'm ' A*K *x ^4i*~vi ~\s* / Mi- IX SKETCH OF A BRITISH MINERALOGY. CLASS I. COMBUSTIBLES. ORDER I. HOMOGENEOUS. 'Genus 1. Calor 2. Hydrogen 3. Nitrogen 4. Oxygen 5. Phosphorus 6. Sulphur 7. Carbon 8. Fluoric Radicle 9. Muriatic Radicle 10. Boracic Radicle ORDER II. COMPOUND, Genus 1. Bitumen 2. Ammonia 3. Soda 4. Potash 5. Carbo oxygeriizatus ORDER III. AGGREGATE? CLASS II. EARTHS. ORDER 1. HOMOGENEOUS. Genus 1. Argilla 2. Magnesia 3. Calx 4. Silex 5. Strontia _ Q. Barytes 7. Zirconia 8. Glucina g, Yttria 10. Agustina, ORDER II.. COMPOUND. Genus 1. Argilla 2. Calx carbonata 3. - sulphata 4. Quartzum ORDER III. AGGREGATE, CLASS III. METALS. ORDER I. HOMOGENEOUS. Genus 1. Molybdenum 2. Tellurium 3. Uranium 4. Antimonium 5. Manganesium' 6. Zincum 7. Stannum 8. Ferram 9. Cobalt ura 10. Cuprum 11. Arsenicum 12. Niccolum 13. Wisruutum. 14. Argentum 15. Plumbum 16. Mercurium 17. Tungstenum, 18. Aurum 1Q. Platinum 20. Titanium 21. Columbium 22. Tantalium 23. Chroraum 24. Iridium 25. Osmium ORDER II. COMPOUND. Genus 1. Ferrumoxgygenizatun^ XI OBSERVATIONS ON THE SYSTEM. CALOR*, or matter of heat, see p. 1. We left out the termination ic } because it is not known to be an acid, which is in general signified by that termination. It is placed as the first Genus, from its universality 9 at the same time we may say it will seldom be joined as the characteristic of a species. The other Genera are placed according to their gravity, and it may not be amiss to say that HYDROGEN is the inflammable part of water, and the next Genus, NITROGEN, is a part in the composition of atmospheric air, which, without the wholesome genus placed next to it (Ogygen) being combined with it, would be unfit for respiration. PXYGEN is the other component part of water. PHOSPHORUS is combustible at the temperature of the common atmosphere, and is in nature sometimes combined with Lime and Earths and Metals, as Phosphate of Lime, and Lead see p. 173 frequently found also in animal slime, and bones. *. We have placed the lightest first, as appearing; mpst natural xii SULPHUR is well known in the form of Brimstone, and ii found native, or with Earths, Metals, &e. FLUORIC ACID, whose base is not known, is commori with Lime see Fluate of Lime, p. 151. These seven last form gases or acids* with Calor. The MURIATIC RADICLE may assist in forming salts see Muriate of Soda, p. 51. The BORACIC RADICLE is sometimes in combination with the Alkali f Soda. These, in the order Compound, form Species. Their powerfulness and various combinations being well known, there will be ample field for the Geologists to spe- culate upon j and they may shake hands together, who were adverse advocates on account of the Volcanian and Neptunian Systems. Some of the Genera and Species are not properly num- bered, as in the beginning of the Work we could not find a sufficiently regulated System, and many of the Species are yet so little known, that their numbers cannot be certain, i> lfcj * Changing vegetable blue red. f Changing vegetable blues greeu. *' ' BRITISH MINERALOGY: OR COLOURED FIGURES INTENDED TO ELUCIDATE THE MINERALOGY OF Btftaftu BY JAMES SOWERBY, F.L.S. HONORARY MEMBER OF THE PHYSICAL SOCIETY OF GOTTINGEN, DESIGNER OF ENGLISH BOTANY, AUTHOR OF ENGLISH FUNGI, ETC. (With Assistance.) As for the Earth, out of it ccmeth Bread, and under it is turned up as it were Fire. The Stones of it are the Places of Sapphires; and it hath Dust of Gold. JOB xxviii. 5, 6. VOL. I. LONDON: PRINTED BY R. TAYLOR AND CO., BLACK-HORSE-COURT, FLEET-STREET; And sold by the Author, J. SOWERBY, at No. 2, Mead Place, Lambeth; and by WHITE, Fleet -street; SYMONDS, Pater-noster-row; and all other Booksellers, rat IMS* h V.I TO THE RIGHT HONOURABLE SIR JOSEPH BANKS, BART., K. B., P. R. S., H. M. L. S., P. R. I., ETC., as the grand Promoter of every Science connected with Natural History, especially Agriculture, to which the Study of Mineralogy forms so necessary an Appen- dage, I, with gratitude for his kindness, a second time dedicate my labours. That they may be useful, is the sincere wish of His most obedient humble Servant, JAMES SOJFERBY. Mead Place, Lambeth, Dec. I, 1804. PREFACE. XHE utility of such a work as this cannot, we pre- sume, be doubted, while the sciences of Botany and Agriculture are so liberally encouraged. We are happy to boast the friendly assistance of men of the first abilities, whose encouragement cannot but be an honour to us. The undertaking was begun at a time when we had but just become aware how far we were behindhand in this most essential knowledge, when even the Diamond, one of the oldest jewels in the known world, had but recently been discovered to be pure Carbon*. Discoveries, scarcely less remarkable, are continually making. The use of figures to illustrate a subject not gene- rally understood, and which it requires so much study to bring to perfection, will be every day more and more apparent; and we have been flattered by the * See page 106. VI PREFACE. avowal of our scientific friends, that we have in this particular exceeded their expectations. A prospectus of this work, so new in its nature, and necessarily capable of many improvements as it goes on, seemed to us better omitted. We had rather perfonn more instead of less than might have been promised. Of the many systems proposed by the learned, not one has been fully established. We have presumed to form one in a general way, for the present pur- pose of arranging the plates and letter-press, feeling the greater confidence in the chance of its permanence, as we have endeavoured to make it conformable to nature. We have made combustible genera, among which are included Calor or matter of heat, the dif- ferent Airs, Alkalies and their compounds, as ne- cessary to be known to every mineralogist, although some are perhaps not strictly minerals. These, with the Earths and Metals, make the three Grand- Divisions or Classes under which we arrange the whole into Orders, Genera, and Species, the Genera chiefly from their specific gravity. For further particu- lars, we refer to the Observations on the System. PREFACE. Vll With regard to the figures, we have thought it quite proper to represent an original specimen, which is apt to give a more perfect idea than geometrical out- lines alone j but, to make them more perfectly un- derstood, have annexed magnified and geometrical figures, as thinking them more valuable for being original; as copies of works, however good, are surely not to be preferred ; especially as, by seeing what is done before us, we are able to manage the subject better, seeing more properly how to show it in a better position, or correct the mistakes. Very common subjects will be included, as they are often more essential to the farmer, builder, mecha- nic, etc., and are generally least known to minera- logists : indeed, we mean to leave no stone unturned, to make the work as universally useful as possible. We beg our friends to accept our grateful thanks for the assistance we have received in this arduous un- dertaking, promising them to be ever attentive to their kindnesses, as a work of this universality requires many helping hands. TO THE RIGHT HONOURABLE SIR JOSEPH BANKS, BART., K. B., P. R. S., H. M. L. S., P. R. I., ETC., as the grand Promoter of every Science connected with Natural History, especially Agriculture, to which the Study of Mineralogy forms so necessary an Appen- dage , 7, with gratitude for his kindness, a second time dedicate my labours. That they may be useful, is the sincere wish of His most obedient humble Servant, JAMES SOWERBY. Mead Place, Lambeth, Dec. l, 1804, PREFACE. tti HE utility of such a work as this cannot, we pre- sume, be doubted, while the sciences of Botany and Agriculture are so liberally encouraged. We are happy to boast the friendly assistance of men of the first abilities, whose encouragement cannot but be an honour to us. The undertaking was begun at a time when we had but just become aware how far we were behindhand in this most essential knowledge, when even the Diamond, one of the oldest jewels in the known world, had but recently been discovered to be pure Carbon*. Discoveries, scarcely less remarkable, are continually making. The use of figures to illustrate a subject not gene- rally understood, and which it requires so much study to bring to perfection, will be every day more and more apparent 5 and we have been flattered by the * See page 1O6. VI PREFACE. avowal of our scientific friends, that we have in this particular exceeded their expectations. A prospectus of this work, so new in its nature, and necessarily capable of many improvements as it goes on, seemed to us better omitted. We had rather perform . - . t r-*n more instead of less than might have been promised. las (Bsiofl lo esairaba 5>rfj Qtidvr .tadaob ad paw?. Of the many systems proposed by the learned, not one has been fully established. We have presumed to form one in a general way, for the present pur. pose of arranging the plates and letter-press, feeling the greater confidence in the chance of its permanence, as we have endeavoured to make it conformable to nature. We have made combustible genera, among which are included Calor or matter of heat, the dif- ferent Airs, Alkalies and their compounds, as ne- cessary to be known to every mineralogist, although some are perhaps not strictly minerals. These, with the Earths and Metals, make the three Grand- Divisions or Classes under which we arrange the whole into Orders, Genera, and Species, the Genera chiefly from their specific gravity. For further particu- lars, we refer to the Observations on the System. PREFACE. Vll With regard to the figures, we have thought it quite proper to represent an original specimen, which is apt to give a more perfect idea than geometrical out- lines alone; but, to make them more perfectly un- derstood, have annexed magnified and geometrical figures, as thinking them more valuable for being original; as copies of works, however good, are surely not to be preferred ; especially as, by seeing what is done before us, we are able to manage the subject better, seeing more properly how to show it in a better position, or correct the mistakes. Very common subjects will be included, as they are often more essential to the farmer, builder, mecha- nic, etc., and are generally least known to minera- logists : indeed, we mean to leave no stone unturned, to make the work as universally useful as possible. We beg our friends to accept our grateful thanks for the assistance we have received in this arduous un- dertaking, promising them to be ever attentive to their kindnesses, as a work of this universality requires many helping hands. 'i r : TAB. I. CALX nativa. Native Lime. Class 2. Earth*. Order 1. Homogeneous. Bab. Gen. 1. Lime. Spec. 1. Calx, nativa. GEN. CHAR. Powdery or concrete, with a ho*t burning taste. Corrodes animal substances. Spec. grav. 2*3, Kirwan, v. i. 5. Precipitates from a solution in water, by adding corrosive sublimate, in the form of a reddish powder. Kir. v. i. 75. Changes syrup of violets green. SPEC. CHAR. Uncombined. SYN. Native lime. Kir. v. i. 74, 75. Pure lime. Bab. 7. Artificial. Calx viva. Mat. Med. V UI CK-LIME, or Calx viva, is well known, as procured from chalk or lime-stone by means of burning in lime- kilns. In the act of burning it is deprived of an air or gas, chemically termed carbonic acid gasf, loses part of its * Earths are incombustible, infusible per se, spec. grav. not ex- ceeding 4-9, and white. t Formerly termed fixed air, discovered by Dr. Black. It is heavier than common air, forming a small or adventitious part of the atmo- sphere ; is readily absorbed by cold -water, giving it a brisk taste. As an acid, it turns vegetable blues red. 2 weight, and takes up caloric, or latent heat of Dr. Black. It is then caustic, with the properties as described in the generic character, changing the syrup of violets green. This character it retains as long as the latent heat or the effect of it lasts, which heat and principle of changing the syrup of violets green will be lost if exposed to a damp atmosphere. The upper figure is done to express artificial lime just ex- posed to damp air, yet capable of changing the syrup of violets green, and beginning to fall to pieces. If a quantity is suddenly added, it will lose its characteristic property sooner, by absorbing carbonic acid gas from the atmosphere, or the water of which the fire had deprived it in the kiln, and when dried without heat will be nearly what it was at -first. The middle figure, Calx nativa, from Bath, has qualities