMES. mineralized; while Black, or Stone turf, is a cheinico-organic rock, often containing such mine- rals as pyrite, marcasite, and the like ; when burnt, it leaves a considerable residue or ash ; sometimes it is semi-crystalline, and often it is scarcely dis- tinguishable from Lignyte. NOTE. The residue or ash of peat attains its maximum in the deepest portions of the bog ; thus Stone turf will have more ash than the overlying Brown turf, and the latter than the White turf ; while the subordinate parts of each have re- spectively more ash than the portions above them. The plants growing on the surface collect their inorganic food from the atmosphere, and after their decay, the mineral substances are being continually carried downwards by the water that per- colates through the mass, the lower portions thereby becoming the most impregnated : some impurities also come up in water from springs. Gas peat, or Candle turf, is not very common. It was found in a mountain bog on the island of Valencia, Ireland; was of a dirty yellowish-white colour ; had the consistency of soap ; when dried was very inflammable, and burned with a clear, bright, steady flame. Peat accumulations are usually surface rocks, that is, rocks still growing at the surface, and being added to at the present day ; it has, however, been found under drift and other surface deposits. JEolian drift may be blown over it; on a sunken coast-line it often is found under Marine drift ; while in some places it has been found under Boulder-clay drift. NOTE. Cotta mentions peat in Germany " covered by diluvial loam/' Oldham records peat " under a considerable depth of drift," near Nenagh, co. Tipperary, Ireland. Other Irish localities are the Boleyneendorrish valley, near Gort, co. Galway, under 25 feet of boulder-clay drift ; and Newtown, Queen's co., under a thickness of 96 feet. The latter is three DEEIVATE ROCKS. 125 feet thick, compact, solid, semi- crystalline, very bituminous, and blazing like a candle when lighted. It might almost be classed as lignyte. b. Lignyte, or Lignite, Brown Coal [Lat. lignum, wood]. Fissile or compact; woody or earthy ; usually brown or black ; streak brown ; very inflammable, burning with much, smoke and smell. A non-caking coal. a. Woody Lignyte, (b.) Compact Lignyte. Fremy has divided lignyte into two kinds; 1st, Lignyte that still displays woody structure, and 2nd, Lignyte exhibiting the aspect and compact- ness of soft coal. c. Jet [Jayet, Gagates, after Gagas, a place in Lydia, Asia Minor]. "A black variety of brown coal, compact in texture, and taking a good polish." Dana, NOTE. Jukes considers jet as a sub variety of cannel coal, while Page supposes it "is rather a species of amber than coal." c. Black Coal, SteinJcohle, Common Coal, Pit Coal. A black, brownish-black, or greyish-black, compact or semi-compact mass, occasionally iridescent ; lustre dull to brilliant, and either earthy, resinous, or submetallic ; opaque ; fracture conchoidal to uneven. Subvarieties are (a.) Caking Coal, (b.) Non- caking Coal, (c.) Cherry or soft Coal. Mineral coal, according to Dana, should be " compact, massive, without crystalline structure or cleavage ; sometimes breaking with a degree of regularity, but from a jointed rather than a cleavage 126 HANDY-BOOK OF EOCK NAMES. structure." Black coal may be a caking or a non- caking coal ; the latter is sometimes called Cherry or soft coal. Caking coal softens and becomes pasty or semi-viscid in the fire, also it is inclined to form clinkers or to