resembling quick-lime, and changes syrup of violets to a green, nearly as vivid as that produced by the artificial lime above ; and although I have had it two years in the drawer with quick-lime, it still gives a green which the other does not. The lower figure represents lime taken out of a hollow nodule of flint, to which, before it was broken, we could find no apparent aperture. The contents were exposed im- mediately to some fresh violet petals, pressed so as to afford two or three drops of purple fluid, which it directly changed green. It soon lost that property, and is now a gritty chalk. External Character of the Bath Lime. Colour white. Lustre o. Transparency o. Fracture earthy. Hardness, rubs easily to powder. It should seem that this passes out of the rocks in a fer- mentative manner, oozing or frothing. The upper surface of the specimen is somewhat encrusted with a stalactitical substance. The inner part when examined seems partly iu bubbles. Dr. Moreton found lime in the stones of Cliftone pit in Northumberland*, and Dr. Falconer at Bath. Sir John Hill describes a similar substance to mine, which he has seen thrown out of the quarries of Mr. Allen near Bath, and calls it native lime and Gypsum Tympbacium of the antients, saying that Theophrastus has left a record of a ship taking fire from the heating of the gypsum among some clothes that were in it, on the accidental admission of wet; and that he does not call it gypsum himself, but an earth only that the people about Tymphaea, &c. called gypsum. * Since the above \va> written, Mr. John Hailstone, Woodwardian Pro- fessor, of Cambridge, kindly informs me that the Calx nativa sent to Dr. Woodward by Dr. Moreton has no pretensions to be a lime. TAB. n. CALX carbonata. Crystallized Carbonate of Lime. Glass 2. Earth. Order 1. Homogeneous. Gen. 1. Lime. Spec. 2. Carbonate of Lime. SPEC. CHAR. Lime with carbonic acid effervesces with the stronger acids, and becomes quick- lime in a strong heat. SYN. Chaux ae'ree. Born, v. I. 28. Kalk-stein. Emmerling, v. i. 437. Aerated or mild calx. Kir. v. i. 75. Chaux carbonatee. Hauy,viiii them. TAB. III. CALX carbonata primitiva. Primitive crystallized Carbonate of Lime, Class 2. Earth. Order 1. Homogeneous. Gen. l.Lime. . Spec. 2. Carbonate of Lime. Div. 1. Crystallized* SYN. Chaux carbonatee primitive. Hatiy,v. 1. 132, 7/>/>. 3. 86. ALBION cliffs, famed of old, are the chalk-hills of Dover in Kent, and chalk is sufficiently known to abound in many parts of Britain. There is no chalk in Cornwall*. Chalk is understood to he a precipitation of carbonate of lime, holding a little clay and sonje flinty particles. It is often in very thick strata, frequently under sand. Flints in strata and of irregular forms are very common in it, and sometimes flints full of flaws, as if mouldering to pieces. Thestratum is mostly horizontal, but sometimes otherwise, 'as at the Isle of Wightf. Many remains of animal exuviae are found in chalk, as shells, echini, corals, &c. and with the rhombic frac- ture: sometimes the echinites are filled with perfect flints. * Dr. Maton's Tour to the Western Counties, t Sir H. C. Englefield in Linn. Trans, r, 6. 16 Martial pyrites, or sulfure of iron, is not uncommon in it, either in full metallic splendor, or in different stales of decom- position passing into ochre or oxid of iron. It is remarkable that Mr. Kirwan, in his Geological Essays, p. 238, says that metallic substances are hever found in chalk. Werner Kal. Classif. 19. Berg. Kal. 233. Yet in France martial pyrites are said to be found in it, 39 Roz, 358 ; as if it were not found in England. Pyrites are found in the chalk of Sussex j I have found them from Dover to Margate ; at Godstone also in great abundance, where the chalk in various ways passes into fine-grained micaceous lime-stone called fire-stone, brought in abundance from Ryegate. The upper figure is nieant to represent a lump of chalk from Sussex, which has a conical fracture hot uncommon in chalk, and sometimes in flint. The little granulae of fine gravel so regularly formed about it, seem to be a filtration of water carrying sand with it through some loose chalk, which meet- ing with a more compact piece runs down the sides in drops, and at the same time is absorbed by the chalk, leaving the sand on the surface in little globules. There are sometimes large quantities of sand in the chalk which fall in occasion- ally, and are called by the Workmen sand gulls. Middle figure. Chalk passing into lime-stone, hardening with inosculating veins. The lower figure represents a piece of chalk rounded by rolling about in the sea, perforated by the Mytilus rugosus, or some species of Pbolas : being stained it loses the appear- ance of chalk. Harder substances are often perforated by testaceous animals. Bryum calcareum, English Botany, t. 191, should seem to indicate good chalk, as I have found the best where it grows. TAB. VIII. C A L X pctrosa Lime Stone. Class 2. Earth. Order 1. Homogeneous. Gen. 1 . Lime. Spec. 1 . Carbonate of Lime. Div. 3. Amorpli illOUS. SYN. Pierre a chaux commune. Born, v. i. 284. Kalxstein. Emmerling, v. I. 437. Compact limestone. Kir. e u. i. 82. Chaux carbonatee grossiere. Hauy, v. 2. 166. LIMESTONE, generally speaking, is carbonate of lime, harder than chalk, often containing 10 or 12 per cent, of clay or iron. If so much as 15, Mr. Kirwan says it should be excluded, as scarcely affording good lime in burning. Upper figure. Ketton-stonc, found in abundance at Ketton in Rutlandshire. It is remarkable for its singular ac- cretions in the form of fishes roe, whence it is often called 18 Roe-stone. It is used for building in many places: some of the colleges at Cambridge are built with it. The same uniform appearance extends to very large masses ; and al- though a sound, strong and durable stone in the mass, very little pieces may be crumbled to grains by the ringers. The masons use a common carpenters saw in working it : the little rounded particles being easily detached, it passes readily through it. They sometimes have a little dusty or solid nucleus, coated concentrically; at other times are hollow. In the next county, Northamptonshire, there is a stone called by the masons Barneck, greatly resembling this, but coarser, containing shells, &c. Col. Walford found a stone of a similar nature with larger grains (which approaches the oviform limeftone of Kirwan, v. i. 91), atBirdbrook, Essex, mingled with shells, which has sometimes sufficient clay or argil to be called a marie. Middle fgure. Bath-stone, frequently contains the same concretions, but more decomposed, and a matrix surround- ing them, somewhat confusedly crystallized, forming little hollows : many species of shells, encrini, &c. are found in it ; sometimes however so comminuted as to be quite indistinct. I picked up a piece of stone at Burford in Oxfordshire, which is of a reddish brick colour, with the hollows very distinct, giving it a volcanic or cindery appear- ance. With difficulty very small pieces crumble between the fingers. Lower jigurt. Portland-stone, nearly like the Bath-stone. The best sort is more compact, and whiter : there are many 19 arieties of it, pafling into marly, flinty, &c. It often affords good crystals. The specimen figured had some little rhombs half relieved on it. A crystallization called, from its resemblance, sugar-candy spar is frequent among it. Shells of various kinds are often found in it. Sometimes it appears in the form of large trunks of trees, hardest with- in, resembling whitish chert. Ketton- stone, colour light reddifh brown, lustre o. Transparency o. Fracture earthy granular. Hardness 5 or 6. It contains 90 per cent, calx, and 10 of argil. The Bath and Portland nearly the same in most respects, but harder. Spec. grav. Ketton 3'45<5^ Bath 2-494 > Kir. v. i. 88. Portland 2'46iJ TAB. IX. CALX coralliformis. Coral-form Carbonate of Lime. Class 2. Earth. Order 1. Homogeneous. Gen. 1 . Lime. Spec. 2. Carbonate of Lime. Div. 2. Imitative. Ellis corallines, p. 76. /. /W*W *, , /. TAB. XJI. CALX carbonata, var. equiaxi-lenticularis. Crystallized Carbonate of Lime, lenticular- equiaxed. Class 2,. Earth. Order 1. Homogeneous. Gen. 2. Lime. Spec. 1. Carbonate of Lime. Div, 1. Crystallized. Var. 1. Equiaxed. -i HE figuring of this shell will not only serve a geological purpose, and show a curious crystallization, but help to explain the flattened crystals in the next plate, which are not easily understood, as the lines they form in the draw- ing give but little idea of flatness, and may seem to express the perspective of a cube, especially as we are not yet much accustomed to these representations. This is the Hehnintholitbus Ammonites of Linn. Gmel. V. 3. 411. usually called Cornu-ammonis, of which there are many species found in the petrified state*, abundant in * This species and many others are found on'y in this state, never recent. 30 many parts of Gteat Britain. Abroad they are often siliceous, or at least contain siliceous crystallizations ; but in Great Britain are mostly calcareous, found in lime-stone rocks and marly places. The shelly part may some of it be the remains of organic structure. The crystallized internal parts of shells and stones afford a curious subject for in- quiry. In the chambers of this nautilus, (for so the living genus is called by Linnaeus, see Gmel. v. i. 3369., the matter of crystallization may have passed through the alveolus, or little hole, fto each partition. In other shells, and in geodes, it must be otherwise. The crystals are rough, and in nearly a regular series from the primitive to the equiaxe. The faces howevej of the latter are rounded, giving it a lenticular form . They are also somewhat striated, resembling the lenticular crystals of certain spathose iron ores. TAB. XIII. CALX carbonata var. aequiaxis. Crystallized Carbonate of Lime, var. equiaxed. Class 2. Earth. Order I. Homogeneous. Gen. 1. Lime. Spec. 2. Carbonate of Lime. Div.l. Crystallized. Far. 1. Crystal Equiaxed. B SYN. Chaux carbonatee equiaxe. i. Haiiy, -u. 2. 132. g , M ,,, THIS crystal is formed of six rhomboidal faces the angles of which are 114 i8'56 /; , and 65 41' 4", forming a very . obtuse rhomb, the axis of which is equal to that of the rhomb which it encloses. Haily, v. I. 133. These and their modifications are found plentifully in Durham and Cumberland, according to specimens sent me by the Rev. Mr. Harriman and Mr. Oliver. I have "had fine specimens from Newcastle by favour of Mr. Wood- house, found in coal mines. They occasionally occur wherever other calcareous substances are found. The upper figure is part of a fine specimen with clearer crystals than usual, for they generally incline to a milky hue. They frequently stand on their edges, or are as it were thrown about in different directions, on various matrices. This is on dark or gray lime-stone, with blend* and galaenaf. The first is confusedly crystallized, which commonly happens ; the latter more regularly so, in cubes with the- corners truncated, or a cubo-octaedron, as Haiiy rightly terms it. The lower figure has smaller crystals, roughish towards the edges, as if not quite finished. The roughness proceeds from the edges of the molecule, or from spaces where there seems something wanted to finish the faces and make the surfaces even. The crystals are somewhat striated towards the centre, and are loosely fixed among light purple fluor and galaena. * An ore of zinc called by the miners black jac!-:. t An ore of lead. TAB XIV fr.v js ^ni?^ : >\> .v A R G I L L A Marga. Argillaceous Marie. tJLii vlib.. };;.. ,: . ** :ibA*9flS \09tM Class 1. Earth. Ord. 2. Mixed. Gjb to 7.331. Smell unpleasant. Fuses at 410* Fahrenh. Not soluble in nitric acid. SPEC. CHAR. Tin united with oxygen. SYN. Common tin stone. Kir. v. 2. 197. Zinnstein. Emmefling, v. 2. 421. Etain oxyde. Haiiy, v. 4. 137. Stannum crystallinum. Linn. Syst. ed. 12, v. 3. 130. TIN, although universally known in the metallic state as obtained from its ore, would never be recognizable without experience in the crystallized oxide, from which it is chiefly procured. This crystal was once though t, by the Cornish miners, to be destitute of metal. The tin mines of Corn- wall are the most famous in the world, and were very early known. The Phoenicians procured this metal from thence. The Cornish tin ores are said to be the most pure, as they contain less iron and arsenic than those of Bohemia, Saxony, &c. The crystals are mostly confused : specimens however are sometimes found (and preserved to gratify the curious) which are very distinct and beautiful. They resemble bottle glass ; are mostly of a black hue, approaching a brownish horny lustre ; sometimes brighter, and with a fiery sparkling, varying to red, gray, or whitish. The crystals are the cubic or octaedral modifications: the perfect cube has never, I believe, been found. The octaedron, I am told, is perfect in the Honourable Mr. Greville's collection. I have one nearly so. They often press against each other, forming macles, &c. This ore is found varying, sometimes amorphous, in the quartzose, decayed granite, or growan, killas, and other rocks : also in streams, and is then called stream tin. It occurs also in pebbles, and sandy particles. A rare species, called wood tin, or tin haematites ; also an- other called tooth tin, and sulphuret of tin, are found in different parts of Cornwall. There is very little tin in Devon- shire, and none in any other county of Great Britain. - , ' T ! A T^ XTX ; Oa \mcxk; oi'" CALX carbonata, t?ar. margaritacca. Pearl Spar. i^H Class 2,. Earth. Orrf. 1. Homogeneous. Ge. 1. Lime. Spec. 2. Carbonate of lime. Div. 1 . Crystallized, crystal primitive. Par. With some iron and manganese. Lustre pearly; crystals often curving. 88 , SYN. Sparry iron ore. Kir. v. 2. 190. Spathiger eisen stein. Emmerl. v. 2. 329. Werner. Chaux carbonatee ferifere. Hauy, v. 2. 175. Pearl spar. Bab. 18.' HAVING so distinguished an appearance from other car- bonates of lime, this has obtained the name of pearl spar, a name it naturally suggests, and by which it is in general easily recognized. We find however, like other subjects in nature, it has its gradations, and consequently blends itself with substances to which at first it seems very little allied. It maybe readily traced, as formed from the primitive crystal of carbonate of lime, to an iron ore, consisting for the greater part of oxide of iron, and manganese. The progress, if I may so call it, appears curiously and distinctly marked by the manner of the crystals, which are in the forms of the primitive rhombs, and are white: sometimes however it approaches the appearance of ivory ; and as its substance becomes pearly, the nuclei seem to be separating and curv- ing from about the angle of 30 to about 20; see the figures. They mostly appear of the natural pearly lustre, but are often at length more curled and darkened, and thence may be called spathose iron ores : perhaps they may be called iron ores whenever the common browner aspect seems to indicate as much. Those, however, which have the forms and fracture of crystallized carbonate of lime may be placed as such while they retain the whitish pearly lustre. Pearl spar analysed by Bergman contains Lime 38 Oxide of iron 38 Oxide of manganese 24 100 By Wolf, Ai .'itvft .iijqg h;.i/f Carbonate of lime 60 Oxide of manganese 35 Iron 5 100 By Berthollet, Carbonate of lime 96 Oxide of iron and manganese . . 4 100 Thus different analyses, showing a difference in the pro- portion of the substances of which it is composed, decide it to be more or less an iron ore. 'l IMJAMfiaf b J*' St ~ trt S TAB XX CALX carbonata primitiva, var. Pj'imitive Carbonate of Lime, var. Class 2. Earth. Ord. 1. Homogeneous. Gen. 1 . Lime. Spec. 2. Carbonate of lime. Far. Crystal primitive, with secondary faces parallel to both those of the equiaxed and metastatic. THIS curious crystal is sometimes found at Castle-Town in Derbyshire. Its gangue is generally a bituminous limestone. It is a little milky On the outside, and roughish ; those edges excepted which are rounded : see the left-hand figure. The right-hand figure has broad faces leading to the equiaxed crystal, which faces are as it were polished, and in the mid- dle is a longitudinal line showing the edge of the nucleus, consequently the laminae of superposition : see the upper part of the right-hand figure. There are also rough faces leading towards the metastatic crystal : see the lower part of the right-hand figure. As I had but indifferent specimens myself, I borrowed the specimen here figured of Mr. Richard Phillips, thinking it well worth noticing. The little black spots are drops of mineral pitch, which mostly accompany these varieties. They have generally been termed primitive crystals, without further consideration. In an arranged col- lection they may be placed near to the primitive. TAB. XXI, Upper Figure. CALX sulphurata; var. plumosa. Sulphate of Lime; var. plumose. Class 2. Earth. Ord. I . Homogeneous. Gen. 1. Lime. Spec. 5. Sulphate of lime. Div. 2. Imitative j var. plumose. SYN. Sulphate of lime forming snow-white incrusta- tion, &c. Bab. 29. ccxvi, a, 1. Chaux sulfatee niveforme*. Hauy , 2. 279, THE -upper Jigure is a curious variety of sulphate of lime, or gypsum, from Matlock. It should seem that sulphur of iron or pyrites, by exposure to damp, decomposes ; the sul- phur combining with oxygen forms sulphuric acid, which comes in contact with the lime in the rock, and so forming gypsum, oozes out in these fanciful forms; or, in other words, readily produces gypsum more or less crystallized. It is continually forming in many parts of England, Lord Altainont obligingly sent me some nodules of pyrites, in * A yariety found at Montmartrc. 50 which gypsum is formed, from a well just dug in Cambridge. It is continually crystallizing from the sulphur of pyrites and oyster shells at Shotover Hill, near Oxford. The lower figure is on a piece of limestone with a foetid odour, called stinkstone, the gypsum spreading in a very peculiar manner on the surfaces in patches. I was favoured with this from the neighbourhood of Durham, by the Rev. John Harriman, TAB. XXII, Upper and Middle Figure, SODA muriata. Muriate of Soda, or Common Salt. Class 1. Inflammables. Ord. 2. Mixed. Gen. 4. Soda. Spec. 2. Muriate of Soda. Dlv. 1. Crystallized. GEN. CHAR. Soda in combination. SPEC. CHAR. Soda combined with muriatic acid. SYN. Common salt. Kirw. v. 2. 31. Common salt, sea salt. Rab. 14. Stein satz. EmmerL r. 2. 19. Soude muriatee. Hamj^ v. 2. 356. Muria montana. Linn. Syst. ed^ 12. i>. 3. 98. FOUND in abundance at Northwich in Cheshire, where it constitutes von- solid strata, more or less mixed with common clay, giving it a dirty hue, or with yellowish or red calx of iron. Its large square crystals are often so transparent and clean as to appear uncontaminated. The miners leave pillars of it to support the roof; and when they show this grotto, they are proud to surprise the spectators, and add lustre to the scene by the display of many lights, The middle Jigure shows the fracture to be cubic, and also pome clear pieces lying among the coloured kind. I have none approaching the octaedron or the cubico-octaedron, eee Haiiy ; nor do I know that it is found so in Great Britain. Salt in sufficient quantity preserves animal substances from putrefaction, but too little is said to promote it. Lustre 2 or 3, glassy. Transparency 2, 3, or 4. Hardness 4, 5, or 8. Spec. grav. 2,143. Brisson. Soluble in little less than 3 times its weight of water, at the temperature oj 52 60. Kirw. Refraction single. Salt in the artificial way of pre- paring it, if crystallized hastily for use, has the centres of the cubes concave, or depressed, as it were, step by step from the edges, forming a curious figure. This is not un- common in what is called rock salt, which is often brought to our tables in preference to basket salt ; so called from being sold in fine grains, and pressed into conical baskets. Com- mon salt is also used for glazing common earthen ware. 100 parts of this salt contain 35 of soda, and nearly 40 of muriatic acid, the rest being water. Kirw. 2. 33. Soda is an ingredient best procured from common salt. It is otherwise procured from sea plants. Soda not being found native in Great Britain, I take occasion to speak of it in this place. It is useful in making glass, and has lately been much used in common washing ; often indeed so indiscreetly as to rot the linen, and even to act as Hercules's poisoned shirt, particu- larly to the tender skin of infants. Mothers will do well to be assured of their linen being well rinsed in plenty of cold water. TAB, XXII, Lower Figure. SODA fibrosa. Fibrous Muriate of Soda. Dly. 2. Imitative. FIBROUS salt may be found of different shades of white, red, or brown, depending either on common clay, or on oxide of iron. This specimen has a piece or two of common clay in the centre. Its fibrous part is coloured by a red oxide of iron. This sort of specimen lias been compared to wood, the curvature of the fibres and the fracture corresponding to that fanciful idea. Some have thought the- red kind here figured resembled muscular fibre*. TAB. XXIII. FERRUM sulphuratum. Sulphate, of Iron. Class 3. Metals. Ord. 1. Homogeneous. Gen. 7. Iron. Spec. 6. Sulphate of Iron. Div. 1. Crystallized, SPEC. CHAR. Sulphuric acid combined with iron. SYN. Vitriol martial. De Lisle, v. 1. 331. Sulfate de fer. De Born, v. 2. 39. Vitriol vert. Daubenton, 28. Vitriol of iron. Kinv. v. 2. 20. Fer sulfate. Haiti/ , v. 4. 122. Vitriolum martis. Linn. Sy&t. ed. 12. v. 3. 104. (j KEEN vitriol, as it is commonly called, is found crystal- lized, stalactitical, or in amorphous lumps, in many parts of Great Britain. The present is a curious specimen from Hawkshead coal mine, near Glasgow. It appears by a note sent to Mr. Vansittart with this and some other specimens winch I had the pleasure of receiving from the Rev, Dr. Beeke, that the mine had been worked for above 200 years, from the crop to the dip (as the colliers term it), that is, following the descent from where it appeared on the surface, always working at the lowest part. Thus the upper part*, or pits, first worked were necessarily kept free iron; 54 and were left exposed to the external air above the coal stratum. The black clay, or aluminous ore, being the deling of the mint, absorbed the Oxygen in the common air by means of the sulphurc of iron, (which is almost imper- ceptibly mixed with it,) in such abundance as to expand it, first in the form of white silky threads, merely separating the laminae in a somewhat undulating form, but afterwards expanding it in such a manner, that the whole stratum, which was but 14 inches, sometimes became a yard in thickness falling to the floor; and the threads, from being scarcely percuptible, become near an inch long, curling in many fanciful directions*. It sometimes ripens or consoli- dates into what the workmen call native copperas, and may possibly hold a little copper. It is somewhat crystallized, like the green part figured, upon the clay or aluminc, which is in the act of throwing out little white opaque round spots, the effect of a further change since the speci- men was in my possession. These probably contain less water than the other parts. Its transparency is 2 or 3. Kirw. This is a very good alum ore, the sulphuric acid and the argil being by proper means separated, and recombined to form that substance. * Which will be shown in Plate xxviii. 56 is said to be owing to their containing more silver. Some varieties have a diverging striated fracture. This ore holds lead in the metallic state. Before the blowpipe on charcoal it decrepitates, but melts easily with a sulphureous smell, part sinking into the charcoal. If alternately heated and cooled, it will at last vanish, and leave its silver, if it contains any. Berg. 493. Spec, grav. 7,587. Brisson. Viv:- -'.'-"' " ' ' ' 1.T'- , TAB. XXV, --':.- . . CUPRUM nativum ; var. arborescens. Native Copper ; var. arborescent. Class 3. Metals. Ord. 1. Homogeneous. Gen. 7. Copper. Spec. 1. Native Copper. Div. 1. Crystallized. SYN. Kinv. v.2. 128. Haiiy, v. 3. 521, ARBORESCENT copper differs from the dendritical, (which branches chiefly from its sides, and is mostly compressed,) in branching many ways without compression, and in gene- ral being more perfect in crystallization, as it is formed among loose fragments of quartz> The crystals are 1 2-sided,, and sometimes large enough to be easily seen without a lens ; at others many are accumulated and attached to each other in different directions, forming the appearance of a rough stem and leaves. They often widen and form macles. The colour and lustre vary from light and bright yellowish- red to bright brown-red. The lower figure I bought in Truro, and understood that it came from a mine in that vicinity. The upper figure is rather between dendritical and arborescent copper, but the definition is of no re.nl con so quence. The crystallizations are less perfect, and are made still less so by the green oxide covering the surface, and giving it a more vegetable-Hke appearance, except that its colour is too gay for any vegetable we know. It comes from Huel Jewel in Cornwall. TAB. XXVI. f-j- -. wd\r; CALX Fluor primitiva. Primitive crystallized Fluate of Lime; or Fluor*. Class 1 }. Earth, Ord. 1. Homogeneous. Gen. 1. Lime. Spec. 3. Fluate of Lime. Div. 1. Crystallized. SYN. Chaux fiuatee primitive. De Lisle, t. 2. p. 15* Haul/, v. 2. 