become welded together. Cherry or soft coal burns freely without softening, or any ap- pearance of incipient fusion. d. Anthracyte, or Anthracite, Stone Coal [Gr. anthrax, carbon] . Non-bituminous coal ; lustre bright, often submetallic, and fre- quently iridescent ; conchoidal, sharp-edged, shining fracture, or breaking readily into small cubical lumps. Anthracyte appears not to be a normal rock, but to be an altered bituminous coal, from which the bituminous qualities have been extracted or ex- pelled ; sometimes it is an associate of Metamor- phic rocks , but it also is found interstratified and associated with unaltered rock. NOTE. In Munster, Leinster, and Connaught, Ireland, anthracyte is interstratified with fossiliferous grits, shales, chinch, and fire-clay, the ordinary associates of bituminous coal, and these strata are not altered, except perhaps that they are more siliceous and harder than the ordinary coal-measure rocks in other countries. In places they are also cleaved. A rock allied to Anthracyte is Native colic. It is undoubtedly an altered rock, due to the irruption of igneous rocks into beds of coal. Native coke is harder and more solid than artificial coke. B. SURFACE DEPOSITS AND ACCUMULATIONS. These may be peaty, clayey, sandy, gravelly, shingly, or a combination of two or more. a. Boulder-clay Drift, a clayey or sandy-clayey matrix, sometimes calcareous, inclosing DERIVATE EOCKS. 127 more or less rounded, polished, grooved, scratched and etched blocks and fragments of one or more kinds of rocks. Subvarieties are (a.) Calcareous or Corn-gravel, (b.) Argillous, or Till, and (c.) Arena- ceous. Boulder-clay drift in general partakes more or less of the nature of the subjacent rocks, with a greater or less admixture of blocks .and fragments of foreign derivation. The calcareous variety in Munster is called Corn-gravel, being used as a manure for corn-land, while the red argillous variety in Ulster is known as Till. b. Moraine Drift, Boulder Drift , an accumulation having a more or less sandy, clayey, or gravelly matrix, containing angular or sub- angular, rarely rounded blocks and fragments of the adjacent rocks, foreign materials being in subordinate quantities. Subvarieties are (a.) Calcareous, (b.) Argillous, (c.) Arenaceous, (d.) Rocky. Moraine drift when in low valleys often graduates into shingle, gravel, and sand, while on hill- slopes it may pass into Rocky -moraine drift, full of large angular blocks, often tons in weight. c. Sand, gravel, and shingle, usually more or less stratified ; sometimes containing thin beds or layers of clay ; at times the materials are heaped confusedly together. Subvarieties are (a.) EsJcer [Celtic, ridge], Kaim [Celtic, Kam, winding], As or Os Drift (Scandinavian), (b.) Post-drift Gravel. 128 HANDY-BOOK OF ROCK NAMES. NOTE. Boulder-clay and Moraine drifts are due to glacial or ice action, and therefore may be considered subaerial accumula- tions, even although some of the first may have been deposited in the sea or a lake. Esker drift seems to be either of the pre- viously mentioned drifts, well washed, seemingly by marine or tidal currents. Some writers, while describing Asar and Kaims, evidently have included with them the " drumlins " or ridges of boulder-clay drift, which are quite distinct. The subvarieties (a and b), though not Subaerial Rocks, are yet described here, on account of their connection with the other Surface deposits and accumulations, (a) is probably of marine origin, while (b) may be