249. t. 31. /. 74. Rashleigh, v. 1. t. 24. f. 1. OCTAEDRAL fluor is rare, as I have observed at t. xi of this work. The upper figure of the present plate is from a spe- cimen given me by the Right Honourable Charles Greville. It is found at Beer Alston, in Devonshire. I have never seen any of an opaque white but from thence ; and, which is an addition to the curiosity of the specimen, the crystals here are alternately opaque white and transparent green, being as it were cased upon one another, 5, 6, or more times. The transparent kind gives the usual vivid glow when laid upon a hot poker, soon crackling and flying away. The white part does neither, and will remain as a defence to the next transparent part, until a stronger heat bursts it. The matrix is commonly hornstone in apparently broad strata, next to a sandy one on the side opposite to the fiuor j with considerable hollows, seemingly the impressions '" Perhaps it is merely a carbonate of iiine only. 60 of some large confused crystallization that had been in the next strata. This hornstone, from specimens given me by Lord Heathfield, has sometimes apparently very large green octaedral fluor on it, covered with quartz crystals, and some varieties of octaedral pyrites. The irregular fracture of the former gives the matrix an odd appearance, some- what resembling the ground plan of a fortification, and not unlike what is called fortification agate, found on the Scot- tish coast. The figure at the top of the plate shows the octaedron and its cases. The lower Jlgure is octaedral fluor, from Aberdeenshire. I believe this may be the first time it has been noticed*. They are of a dark purple, but do not detach so freely as the above : they arc lighter purple or greenish on the inside, and are heaped confusedly in a stratum of calcareous spar and cawk, if I am not deceived. The figures at the bottom are octaedrons lying on one of the faces, to show that the fracture which is parallel to the face gives a hexangular form, a? expressed at the left-hand figure, and will account for the hcxacdfal remains of the crystal in the figure. The more triangular fractures are nearer the primitive faces. Jnint.ors does nr* observe nny thirty more than that fluor has been round in Ahcrdctrshirc. I think if he- liad seen any ocucdrons he would have s\iil so. \{ 7 ' ' '.../.* TAB. XXVII. CALX Fluor primitiva. Primitive crystallized Fluate of Lime, Vr'i ;,.' , Class 2. Earth, Ord. 1 , Homogeneous. Gen r 1. Lime. Spec. 4. Fluate of Lime. Dlv. 1. Crystallized. SYN Rashleigh, 1. tab. 24. / 2. THE upper jigure here represented seems very nearly allied to the green fluor in the hornstone mentioned at tab. 26. Mr. Rashleigh's, which must by the figure have been a very fine specimen, was elegantly formed among long columns of quartz, and came from the Pell mine, St. Agnes, Corn- wall, where I understand my own was found. It is a rarity, as Mr. Rashleigh observes, and I am therefore happy to re- present it here. It has no matrix, and appears to have been joined to a larger mass of its own substance, the fragment? of which remain with it, and serve to show that the ruder parts have a tendency to the octaedral figure. A remarkable circumstance belonging to this and the green part of the fluor, from Beer Alston, is : that on the hot poker it gives a blue green glow nearly like itself, but lighter from its brightness and somewhat more blue, very nearly resembling the chlorophane of Siberia mentioned at tab. xi. The lower representations are designed to show the nature of the crystallization, which at first appears as if it had a rec- tangular octaedron for the primitive and integrant molecule : but on examining the fracture carefully, we find signs of many forms, and can produce fragments truly tetraedral and rhomboidal ; the former of which assists to form the octaedral ; and (vice versa) one octaedron with four tetra- edrons forms a tetraedron placed as in the right-hand figure. An octaedron requires 6 octaedrons and 8 tetraedrons to form it, as in the lowest figure. The rhomb, which might be taken for the primitive, is composed of one octaedron and two tetraedrons, as in the left-hand figure, &n octa- edron is tinted in each to make it more apparent, and the lowest figure has also a tetraedron coloured. The fracture in fluor is very distinct from that of carbonate of Jime, and is parallel .to the faces of the octaedron, each plate having always one hcxangular face, sometimes 2, forming altogether a flat octaedron, like the bottom half of the left-hand figure in plate xxvi. Perhaps fluor fractures 01 1 iit:> more natural varieties of figures than any other minu;J substance. However, as the octaedron is always to be found in it, and is included most simply in the tetraedron, the latter may be called the integrant molecule, and the former the primitive crystal. I do not know that the tetraedron or rhomb has ever been obtained, except by means of frac- ture. TAB. XXVIII. FERRUM suiplmratum. Silky filamentous Sulphate of Iron. Class 3. Metals. Order I. Homogeneous. Gen. 7. Iron. Spec. 6. Sulphate of Iron, Div. 2. Imitative. Far. White Silky. 1 AB. 23 shows the beginning of this white silky substance^ by means of common moist air decomposing the pyrites, which is held in the black clay in such abundance in this specimen, as to separate and divide it so confusedly, that it is only recognizable by the little thin flakes, which still give out small floccose particles if in a damp place. The green crystallized parts in this specimen are also forming into white woolly fibres. Whitby, in Yorkshire, has of old been famous for alum works, as have other parts of the sajue county. My kind friend the Rev. James Dalton was so good as to send me specimens of alum ore from Mr. Baker's Boulby works. It is a more compact ore than that from Glasgow. Dr. Travis, of Scarboro', gave me some from Skowbrow, among which a baked specimen has some of the silky filaments remaining, as in Tab. 23. Alum has not been discovered native in England. It is said to be found abroad in octaedral crystals, which is the form of the artificial ones. Of these I have a most superb speci- men, sent by the Rev. James -Dalton, from Mr. Baker's alum works above mentioned; also some beautiful little crystals formed by agitation in a wine-glass, showing the lesser octaedrons within the larger, and some curious mo- difications. The crvstallized specimen from Scotland has a prism. TAB. XXIX. FERRUM sulphureum. Sulphuret of Iron. Pyrites. Class 3. Metals. Order I. Homogeneous. Gen. 7. Iron. Spec. 5. Sulphuret of Iron. Div. 1. Crystallized. SYN. Martial pyrites. Kirw. v. 2. 76. Pyrites martiales. Marcassites. De Lisle, v. 3. 208. Schwefel kies. Emmerl. v. 2. 289. Fer sulfure. Haiiy, v. 4. 65. THE upper figure is from Cornwall. This substance is very universal, and not rarely occurs crystallized. It is perhaps as often found in the cubic or primitive form as any thing we know of, especially among the schistose rocks in Wales, Scotland, Cornwall, and Ire- land, on what Dr. Babington denominates Calp, vulgarly called Irish Diamonds. This sort was used formerly for making buttons, and was in fashion as jewellery for ladies' ornaments about half a century ago, being cut and polished by the lapidaries for that purpose, often to the destruction of the natural crystal. It is often found among coals, &.c. 68 ft forms many varieties of crystallizations. T/ie tipper Jlgitre shows a group of cubes : the larger one appears some- what laminated in the structure, and is nearly covered as it were with a thin case. They are often quite smooth, but are more frequently found with straight lines or striae on the faces, alternating with the faces next to each other, but agreeing with the opposite sides or faces. The cubes are often larger than those here figured. Under the blowpipe the odour of sulphur is very sen- sible, and a.magnetical oxide of iron is to be produced. It scintillates with steel. The lower Jigure from Redruth, in Cornwall, with little cubes, piled like clubs, and somewhat varying in colour, perhaps contains a little more copper. Mr. Kirwan says a small portion of copper is always present in pyrites. The upper part being paler than the lower is a sort of indication of its holding most iron. Spec. Grav. 4,10064,7491. TAB. XXX. FERRUM sulphureuni. Sulphur at of Iron. Pyrites. Class 3. Metals. Order 1. Homogeneous. Gen. 7. Iron. Spec. 5. Sulphuret of Iron. Div. 1. Crystallized. SPEC. CHAR. Sulphur combined with Iron. THESE crystals were communicated by the Rev. H. Davies, from Parys Mine, Anglesea, where there is great abundance in eome places, heaped together like grains of sand, so small that their lustre is lost in their minuteness, much less can the cubic form be seen without a magnifying glass. The rocks of limestone, and those passing to re- gular slate, -contain them of different sizes. The upper Ji-gure is from a specimen the gangue of which is between common limestone and slate, and contains no small quan- tity of the crystals. The gangue is in the more chalky- parts stained a little green, perhaps from some oxide of copper. The lower figure is a piece of undulated (other- wise common blue) slate, which is a durable sort if free from pyrites, as the common air decomposes the pyrites, .decays the iron, and the slate becomes rotten. This will be further explained when we are treating of the best slate of Wales, Westmoreland^ Yorkshire, Cornwall, &c. 4 TAB. XXXI. C U P R U M arseniatum. Arseniate of Copper. Class 3. Metals. Order 1. Homogeneous. Gen. 4. Copper. Spec. Q. Arseniate of Copper. Dw. 1. Crystallized. SPEC. CHAR. Arsenic acid combined with copper. SYN. Philos. Trans, for 1801, p. 169. WE are obliged to Mr. Chenevix and Count Bournon for the best account of the arseniates of copper. They are found at Huel Gorland mine in Cornwall. The simplest variety, according to Count Bournon, is the obtuse octa- edron. He observes that this octaedron has, in each of its pyramids, two opposite planes more inclined than the other two; which gives a parallelogrammic form to their com- mon base. The two planes which are most inclined meet at the apex of each of the pyramids, in an angle of 1 30, and at the common base in one of 50. The two planes which are less inclined meet at the apex in an angle of 115, and at the base in one of 65. The faces are sometimes smooth, mostly bright, and oc- casionally show signs of the angles of the tctraedron, or have striae parallel to their edges, as Count Bournon obr serves. He also remarks that the four planes terminate in one and the same point; but more commonly the apex is formed into a ridge, the octaedron being lengthened pa- rallel to the lesser inclined planes. The base is then a square, or at least approaches nearly to that form. Thejirst figure seems to be rare ; those with the ridge arc more com- mon, particularly such as are further lengthened, passing from the right hand figure in my Plate to the left*. The gangue is an ochraceous quartz with some copper, and often approaches what is called pitch copper: the right hand JigUf$ has a little green globule of a waxy appearance. Such arc sometimes abundantly scattered over the octaedral crystals, and appear to be carbonate of copper, or malachite. It is either of a beautiful dcepish azure blue with a greenish cast, exactly resembling pure Roman vitriol, or artificial sulphate of copper somewhat opaque, or of a fine green ; in which last casc.it resembles the emerald. Such specimens arc most transparent, and vary in being some- times lighter coloured. These are frequently blue within, * The Count mentions thrsc as the only two varieties he has observed in tlie form of the crystals of this species, although he had opportunity of exa- mining a great number of specimens. I am happy to add a new, and I think in-ercstinp, variety, especially as it seems, from what has been said above, to be very rare. See tab. 32. 73 as the fracture readily shows. We shall now consider the present specimens chemically, with the assistance of Mr, Chenevix, who, as well as Count Bournon, remarks the rarity of this substance in any other country ; and it ap- pears that Mr. Haiiy had only seen the hexaedral va- riety of arseniate of copper from Cornwall, in the hands of a friend, when he was about his very ingenious work on crystallography. We therefore may safely conclude that the present and first species of Count Bournon, with all the others, are described in the Philosophical Transactions only, or in works copied from 'thence. Vie shall, however, ex- hibit some varieties not yet described, one of which may be seen in the next plate. That able chemist Mr. Chenevix, having favoured the public with the analysis, found it to contain Oxide of copper 49 Arsenic acid 14 Water 35 98 TAB. XXXII. CUPRUM arseniatum. Arseniate of Copper. Class 3. Metals. Order 1. Homogeneous. Gen. 4. Copper. Spec.g. Arseniate of Copper. Div. i. Crystallized. far. The solid angles of the mutual base of the two pyramids truncated. SPEC. CHAR. Arsenic acid combined with copper. SYN. Phil. Trans, for 1801, p. 169. THIS being, I suppose, a scarce variety, not having been mentioned by the experienced Count Bournon, I am happy to give a figure of it to the public. Among the clusters of grass-green crystals of arseniate of copper, we mostly find some with the corner of the mutual base of the pyramids more or less rounded. These in the present specimen form regular facets, making it a twelve-sided crystal. The facets pass the common base at right angles, cutting off the four corners : thus the mutual base is an octaedral plane, at right angles with the four corners of the double pyramids. They are somewhat uneven, and show evident signs of the want of a few molecules to fill up their interstices. The crystals in general soem to have been disturbed or in- terrupted, and show markings on their surfaces. Besides this, I have a variety with the sides of the mutual base somewhat rounding, though scarcely perceptible, which is figured in ttie left hand outline. The broken crystal in the middle, to show the blue within, was most conspicuously so, and is figured of its natural size, being larger than usual : the other two are slightly magnified. We have since met with one five-eighths of an inch long. TAB. XXXIII. CALX carbonata, var. metastatica. Carbonate of Lime, var. metastatic. Class 2. Earths. Order I. Homogeneous. Gen. 1. Lime. Spec. 2. Carbonate of Lime. Div. 1. Crystallized. Far. Metastatic. SYN. Dent de cochon. De Lisle, tab. 1. p. 530. 2 Chaux carbonatee metastatique. D Hauy, v. 2. / > 134. ^ THIS form or variety of crystallization of carbonate of lime is perhaps one of the most common, and has ob- tained the name of Dog's tooth spar in England, and that of Dent de cochon, or Swine's tooth, in France. This crystallization is prevalent of different sizes, colours, 8cc., in Derbyshire, some affording good examples of the pri- mitive rhomb, being clear, and differing very little from the true Iceland crystal, which is reckoned the most pellucid, and for a figure of which see our tali. 2. The left hand lower figure shows the usual construction, the edges of the opposite pyramids meeting on the edges of the primitive rhomb, when the obtuse ends are opposite to each apex *, the more acute angles forming three principal ones, and the obtuse three less distinct ones : thus each pyramid has six sides, the acute and obtuse meeting in alternate order at the * The metastatic is formed by an addition of laminz, formed of rhom- boidal molecules upon the faces of the primitive rhomb, each plate decreasing io width twice its thickness. This will be more fully explained hereafter. 76 common base. The right hand figure represents two pyra- mids of the same, transversely cut through the middle, showing a plane of 1 2 sides, and turned on the axis till they meet each other in an opposite direction, exhibiting a re- markable appearance, called by some authors macling. They often seem to be two crystals passing into each other, and arc then said to be twins. This is formed on a gangue or lump of manganese, or black wad as the miners term it, which seems to give the crystals a dirty tinge, especially those nearest to it. We do not know that it has any other effect on the crystallization. TAB. XXXIV. C A L X carbonata, rar. inctastatica. Carbonate of Lime, var. wetastatic. Class 2. Earths. Order 1. Homogeneous. Gen. 1 . Lime. Spec. 2. Carbonate of Lime, Div. I. Crystallized. fur. Crystal metastatic terminating with primitive facets. UPPER FIGURES. The metastatic crystallization is form- ed, as before observed, by a particular arrangement of the molecules. These continue to form regularly, according to the supply of those molecnles, which, stopping abruptly, terminate in the obtuse point of the primitive crystal, show- ing three faces. This termination is not very common : the outline on the left hand will help to explain it. The other lateral faces will be spoken of hereafter. The lower Jlgure shows the cquiaxc termination, and the right hand geometrical fgure, its formation upon the rhomb. I " TAB. XXXV. CALX carbonata, var. metastatica. Carbonate of Lime, var. metastatic. Class 2. Earths. Order 1. Homogeneous. Gen, 1. Lime. Spec. 2. Carbonate of lime. Div. 1. Crystallized. Var. Metastatic terminating with equiaxed and other faces. THIS fine yellowish crystal shows at the apex three po- lished faces, which are parts of the equiaxed crystals : se- veral others next to them show the approach to the primi- tive rhomb, and three primitive faces ; the rest is part of an unequal-sided or flattish metastatic. The double re- fraction is seen, when held in certain directions, by the prismatic tints, which are very beautiful, and in some posi- tions catch the rays of light, so as to show them in great abundance in the numerous flaws ; which flaws would be some detriment to the specimen, if this appearance did not so well compensate for them. They also serve by their direction to show how the fragments are obtained which exhibit the nuclei. See tal. 2. TAB. XXXVI. CALX carbonata, var. metastatica. Carbonate of Lime, var. metastatic. Class 2. Earths. Order I. Homogeneous. Gen. i. Lime. Spec. i. Carbonate of Lime. Div. i. Crystallized. Var. Crystal metastatic. THIS specimen shows a variety of faces depending on cer- tain laws of increase and decrease, and seems more regu- larly forming the metastatic within, where it abounds with pyrites, than externally. This serves to show that crystal- lization may continue while one substance has another within it. The pyrites, from their colour, as well as form, should seem to hold copper as well as iron. 'l ltt3 /V.*/,W .. /. ' TAB. XXXVII. CUPRUM arseniatum. Arseniate of Copper. Class 3. Metals. Order 1. Homogeneous. Gen. 4. Copper. Spec. g. Arseniate of Copper. Div. 1. Crystallized. Far. Crystal an hexaedral plate with inclined edges. SYN. Cuivre arseniate lamelliforme. Hauy, v. 3. p. 578. Arseniate of copper in hexaedral laminae, with in- clined sides. Phil. Trans. 1801, p. 176. 1 HIS beautiful variety is described by Count Bournon in the Philosophical Transactions for 1801, and we cannot do better than profit by his description. fc It is in very thin hexaedral laminae, the six sides alternating in an inclined position, with the broad hexaedral planes on either side at an angle of about 135, an4 the third at 115, on the op-, posite side." See fig. 1. The crystals are more or less piled on each other, and are often to be divided, or split parallel to their surfaces, in the same manner as Mica. They are very brittle, mostly of an emerald green, and as transparent as the best glass, their lustre resembling the thin glass called frosting ; or, as the Count expresses it, the lustre of those coloured metal plates known by the name of foil, and are most splendid when the light falls on the broad planes. The' edges are more opaque, partly from the contrary direction of the crystal, and partly from the striae in the direction of the lamina?. Fig. 2. is a general group of crystals. Fig. 3. shows a variety in my possession of a yellower tint *. The lower geometrical jigurcs show , according to Count Bournon's measurement, that if the inclined sides were to be increased by a regular set of decreasing plates placed upon the surface till they formed an equilateral triangle, they would become oblique octaedrons, (see right hand Jigure j) and if they further continued on these planes till they were lost, they would produce a rhomboidal prism, which, as it seems to agree with the fragments, may be the primitive form. I should have observed that it not only splits into laminae on the broad planes, but that it also rea- dily does so with the side facets. Its fracture is sometimes irregularly conchoidal and glassy. Spec. grav. 2,548. Mr. Chenevix found it to contain oxide of copper 58, arsenic acid 21, water 21. * These two are somewhat magnified. .. - TAB. XXXVIIL CALX carbonata foetida. Botryoidal Limestone with a fatid smell. Class 2. Earths. Order I. Homogeneous. Gen. 1. Lime. Spec. 2. Carbonate of Lime. Div. 2. Imitative. Far. Botryoidal. SYN. Swine Stone. Kirw. v. 1. 89. Stinkstein. Emmerl. v. 1. p. 487. Chaux carbonatee fetide. Hauy, v. 2. p. 188. WE have exhibited the present specimen of limestone as a very curious one, on account of its resembling a bunch of grapes. It seems to be formed by water passing 'through loose marly earth, and consists of smaller or larger globules, according to circumstances ; sometimes in bundles resembling Ketton Stone, (see pi. 8, upper figure,} at other times much larger (see the lower figure in this plate). The globules are occasionally a little hollow, and crystallized within -j sometimes nearly clear, and white, when they are destitute of smell ; but they are more commonly solid and brown within, have a very foetid* odour, easily perceived by scraping or pounding. This smell has been ascribed to * The foetid variety of Limestone is by no means rare. G bitumen, but is of a very different nature. Vauquelin con- siders it as sulphurated hydrogen. The colour is caused by oxide of iron with more or less clay. The odour goes off from the surface if exposed to the atmosphere ; which makes it necessary to scrape it : the heat used in burning it to lime dissipates it entirely. The lower Jigwe is very interesting, as it shows the stra- tification while crystallizing, the darker parts making it evident. The top of this specimen is crystallized with the acute ends of the inverse rhomb, (see tab. 4. upper Jigure,) pointing outwards, which is not unusual in this kind of concentric construction of calcareous earths. Lady Wilson first gave me specimens of this stone, from Sunderland in the county of Durham. Mr. Winch, F. L. S. has since fa- voured me with many varieties of it from the same place. The Rev. John Harriman sent me a specimen from Hartle- pool in the same county ; and it should seem by his obser- vations that this curious stratum may extend from Hartle- pool to Sunderland, all along the coast, and perhaps much further. It is called Building Hill Stone in Sunderland. TAB. XXXIX. and XL. S I L E X arenacea. Siliceous Sandstone. Class 2. Earths. Ord. 3. Aggregated. Gen. 6. Silex. Spec. 2. Grains of Silex more or less agglutinated, Div. 3. Amorphous. SPEC. CHAR. Fracture granular. SYN. Siliceous sandstones. Kirw. v. 1. 364. Cos friabilis. Linn. Syst. v. 3. p. 63. 9. coagmentata. Linn. Syst. v. 3. p. 63. 10. Quartz arenacee agglutinee, ou Gres. Haiiy, v. 4. 