marine, lacustrine, or fluviatile. c. Beaches. Sand, gravel, or shingle ; often shelly. Beaches usually occur in more or less level ter- races, on account of their marking the margins of present or ancient seas or lakes. d. j^Eolian Drift or Sand, Quartzose or Rabbit Sand; (e.) Shell or Calcareous Sand. Fine incoherent sand : the first subvariety, when normal, is entirely composed of siliceous particles. In the neighbourhood of the sea it is more or less mixed with shells, corals, and such-like, or may graduate into shell sandy a calcareous accumulation of the debris of corals, shells, madrepores, and the like, sometimes containing as much as ninety per cent, of limy matter. All these sands are also called Blowing sands, and are of various thicknesses up to hundreds of feet. Both .^Eolian drift and Shell sand may have been originally subaqueous, but their present arrange- ment, form, and character, are due to subaerial action. Some collections of ^Eolian drift, such as that of the Sahara, in Africa, seem to have been originally produced by marine action, as they occupy lately- DERIVATE ROCKS. 129 raised sea-basins. Other accumulations may be caused by meteoric abrasion; frost, heat, and che- mical action disintegrating arenaceous rocks. But large quantities of it would appear to be glacier- formed, being due to the grinding of ice-bound rocks one against another, or the bottom and sides of valleys, forming sand or silt, that subsequently was carried down by a glacial river and deposited either in a lake or sea, at or near the mouth of a river. Such sands, when afterwards raised to form dry land, if in sheltered situations, would in time be clothed with vegetable mould ; but if in exposed situations, they would be wafted hither and thither by every gust of wind, forming the ridges and hil- locks known as Sand-dunes (Celtic, doon, hill). At or near the mouth of most of the valleys in Ireland, which in prehistoric times were occupied by ice-streams, whether inland or on the seaboard, these accumulations of sand are found. In the plain of Limerick, at Killon&n, opposite the mouth of the valley called Glencoloo, these sands have been proved to be over 200 feet in thickness. f. Bergmehly Mountain-meal. An exceedingly fine earth, covering extensive tracts of coun- try in Sweden, composed of microscopic sili- ceous shells, said by T. Rymer Jones to be due to a lake deposition. d. Guano. Accumulations of animal excrement and remains ; more or less compact ; some- times semi-crystalline ; very fetid ; yellow, brown, or blackish-brown in colour. e. Soil, Vegetable Mould, earthy, sandy, or peaty. Due to the combination of meteoric action with vegetable growth and decay, along with the work of certain animals. 130 ' HANDY^BOOK OF EOCK NAMES. Any portion of the: surface of the ground, if de- prived of its vegetal)! e soil, unless subject to ex- tremes of heat or cold, or some such obstructive action, will in time regain its coating of soil. At the first, meteoric action disintegrates and amelio- rates the surface, to prepare it for the growth and decay of vegetables ; after which, as pointed out by Darwin and others, the operations of earthworms, ants, and such-like, accelerate the formation of soil . Local Names for some Wine-growing Soils. Albarizo (Sicily), a yellowish-whitish chalk-soil, consisting of lime, argil, and oxide of iron ; an absorbent, spongy substance, loose, always fresh and open, not caking. Barro (Sicily), sand mixed with a clayey earth and gravel. Arena (Sicily), sand on which the vine thrives well and produces abundantly, but the grapes make a thin wine. Biigeo (Sicily), a blackish aggregate of clay, vegetable earth, and gravel. Pedra Molla (Madeira), soft rock-debris, which never becomes a fine mould, but is generally in a crumbly state, like small coal ; in this surface-deposit the vines are planted. NOTE. All rocks, whether tenacious, like granite, grit, lime- stone, and the like, or fragile, like drift and the other sarface accumulations, weather more or less freely when exposed to the atmosphere. If circumstances allowed such weathered portions to remain, a soil of a greater or less thickness would gradually form. In many localities, however, the detritus, as fast as it is formed, is carried away either by wind or rain and rivers, while in most other places more or less is removed prior to a protecting envelope being formed by the growth and decay of vegetation ; and even after the envelope is complete, some of the earth, continually being brought to the surface by earth- worms and the like, will be removed by wind and water. /. Meteoric Drift, Clay, Sand, Gravel, and Shingle, Meteorites. DERIVATE R0m 5b LIB ^gVl31 Under peculiar circumstai surface rocks that can sca are formed by meteoric abrasion ; sEaly si aTes, some limestones, and certain ingenite rocks weather into clays ; arenaceous and some ingenite rocks will pro- duce sands, while certain limestones, conglomerates, breccias, and the like, weather into a coarse shingle or gravel. Meteorites in a few places, as in Green- land, form surface deposits. NOTE. In Brazil, Agassiz and others have noted the vast thickness of meteoric drift formed in situ by extreme heat ; while in Ireland, in many places on the extensive crags or flats of carboniferous limestone, a coarse shingle, more or less angular, is formed by the weathering of the rock. g. Ice may be compact, granular, fibrous, or laminated. Firn, or Neve, is the accumulation above the " snow-line," which becomes consolidated into gra- nular ice. Glacier ice is indistinctly granular, with its lamination more or less contorted or even effaced. Ice that forms in crevasses is compact, while Cave ice may have interstratified beds of sand in it. ALPHABETICAL INDEX to Local, Duplicate, and other Eock names, that do not appear in the Classified List, Part I. ; the Local names being printed in Italics. In the second column are the names of the Rocks, under which the others will be found in Parts II. and III. Agalmatolyte Onkosin 93 Albarizo Soil 130 Amphibolic Gneiss Hornblendic Gneiss 78 Amphibolic Limestone Hemitrene 90 Amphibole Schist Hornblende Schist 87 Anamesyte Aphanyte-Dioryte 60 Anorthosyte Noryte 59 Anorthyte ... Dioryte 59 Arena ... Soil 130 Argillous Schist Argillyte 81 As Drift Esker Drift ... 127 Augitic Diabase Pyroxenic Diabase 57 Ball Elvanyte Pyromeride 43 Ball Porphyry Pyromeride 43 Barro Soil 130 Basalt Aphanyte-Doleryte 56 Basalt Augyte 73 Base, or Mother-rock Elvanyte 40 Base, or Mother-rock Granitoid Elvanyte 43 Basic Tuff Whinstone Tuff 67 Bass Batt 115 Bind Shale 106 Binder Grit 99 Bitumen Asphalte Ill Bituminous Marl Oil-slate 102 Black Turf Stone Turf 123 Blowing Sand ^Eolian Drift 128 134 INDEX. BlueKock Shale 106 Bog Peat 122 Boghead Cannel Torbanyte 114 Boghead Mineral Torbanyte 114 Boulder Drift Moraine Drift 127 Brash Sand and Gravel 95 Brass Balls ... Grit 99 Brass Binders Grit 99 Brick-stone Lateryte 101 Brown Coal Lignyte 125 Brown Stone ., Grit 99 Buddagh Fire-clay 100 Bugeo Soil 130 BulVs-eyes Slate 106 Bury Shale 106 Calamine Galmey 112 Calcareous Clay Marl 102 Calcareous Sand Shell Sand 128 Calcareous Schist Spilyte 81 Calcareous Tufa Calcsinter 118 Calliard Grit 99 Candle-turf Gas Turf 122 Catsbrain Sandstone 98 Catshead Grits 99 Cellular Limestone 119 Cement-stone Hydraulic Limestone ... 