464. SANDSTONES may be said to be composed chiefly of quartz in smaller or larger particles, which, according to Kirwan, .should not exceed one third of an inch in diameter. In the representation of such as are not primitive sandstones, it is iltought of much utility to put those which have impres- sions on their surfaces of plants, shells, or other things for- merly organized, that while we acquire a common idea of the substance, it may help geological purposes, which will be found extremely essential in mineralogy, as it leads to the sera of formation of different strata, distinguishing by such helps the more recent from the most remote. TAB. XXXIX. THE upper Jigure is chiefly composed of irregular whitish grains of quartz, cemented to each other by a sort of agglu- tination of its own particles, and in some parts with oxide of iron, which gives it the brownish tinge : it has a few specks of mica, and a very little decomposed feltspar. This was sent me by the Rev. Mr. Harriman from Durham. The lower fgure is perhaps the coarsest sort of sandstone, of much the same ingredients, but of a looser texture, with more decomposed feltspar, and was given me by Lady Wil- son, who brought it from Walmington in Cumberland. The coarseness of the stone shows plainly that it could not have been formed by human contrivance with the present beautiful ornament, but that it is a natural production, which equals in simplicity and elegance some of the most admired ornaments of antiquity, and may, like them, give an useful hint to modem architects. The impressions seem to be like the leafy scales of the stem of some plant yet unknown to us. They are most like some foreign Kuphorbia or Cactus. TAB. XL. THE lou-cr Jigurc* in this plate are of the finest texture: .the particles in the right handjigurc are so fine as scarcely to be discerned without a magnifying glass : the fracture, which is a little shattery as well as earthy, in some parts readily shows the sand-like texture. It is more strong^ 85 cemented in other parts by means of a very little lime, and more strongly still by a siliceous cement. The original of the impression we do not at present know. The particles in the left hand Jigure are somewhat larger, but are more compactly agglutinated by the siliceous cement, and seem as if more or less fused into each other, somewhat ap- proaching the vitreous appearance. The impression seems to belong to some vegetable, possibly furnished with spines in the order where the little ovate knobs appear, which in a specimen lent me by Sir Joseph Banks were rounder, his whole specimen not being compressed*. The upper Jigure with the long squamas is what is called by Kir wan ferru- ginous Sandstone, see v. 1. p. 365. It is coloured with an oxide of iron, which seems to be in that state of oxygeniza- tion on the outside, which has the conglutinating power ascribed to it by Mr. Kirwan, and is consequently more compact on the outside than on the inside. Pebble stones held together in this manner are very common in gravelly places about London. The right hand upper jigure is a coarser stone of a similar nature,, with some pebbles occasionally here and there about it ; also some lumps of a chalky appearance resembling de- composing feltspar, if I may guess by the little remains of the crystal and fracture. Thus it is perhaps next in order * I have figured the specimen given me by Mr. Martin of Derbyshire, as it had an impression on it resembling a bamboo stalk, although Sir Joseph Banks's was better in other respects. 86 to the Rubble Stone of Kirw. v. l . 366. Sandstones are found in many parts of England, and are of great use. They are natural filters in the laboratory of nature, and are now become a modern branch of traffic in Derbyshire, London, and other places, for filtering water. They are brought from Newcastle for grindstones, sharpening of scythes, rubbing down copperplates, &c. Some sorts have been used for buildings, as at Windsor Castle, which is chiefly of the whiter kind and finegrained. The grey and black blotches will be explained hereafter. Mr. Martyn above mentioned has given figures of several specimens of these in his Derbyshire Petrifactions. .v/w '7 Jlaj AWfw I, i,.' TAB. XLI. S I L E X quartzum primitivum. Primitive crystallized Quartz. Class 2. Earths. Order 1 . Homogeneous. Gen. 6. Silex. Spec. 1. Quartz. Div* 1. Crystallized. Var. 1. Primitive. GEN. CHAR. Rough and harsh to the touch. So- luble in the two fixed alkalis ; but in no acid but the fluoric, except (as some think) when in com- bination with an alkali, much diluted with water j also soluble in 1000 times its weight of water. SPEC. CHAR. Nearly uncombined. Burns to an opaque white. Spec, grav. 2.64 to 2.67. Kirw* SYN, Quartz. Kirw. 1. 242. HAUY says that the primitive crystal of Ouartz is the slightly obtuse rhomb, measuring 94 40' and 85 56'. He does not seem to have met with a specimen. Mine, which is formed in a variegated flint, from Lewisham in Kent, showing only one end of the rhomb, agrees with this de- scription, as the primitive : some of them show signs of the other three faces, approaching the double hexaedral py- ramids. See the left hand figure. Silica when transparent and crystallized is commonly called Quartz, Rock Crystal, or Mountain Crystal ; the purest are generally colourless, and often very brilliant. They were 83 formerly much esteemed, and known by the jewellers under the name of Rock Crystals, and Scotch, Welch, or Cornish Diamonds; nor do jewellers seem to distinguish between Rock Crystal and Quartz, although they chiefly use Rock Crystal. It is sometimes found yellowish, or of a topaz colour, passing to red, purplish, brown, black, &.c. Its lustre i glassy ; it is more or less transparent, and is said by most, authors to have a double refraction: we, however, could not discover this circumstance. The fracture is coarse, splintery, conchoidal, or undulating, the flaws frequently iridescent. Hardness 10. Kirw. brittle, strikes fire with steel, and scratches glass. It is the chief ingredient in making glass, when fused with potash, soda, &c. and seems to be only a purer kind of flint. Diamond has generally been classed as the first species of Silex, but it has at length been discovered to be the purest species of Carbon. Quart/. seems very properly distinguished from rock crystal by Mr. Kirwan. The former if exposed to a strong red heat be- comes of an opaque white : this specimen is therefore truly quartz, as I have proved by trying a fragment, which being exposed to a strong heat in a common fire became llr>t of an opaque white, and by longer exposure somewhat opaline, or rather like chalcedony ; not unlike common flint under similar circumstances. Rock crystals on the contrary, ori- ginally dark brown, &c. by the same heat become beauti- fully transparent, as gome lapidaries and jewi-llc-rs well know. TAB. XLII. S I L E X quartzum. var. dodecaedrum, Crystallized dodecdedral Quartz. Class 2. Earths. Order l. Homogeneous. Gen. 6. Silex. Spec. 1. Quartz. Div. Crystallized, Var. Dodecaedron with triangular faces. SYN. Quartz. Sab. 80. Quartz-hyalin dodecaedre. p e Hauy, tab. 40. Cristal de roche dodecaedre. De Lisle, t. 2. p. 70. THE regular dodecaedral crystal of quartz is somewhat rare. I at present know of no certain habitat for it in Great Britain, excepting at Craig Lackart, about 3 miles from Edinburgh, from whence I have an irregular group given me by Dr. P. Murray, who gathered it himself. It is evidently taken from a rock externally in a state of de- composition, as its matrix is porous and mixed with red oxide of iron. It is sometimes found at Bristol, and also on the Lancashire iron ore or haematites, Bab. 80. I have such specimens also on an iron ore from Devonshire. The specimen here figured, I believe, is from Cader Idris in North Wales, and seems to have been thrown off from the- 90 main rock by an ochraceous decomposition : on that side towards the rock it is extremely porous, not unaptly resem- bling French burr, which is used for mill stones. Quartz or silex is not only common in our primitive mountains, but also in our gravel roads. It frequently takes place of animal and vegetable substances, forming petrifactions, or running, like lava or wax, into a mould, occasionally passing into the state of chalcedony, cachalon, &c. Frag- ments of this specimen became opaque in burning, as did that from Scotland. Crystals of specimens nearly dode- caedral on Lancashire and Bristol iron ore are properly rock or mountain crystal, as they burn transparent. *./' J,~.A. 1. ..!,, TAB. XLIII. SILEX granatus. Garnet. Class 2. Earths. Order 1. Homogeneous. Gen. 6. Silex. Spec. 13 ? Garnet. Div. 1 . Crystallized. Var. 1 . dodecaedral, or primitive. SPEC. CHAR. Primitive form, the rhomboidal dode- caedron ; scratches quartz. SYN. Garnet. Kirw. 1. 258. Granat. Emmerl. 1. 43, and 3. 246. Borax granatus. Linn. Syst. ed. 1 3. v. 4. p. 96. Grenat. Hauy, 2. 540. GARNETS are of different degrees of hardness. The Ori- ental and Bohemian ones are of a brighter colour, and are much harder than the British, but all want the aid of the lapidary by thinning them, to show their lustre, and when set by the jewellers are always placed upon a foil. They were much esteemed for hoop-rings, ear-rings, &c. about 40 years ago. The British garnets are commonly much the softest, and not valued by the lapidaries. They are chiefly found inclosed in micaceous and granite rocks, though some- times otherwise. Besides the other ingredients spoken of in garnets, the British ones frequently hold particles of mica, and are of a less firm texture. We, however, have the satisfaction to find them present most of the different forms of crystal- lization. We here give a representation of what is reckoned the primitive crystal, (viz.) the rhomboidal dodccaedron. These are found in great plenty in the Plum-pudding rocks, as they are called, at Huntly in Scotland. We have bought specimens at sales which are said to come from Bohemia, seemingly of the same sort, and in the same gangue as those from Huntly. The Syrian garnet is of a mort scarlet hue, though I have some cut ones, said to come from Scotland, nearly of the same colour., but rather less bright. The lower Jigures arc from rocks near the same place in a lighter-coloured gangue (a granite), with the edges of the dodecaedron forming 24 narrow hexaedral facets, in addi- tion to the 12 rhomboidal faces. I have the same sort of garnet, though lighter, in a basaltic stone, and in greenish hornstone from Scotland. Mr. Jameson has found them in micaceous schistus, v. 1. 21 9. v. 2. 212. External lustre casual, internal 2.3. 1. of the brownish and blackish fre- quently 0. Kirw. Fracture of the hard ones somewhat flinty or conchoidal. Mr. Kirwan calls the oriental garnets carluncles, p. 25S. TAB. XLIV. SHOWS a variety in a lighter granite gangue with the edges more deeply tnmcated on the 6 opposite edges, see the right hand and middle, Jigure, making an 18-sided cry- stal. The left hand Jigure shows the truncation equally deep of a 36-sided figure. The lower ^figure forms a prism by 6 sides being elongated. These varieties are more or U-< distinct in the gangue above. ' V r 1 18 03 fully tuJ t r Ja ' Sr^frfy LenJm 4-5 JSf> fleiU/KeJ tf J* J . Jiftrerly. TAB. XLV. CUPRUM arseniatum, var. amianthiformis. Amianthiform Arseniate of Copper. Class 3. Metals. Order I. Homogeneous. Gen. 4. Copper. Spec, Arseniate of Copper. Div. 2. Imitative. Var. 2. Amianthiform. SPEC. CHAR. Copper combined with arsenic acid. SYN. Amianthiform arseniate of copper. Bournon, Phil. Trans. ISOl. p. 180. N. 2. 4th species, &c. Chenevix, Phil. Trans. 1801, p. 199. 1 HIS species of copper appears first to have been described by Count Bournon. The present variety is a curious ex- ample, and seems so well described by the above author, that we shall transcribe part of his own words. "This variety is composed of fibres as delicate as those of ami- anthus_, of the flexibility of which they frequently possess a certain degree." In the present specimen they resemble the finest filaments of silk. It serves to show a variety in colour not mentioned by Count Bournon, viz. the purple hue, which more or less covers the surfaces or the points of the flexible threads. The other parts are of a lightish straw vellow. Its resemblance to a raceme of currants or a bunch 94 of grapes made me think that each bundle was composed of fibres formed from its centre (as some of the smaller ones are) : but on opening some of them we found an ochraceous gravelly substance in the middle, from which they diverged more or less regularly, often more dense and hard inwardly than outwardly. The more regular ones are commonly more white and satiny than the others, excepting towards the tips, and are more of the texture of rotten wood. The outsides are very tender, and easily bruised. According to the analysis of Mr. Chcnevix, this species contains Oxide of copper 54 Arsenic acid . . 30 Water 16 100 Ifauy mentions capillary arseniatc of copper, v. 3. p. 578. aiid observes "that foreign mineralogists have found different regular forms of arseniate of copper, which from certain cir- cumstances he has not yet been able to determine." Tkt lou'cr magnified figure shows some of the fibres or filaments of both sorts here mentioned, some of which are collapsing at their points as if they had been wetted, forming various reticulations and indentations of a purplish hue, apparently retaining that colour from being less exposed to rubbing or any other accident. This was found in Huel Gorland mine in Cornwall, from whence most of the other arseniates of copper come. TAB. XLVI. THE upper specimen is nearly of a straw colour, and di- verges in a stellated manner from a common centre, with a good deal of the appearance of that kind of rotten wood called Touchwood. I have seen specimens of different shades of green, which somewhat resemble the Byssus-like carbonate of copper, see the surface of the lower figure, where there are also the various colours from straw to dark brown, some of which appear of the colour of darkish brown rotten wood, a little resembling the wood Tin Ore of Cornwall, but may be readily known from it by being so much less heavy than that ore. This appearance occa- sioned the common denomination of Wood Copper, before Count Bournon's paper above alluded to was published. TAB. XLVII. CUPRUM carbonatum, vctr. byssoides. Byssm-like Carbonate of Copper. Class 3. Metals. Order 1. Homogeneous. Gen. 4. Copper, Spec. 3. Carbonate of Copper. Div. 2. Imitative. Far. 8. Byssus-like. SPEC. CHAR. Copper combined with carbonic acid. SYN. Green Malachite. Rashleigh,fasc. 1. tab. 7. /. 