120 Clay-ironstone Spherosideryte 110 Clay-schist Argillyte 81 Clay-slate Slate 103 Clinkstone Phonolyte 72 Clod Cannel Coal 113 Coal-clay Fire-clay 100 Coal-seat 100 Common Coal Black Coal 125 Common Ophyte Ophy te 63 Compact Augyte ... Basalt 74 Concretionary Mica-schist . . . Knotty Mica-schist 86 Cone-in-cone Marl Tutenic Marl 103 Corn Gravel Calcareous Boulder - clay Drift 127 Cream Ophyte 90 Crow-stone Grit 99 DiallageKock Gabbro 58 Doab Clay 100 INDEX. 135 Doleryte Augyte 73 Epidote Kock Epidosyte 65 Fekes Shale 106 Felstone Tuff Felsyte Tuff 67 Felsite Kock Felsitic Granite 30 Felsyte Felstone 44 Felsyte Petrosilex ... 45 Ferruginous Oligoclase Granite Hematitic Oligoclase Granite 33 Ferruginous Tuff Hematitic Tuff 68 Fetid Limestone Stinkstone 120 Flag Flagstone 98 Flaggy Euryte Slab Euryte 50 Flos Ferri Aragonite 112 Flucan Shale 106 Foliated Granite Gneissoid Granite 34 Foundation Gravel ' 95 Freestone Sandstone 99 Friable Marl Mealy Marl 102 Friction Breccia 62 Frilled Argilly te Folded Argillyte 82 Furbogh Granite Titan itic Granite 33 Galliard , Grit 99 Galway Granite Porphyritic Oligoclase Gra- nite 34 Ganistor Clunch 101 Garnetiferous Limestone ... Calciphyre 89 Geodic Limestone 119 Glassy Actinolite Rock ... Actinolite Kock 62 Gneissic Granite Gneissoid Granite 34 Gneissoid Felstone Gneissyte 54 Grandt Sandstone 99 Granitic Porphyry Elvanyte ... 39 Granitone Gabbro 58 Granular Felsyte Schist ... Gneissoid Felsyte Schist... 85 Granular Quartzyte Quartz Kock 84 Gravel ' Shale 106 Greenstone Whinstone 55 Greenstone Tuff Whinstone Tuff 67 Grey Gneiss Common Gneiss 78 Greystone ..> Trachy-doleryte 73 Hardseat Clunch 101 Hazel Sandstone 99 Hone 'Novaculyte 105 Hybrid Kocks 49 136 INDEX. Hypersthenyte Hyperyte 59 Jacotinga Itabiryte 83 Jasper Quartz 88 Kaim Drift Esker Drift 127 Killas Shale 106 Labrador Rock Noryte - 58 Labradoritic Augyte Common Augyte 74 Lagen Gneiss Eibaned Gneiss 79 Lapis Lydius Basanyte 109 Leaf Clay Book Clay 102 Leaf Marl Book Marl 103 Leinster Granite Intrusive Granite 27 Leptinyte Felsyte Schist 85 Leucite Rock Leucilyte 74 Limestone Breccia Brecciated Limestone ... 119 Lithographic Stone Lithograpbyte 119 Maestricht Pisolitic Chalk 118 Magnesia Schist Rhaetizitic Schist 87 Magnesian Limestone Dolomyte 120 Mealy Felstone Friable Felstone 50 Met'al Shale 106 Mica-trap 48 Micaceous Diabase Kersantyte 58 Micaceous Dioryte Kersanton 60 Micaceous Felstone Minette 47 Micaceous Hornblende Rock Mico-hornblende Rock ... 63 Micaceous Limestone CipolHno 89 Micaceous Quartzyte Itacolumyte 82 Mineral Pitch ... Asphalte Ill Moorhead Rock Topanhoacanga 110 Moss Serpentine Pyralloly te 93 Mountain Meal Bergmehl ." 129 Obicular Dioryte Napoleony te 60 Oelschiefer Oil-slate 102 Oilstone Novaculyte 105 Omey Granite Intrusive Oligoclase Granite 34 Ophiolyte Ophyte 91 Orthophyre Felstone Porphyry 51 Os, or As Drift Esker Drift 127 Ottrelitic Schist ... Phyllitic Schist 81 Oughterard Granite Intrusive Granite 27 Pausilippo Tufa Pumiceous Tufa 75 Pearl-stone ... Perlyte 71 Pea-stone Pisolyte 117 INDEX. 137 Pebbly Limestone 119 Pedra elastica Itacolumyte 82 Pedro, molla Soil 130 Peldon Grit 99 Pencil Pencil-slate 105 Peridolyte Eukyte 56 Phyllitic Argillyte Phyllistic Schist 81 Pinsill Pencil-slate ... 