6. Cuivre Cabonatee vert soyeuse. Ha'uy 3. 573. Malachit. Emmerl. t. 2. p. 253. MALACHITE Copper ore of this beautiful Byssus-like ap- pearance has been found in great abundance at Llandidno, in Denbighshire. It has rather the appearance of a vegetable than a mineral production, and is most commonly found of a beautiful velvety appearance. The upper surface is extreme- ly tender, and bruises on the slightest touch, assuming a whitish appearance. The sides become more or less white on exposure to the air, and when fresh broken, are of a satiny green, formed of fine thready radii, often closely compacted in stratified order, one coat over another, rightly H 98 compared by Mr. Rashleigh to the coating of an onion. It is found from a light to a dark green ; the surface is some- times tinged with, and passing into a red, or crimson. Its form is generally in protuberating knobs or mammillae. Mala- chites, though well known in many parts of England, have been generally esteemed foreign productions : Dr. Babing- ton, however, mentions the harder sort, resembling the foreign, being found at Helstone, and the Land's End in Cornwall, in the South of Wales and Yorkshire. We have it from Wheal Unity, and many parts of Corn- wall. The softer sort is not unfrequent among copper ores, with the other which we have from North Wales, as before mentioned ; and our friend, Dr. Ridoul, was so good as to give us a specimen which he gathered himself at Dod- dington mine, in Somersetshire. They are said to contain from 66 to 75 per cent, copper, 1 9-4 carbonic acid, and 3'6 water, and sometimes a little arsenic. Hardness, 5-7. Kirw. Spec. Grav. 3-5 to 3'99-i- TAB. XLVIII. CARBO bituminosus. Pit-Coal Class 1 . Combustibles. Order 2. Mixed. Gen. 6. Carbon. Spec. 1. Bituminous. SPEC. CHAR. Bituminous oxide of carbon, and oxide of carbon; mixed. SYN. Mineral Carbon impregnated with bitumen. Kirw. 2. 51. Bitumen Lithanthrax *. Linn. Syst. Nat. ed. 13. t. 3. p. 111. Steinkhole. Emmerl. 1. 60. Houille. Ha'uy 3. 316. De Lisle 2. 590. COAL is a curious, valuable, and well-known article in Great Britain, supplying us with great store of excellent fuel. There are many varieties in different mines, and even in the same mine. The upper Jigure is taken from a com- mon Newcastle specimen, from whence a great part of * Linnasus included all coals under this title, describing them as schistose, which does not include all the species. TAB. XLVIIL CARBO bituminosus. Pit-Coal Class 1 . Combustibles. Order 2. Mixed. Gen. 6. Carbon. Spec. 1. Bituminous. SPEC. CHAR. Bituminous oxide of carbon, and oxide of carbon; mixed. SYN. Mineral Carbon impregnated with bitumen. Kirw. 2. 51. Bitumen Lithanthrax *. Linn. Syst. Nat. ed. 13. t. 3. p. 111. Steinkhole. Emmerl. 1. 60. Houille. Hauy 3. 316. De Lisle 2. 590. COAL is a curious, valuable, and well-known article in Great Britain, supplying us with great store of excellent fuel. There are many varieties in different mines, and even in the same mine. The upper jigure is taken from a com- mon Newcastle specimen, from whence a great part of * Linnxus included all coals under this title, describing them as schistose, which doei not include all the species. 100 England, and many parts of the Continent, arc supplied. It is evidently composed of two sorts of strata, to external appearance sufficiently distinct. The one apparently the remains of wood in a charred state, like charcoal or oxide of carbon. This has hitherto escaped the notice of most authors : besides the grain and appearance of wood, com- mon in this and most other coals, it will be known by being the only part in coal that soils the fingers. If separated, it burns like charred wood, leaving a similar residuum*; it is also soft and powdery, like burnt wood ; breaks in a crumbling manner, and falls into small particles f. The other part is more compact, shining, and brittle, easily scratched with a knife. The least touch of the finger hurts its polish. It has a somewhat splintery conc.hoidal fracture, and seems chiefly carbon mixed with bitumen. It inflames in a moderate heat, yields much smoke, bubbles, and melts something like pitch, and helps the binding or caking, as it is called, (which is the sign of a good coal, at least for housekeeping) and leaves a cinder which lasts a great while, giving a strong heat. The small remains from a common fire are still valuable on that account for the forge. If burnt long in a violent draught of air, it forms a clinker of no value ; We have reason to believe that it contains no alkali. f Mr. J;imcson says, " this does not seem a common appearance," when he found " carbonized wood which could not be distinguished from carbonized Fir." ,. a. p. 37. It i probably the tmut of Mr. Kirwou. 101 which shows it to contain some silex, and, perhaps, iron. Coals are not known to crystallize, yet this glossy part in many has a regular disposition towards it in the partings ; and these mostly have the same angles, forming an upright prism with rhomboidal bases, the angles of which are about 84 and 96*. The middle figure in this plate is a fragment of the New- castle coal ; the completest crystal-like appearance I ever saw. The upper surface is charcoaly, and it rests on a si- milar substance, with irregular strata beneath. Newcastle coal loses about 35 per cent, of its weight while flaming. Linnseus's description seems to belong to the more slaty kind. The lower figure is from a piece of Scotch coal, which was broke through the bituminous strata, in a transverse direction : and shows the glossy fracture, with a sattiny ap- pearance, as well as the angles of partings. This bitumi- nous stratum is commonly somewhat shaly in this sort of coal : the other part is mostly pure charcoal, and often ex- hibits the shape of branches compressed, and the same transverse contractions which take place in charring or burning common deal. This coal loses 25 per cent, while flaming, which it readily does, and continues its heat with * Most mired coals in the common large masses break through the whole stratum more or less in this form : these break* or cracks are called backs, cutters, and partings, by the miners. 102 very little bubbling j flaking and falling to pieces in a slaty form, leaving a whitish ash. Mr. Kirwan describes Scotch coal from Invinc as " hav- ing layers in contrary directions, and being hence often called Ribband Coal. Lustre of the alternate layers 3, 2, (silky and brighter.) Fracture small grained, and coarse grained, curved, foliated. Hardness 4 to 5. Spec. Grav. 1*259. Its composition I have not examined." Mr. Kirvvan's description is very good, but, for the most part, will agree with any stratified coal, viz. the New- castle, Chesterfield, Staffordshire, &c. But this we need not wonder at, from his not having examined the compo- nent parts. I have a coal from Boroughstoneness, given me by Dr. P. Murray, of the kind above described, and some said to be passing into splint, varieties of which are found at New- castle, Wiggan, and other places. These are often con- founded with the Box Coal or Cannel Coal of Kirwan, v. 2. p. 52, the true sort, which is now very scarce. Of these we shall give a fuller account hereafter. We were favoured by Mr. E. D. Clarke of Jesus College, Cambridge, in February 1804, with specimens of Lynn Coal, presenting pentaedral prisms, which he has observed in it for more than a year past. Other coals present this figure, and also trihedral prisms. These are produced by a fracture parallel to one of the diagonals of the base of the, tetraedral prism. t^MBMMM* 1*1^^1 ^^^^^r^ I % _, . ^"^K^GL TAB. XLIX. CARBO oxygenizatus. Oxygenized Carbon. Class 1. Combustibles. Ord. i. Homogeneous. Gen. 6. Carbon. Spec. 2. Oxygenized Carbon. GEN. CHAR. Hardest of all known substances. SPEC. CHAR. Carbon combined with such a propor- tion of oxygen as to remain in a solid state, mostly opaque black. SYN. Native Mineral Carbon. Kirw. 2. 49 *. WE find Mr. Kirwan's description of Native Mineral Car- bon *, Blende-Khole f of Werner, so well agrees with the Denbigh coal, that the chief part of his expressions may with great propriety be made use of. His specimen, he ob- serves, is the purest known, and came from Florence j it depends much upon the choice of specimens to cull the purest j and in the same mine many varieties may be found. * When Mr. Kirwan wrote this, common charcoal was thought to be pure carbon ; it is since found to be an oxide of carbon, and that Diamond is the only native mineral carbon known. Mr. Kirwan's description agree* with oxide of carbon, for which we quote him. f Mr. Jameson calls this Khole-Blend, and observes that it does not stain the fingers. 104 There is little doubt of the Denbigh coal being nearly as pure an oxide of carbon as is likely to be found. tf It> colour is black; its lustre from 3 to 4, approaching the metallic. Transparency 0. Hardness 4 to 5 : brittle : stains the fingers." It could only be the softer part occasionally found in this coal that stains the fingers ; as in that from Swansea, resembling charred wood ; dusty and with less lustre than above-described *, and what he denominates Culm coal of Wales ; another variety which agrees with \vhat Werner calls Glanz-Khole. Denbigh coal is seldom stratified, and is apt to separate with a reedy structure, or impression, in irregular striae. The cross fracture is often conchoidal and undulating. This fracture and the prismatic hues for which this coal is famous, have naturally gained it the appellation of Peacock coal j and it is no less remarkable, that a piece w ith the colours on it, may be heated red hot many times, and, on cooling again, will return to nearly the same appearance, retaining its prismatic hues. We are happy to say Mr. Jameson promises to give a fuller account of his khole-blend, at some early opportu- nity, and has also promised, with his usual generosity, to supply us with specimens. All coals commonly so called produce a black powder. * This, when irregular and loose, as it sometime* is, appear* by the de scription to be the smut of this author. Culm means only unallish coal* of inferior value, which do not pay duty. TAB. L. CAR BO oxygenizatus. Oxygenized C ai -bon . SOME of the Swansea coals resemble the Denbigh coals in their structure, and are nearly the same in quality. This upper figure has the charcoaly and stratified part in various directions. Some parts resemble burnt straw in re- gular rows : others form conical appearances, converging or diverging from a centre. We also find horizontal and oblique strata. The shining part is in various directions, with a confused and shattered appearance. Some of the striated parts were slightly covered with charcoal in fine dust, easily rubbed off, the striated impression still remain- ing in immediate contact with the shining part. In other parts were thick layers of charcoal in irregular strata, but somewhat horizontal to the other parts, the whole having a peculiar, yet confused, appearance. It is very brittle, and easily shattered to pieces. The lower piece is much tougher, and the striae have not a vestige of charcoal about them, nor will they soil the fingers. This seems altogether more indurated. These two and the Denbigh coal have nearly the same qualities as to their uses. They are difficult to ignite, and burn without flame, remaining a long while, and giving a great heat, without much apparent change ; whence they have been de- nominated Stone Coal. They are used for malting, and for burning lime, and are frequently mixed with such coals 106 as will more readily inflame, to assist the burning. They are supposed to contain less oxygen with the carbon than other coals, and therefore require the assistance of those which contain more oxygen. It may not be amiss to observe here that diamonds require oxygen to assist their burning, in the proportion of 4 parts to 5 in a strong heat ; and in burning they pass into the black state of charcoal, continuing to burn like it, and giving out carbonic acid gas (see de- scription, Tab. I.