105 Pipe-clay Potter's Clay ... ..'. ... 100 Pitchstone Felsyte Felstone Glass 46 Pit Coal Black Coal 125 Plate Shale 106 Plutonic Breccia ... Brecciated Tuff ... ... 69 Plutonic Conglomerate ... Conglomeritic Tuff 69 Pontellaryte Compact Elvanyte 42 Porcelain Clay Kaolin 65 Porous Limestone 119 Porphyrite Euryte 49 Porphyritic Leucily te ... ... Leucitophyry '. . 74 Porphyry Felstone Porphyry 51 Post Grit 99 Precious Ophyte Ophyte 63 Puddingstone Limestone ... Brecciated Limestone ... 119 Purniceous Sand Pumiceous Tufa 75 Pyrito-carbonaceous Schist . . . Carbonaceous Schist ... 81 Quartz Porphyry Elvanyte 39 Quartz Schist ... Quartzyte 82 Quartziferous Felstone Quartzitic Felstone 46 Quartziferous Porphyry . . . Elvanyte 39 Quartzitic Granite Greissen 30 Quartzose Felstone Quartzitic Felstone 46 Quartzose Sand ^Eolian Drift 1 28 tiabbitSand :. jEolian Drift 128 Eaddle fceddle 110 Red Chalk Ferruginous Chalk 118 Red Free Sandstone 99 Eed Gneiss Gneissyte 54 Eed Ochre Eed Iron-mould 110 Eibaned Quartzitic Felstone Striped Quartzitic Felstone 47 Eipidolitic Elvanyte Chloritic Elvanyte 42 Eipidolitic Euryte Chloritic Euryte 49 Eipidolitic Gneiss Chloritic Gneiss 78 Eipidolitic Gneissyte Chloritic Gneissyte 54 Eipidolitic Granite Chloritic Granite 33 138 INDEX. Ripidolitic Quartzitic Felstone Chloritic Quartzitic Felstone 47 Kipidolite Schist Chlorite Schist 87 Eock Grit 98 Eock-Und Shale 106 Rock-salt Halyte 107 Roe-stone Oolyte 117 Eotch Sandstone 98 Rottenstone 120 Bubble Gravel 95 Eucks Slate 106 Saccharoid Limestone Statuary Marble 90 Scandinavian Granite Basic or Oligoclase Granite 32 Schistoid Felstone Foliated Felstone 51 Schorl Schist Tourmaline Schist 87 Scorious Leucityte Leucityte Lava 74 Seat Fire-clay 100 Seat-clay Fire-clay 100 Sepiolyte Meerschaum 65 Serpentine Ophyte 63,91 Shaly Limestone 119 Shingle Shale 106 Shingly Felstone Rubbly Felstone 50 Schistoid Felstone Foliated Felstone 51 Siliceous Elvanyte Quartzitic El vanyte 41 Slabs Slab Slate 98 Slaty Felstone Cleaved Felstone 51 Slaty Limestone 119 Slig Shale 106 Sliggeen Shale 106 Soapstone Steatyte 64 Soft Coal Cherry Coal 125 Soft-seat Fire-clay 100 Sparry Gypsum Selenyte 108 Spathic Gypsum Selenyte 108 Spavin Fire-clay 101 Spheroidal Mica-schist . . . Curled Mica-schist 86 SplentCoal Splint Coal 114 Spotted Quartzitic Felstone... Yariolitic Quartzitic Fel- stone 47 Strangel Gneiss Fibrous Gneiss 79 Striped Felsyte Ribaned Petrosilex 46 Stone-coal Anthracyte 126 Stone-turf Black Turf 123 Stone-bind Shale 106 INDEX. 139 Stone-mine Grit 99 Stonefield Slate Roofing Slate 105 Swine-stone Stinkstone '.. 120 Thickly-jointed Felstone ... Kubbly Felstone 50 Till Argillous Boulder - clay Drift 127 Tosca Pumiceous Tufa .' 75 Touchstone Basanyte 109 Trachyte Porphyry Liperyte 70 Trass Pumiceous Tufa 75 Tuffose Limestone 119 Turf Peat 122 Underclay Fire-clay 100 Vegetable Mould Soil 129 Verd-antique Ophyte 91 Vesicular Augyte Basalt Lava 74 Vesicular Lencityte Leucityte Lava 74 Vesicular Obsidian Pumice 71 Vesicular Trachyte Trachyte Lava 73 Vitryte ... . Opal 112 Whetslate Novaculyte 105 Whetstone Novaculyte 105 White Limestone Indurated Chalk 118 White-stone Felsy te Schist 85 Yellow Ochre Yellow Bog-iron Ore ... 109 WYMAN AXU SONS, PRINTERS, GREAT QUEEN STREET, LONDON, W.C. K O CN i CN C* CQ CO O in u iu u X CN 10 IU 8F RETURN TO* ^ Z LU S zi < - g ^ 8 >- (D < Jj K 1 ^ Q} rv c LU | u_ <^ g < J OQ LU 15" O 1 UJ H >- ^ w/ < _ ^ u 0) (/) -2 LU O | O 3! 3 Q CD c ! _i^ 1 1