*) in the sarue way, the carbon being aerated by the caloric or matter of heat. Although dia- mond has always been of high value, and well-known from the earliest ages, yet it was left for Mr. Tennant in the year .1 796 to prove it to be a pure carbon . See Phil . Trans. 1797- p. 123. There are other sorts of coals about Swansea, of which we shall speak hereafter. Coals mostly appear to be the combustible remains of vegetation, provided apparently to secure whole forests for the use of after generations. They are mostly formed in the strata of plains, composed of marie, sandstones, and limestones, most of which show the remains of animal and vegetable petrifactions, or im- pressions. See Sandstones, Tab. XL. The blackened parts in those figures are apparently the remains of bituminous carbon, as it were in the last stage of inlillration. * It is found native in some caverns, well?, and mines, and i called chokf damp of the miners. It is often fatal to them. TAB, LI. BITUMEN Gagas. Jet. Class I. Inflammables. Ord. 2. Mixed. Gen. 2. Bitumen. Spec. 1. Bitumen with oxygenized carbon. SPEC. CHAR. Bitumen combined with about 30 per cent, of oxygenized carbon. SYN. Jet. Kinv. 2. 64. Jais. Daubenton 30. De Born 2. 79. Variete du Schlaklges erdpech. EmmerL 2. 50. Jayet. Hauy 3. 324. Bitumen Gagas. Linn. Syst. Nat. ed. 13. /. 3. p. 111. THE upper figure represents a curious piece of Jet, remark- able for the remains and impressions of shells about it. It was sent me from Lowestoft by Dr. Smith, President of the Linnean Society. Jet is well known to have been found on the coast at Lowestoft for many years, where amber and curious pebbles are often found. Some fishermen artists^of the neighbourhood employ their leisure at convenient seasons to search for them, and form the two first-mentioned into 108 small trinkets. We shall consider true Jet to have passed from the remains or' some sort of wood, as the ligneous fibre is in some instances seen; in other specimens it is so condensed and compact as not to be discernible. This substance appears also to be saturated, as it were, with bitumen, insomuch that it readily inflames, losing about 14 grains in 20, with much smoke, and a slight bituminous odour. The remaining cinder, if continued to burn, leaves a very trifling residuum. It is well known to be of the most opaque black (witness the common saying, " black as jet*"); but it will bear a fine polish. Its surface excited by friction possesses the resinous electricity, which distinguishes it from cannel coal, a substance it very much resembles. It may be scratched by common calcareous spar, and will itself scratch amber and gypsum. The fracture is conchoidal, occasionally re- taining that of wood. Lustre 3 to 4; transparency 0. Spec. Gray. 1*104 to 1*744. Kirw. It has generally been said to swim on water. Thin pieces, indeed, laid lightly on the water, will float for a short space of time; but at length the water passes over them, and they sink : perhaps some slight trial of this kind might cause the common idea of its wimming. Of many pieces in our possession none will *wim. Linnaeus called it Bitumen Gagas, from the river Gages in Lycia, near which it was found. The presence of The tt reals or powder is always brows. 109 shells, and the impression of the Comu-Ammonis, indicate its former less indurated state. The lower piece has some signs of incumbent strata hav- ing been on the upper surface, in an obsolete impression, and also some obscure crystals of carbonate of lime under- neath. The fracture is in part largely conchoidal. With some difficulty we may observe the woody stratification. It is truly black. I have a piece where the woody texture is very evident, with small cubic pyrites on one side. With heat and water I decomposed a bit of it, so as very satis- factorily to expose its woody structure. It comes very near to the most indurated Bovey coal and surturbrand *, evi- dently belonging to that division. * These also produce a brown powder. fi&iit ' . TAB. LII. AURUM nativum. Native Gold. Class 3. Metals. Or-1. 1. Homogeneous. Gen. 2. Gold. Spec. I. Natire. Div. 3. Amorphous. GEN. CHAR. Malleable, sonorous, reddish yellow, Spec. Grav. SPEC. CHAR. Uncombined. SYN. Native gold. Kinv. 2. 93. Phil. Tram. 1796. p. 45. Aurum nativum. Waller , /. 2. />. 355. Gediegen gold. Emmerl., t. 2. p. 111. Or natif. Ha'uy 3. 374. Aurum nativum. Z^ZH. S/^^. ed. 13. GOLD is well known to be found in Peru, several parts of the East Indies, and Hungary, often crystallized in octae- drons and their modifications. It has also been found in Scotland. We have specimens from Cornwall and Ireland. We received a letter from Dublin, dated Oct. 24th, 1795, which relates some curious facts that may be worth men- 112 tioning here. " It is strongly maintained in the antient Irish records, that in the courts of their kings and residences of their great men, an extraordinary magnificence was once displayed. That they feasted and drank out of vessels of gold, used it for armour, ornaments of dress, &c. In an age when navigation, and therefore commerce, were cir- cumscribed, it is concluded, that the gold must have been found in the country. Those who doubt this judge from the disregard that has been invariably shown by the foreign settlers in this country to its mineral productions. They presume that it could not have escaped their avarice or their skill, if any thing of the kind worth regarding existed here, and they maintain that the gold must have been procured somewhere from abroad. A recent transaction has showiv that there is probably much gold in this country not many miles from this city. The people of its neighbourhood have long been acquainted with it, and from time to time sold native gold to the silversmiths, but would not tell where they found it. A late disagreement about the division of their treasure caused a discovery. A stream descending from a mountain * runs along a valley at its foot : in the sand of this stream and the sand of the valley on either side are found lumps of native gold." Pieces have been found weigh- ing 22 oz. ; but they are generally much smaller, from 3 ounces to a fc\v grains. It is said some families were in the * Mount OrogUaa near ArUow In the county of Wicklow. 113 constant habit of procuring it*. Endeavours have lately been made to discover the mine, but, as far as we yet know, to no purpose. The upper specimen was lent me by Sir J. Banks, who bought it of an Irishman who brought some to London to sell to the curious ; and this w r as one of his largest specimens. It is formed of flattish pieces, or lamellated, as if it had been rolled up and beaten about very irregularly, as Sir J. Banks truly remarks, so that it may be called entirely shapeless. It was cut in two at the mint, which helped to discover this foliated appearance ; and also, that it contained grains of whitish quartz and an ochraceous gritty clay (see the cut figure], A piece of soft lightish schistus, or slate, with a gray appearance on the inside is to be seen in it. The external colour is somewhat redder than where it is broken or cut. Mr. Blackford kindly sent me a piece somewhat paler. The third figure an the right hand was a piece of a redder east ; that on the left hand was the whitest of any I have seen from Ireland. These two were purchased for me by my friend Colonel Velley. The three lower pieces are different coloured specimens, from Lammon tin stream, near Falmouth, in Cornwall. * We have been told that lumps of gold of a large size have been till lately used as weights in come of the common shops, and others placed to keep their doors open, in some parts of Ireland, the owners not knowing what they truly were. I 114 Gold is much more scarce in Cornwall than in Ireland. The Irish specimen spoken of in Phil. Trans, was found to contain Of Fine Gold 21f Fine Silver If Alloy Copper and Iron Oj Other specimens differ a little ; and thus, if we may judge, by the outer aspect, the reddest probably contains most copper and iron, and the whitest most silver. More silver seems to give a greenish tinge to gold : the little lowest left* handjigure has that tinge. TAB. LIII. CUfRUM oxygenizatuta, var. octaedruni, Crystallized Red Oxide of Copper > Crystal OctdedraL Class 3. Metals. Or A, 1. Homogeneous. Gen. 4. Copper. Spec. 3. Oxide of Copper. SPEC. CHAR. Copper combined with oxygen. SYN. Red calciform copper ore. Kirw. 2. 135" Native oxide of copper. Bab. 174. Roth-kupfererz. Emmerl 2, 213. Cuivre oxyde rouge primitif. Hauy 3.557. SOME of the crystallized red oxides of copper deserve from their lustre the appellation of Ruby Coppers more than others, which will be shown hereafter. The present fine specimen has more of the steel-like lustre, as most of the octaedrons have : however, the beautiful red sparkles in- ternally with much brilliancy. It is not difficult to scrape it with a knife, and the least scratch produces a rich red powder of the colour of the gum called Dragon's Blood *, * Known in the Pharmacopoeia by the name of Sanguis Draconis, and ex- tracted from Calamus Rotang of Linnaeus. 116 The specimens look red most by candle-light. They are found in Wheal Unity, near Redruth, in Cornwall, and in other parts of that county, as well as in different parts of Europe. Foreign specimens, as far as I have seen de- scribed, seem not to be superior in the size or perfection of their crystals to the Cornish ones. The matrix of our upper figure is shatter}' quartz, supporting native copper, from which the oxide seems to proceed. It is worthy of remark, that this kind of oxygenizement should form so regular a crystallization, for it appears to be only a decomposition of the native copper from which it commence*. The lower figures are in different matrices, one in a red powdery oxide of copper and iron ; the other in an ochra- ceous matrix, chiefly oxide of iron. It agrees with the following parts of Mr. Kirwan's de- scription : " It is often cochineal red, or intermediate be- tween blueish-ffray and carmine red. Found massive, in- vesting, disseminating:" he does not mention its being found crystallized. " Fracture even, approaching to the minute conchoidal, sometimes earthy. Hardness 4 to 5, brittle. Effervesces with nitrous acid, to which it gives a green tinge, and a blue to caustic volalkali." Thus much till Mr. Chenevix had shown that there was only one proper oxide of copper of a black colour, and that the present species is rather a suboxide of copper, con- taining Copper 88'5 Oxygen 11-5 whereas the black oxide contains 20 per cent, of oxygen. m. TAB. LIV. FERRUM suboxygenizatum, Magnetic Iron Ore, Class 3. Metals. Order 1. Homogeneous. Gen. 6. Iron, Spec. 2. Magnetic. Div. 1. Crystallized. SPEC. CHAR. Iron in combination with but a small portion of oxygen *. SYN. Iron in a calcined state mineralized by pure air. Kinv. 2. 157. Magnetischer Eisenstein. EmmerLV. 278. Fer oxydule. Hauy 4. p. 10. Ferrum tesselare. Linn. ed. 12. t. 3. p. 136. 3> yji rr. i , Ln "^***" " ~~ I WAS much pleased when I discovered this curious crystal- lization in a pyritaceous copper ore sent me, among other favours, from the neighbourhood of Tavistock, by my kind friend Mr; John Taylor junior. The crystals are dispersed through the ore in tolerable abundance; but being small, do not readily distinguish themselves to the unassisted eye: with a lens, however, they are very satisfactorily seen, with the variety of modi- fications here figured, and sometimes, by breaking them, we find them curiously casing each other 2 or 3 times. They are most readily attracted by the magnet, and will support a part of the gangue of pyrites that may chance to be attached to them, of 8 or 10 times their own bulk. Tfie gangue is said to be rich in copper, and is commonly of a bright and pale golden colour, sometimes with a greenish hue, and often iridescent. * 15 to 24 per cent. Kim: vol. 2. 158- 118 I do not know that this crystallized variety of magnetic iron ore has been observed in Great Britain before. Dr. Badham gave me a fine octaedron of the Swedish sort, from Fahlun (where such specimens are not rare), which is above half an inch in diameter : but this is not more strongly attracted by the magnet. It is coated with mica, and, within, is of a more or less deep-brown red, as are ours, sometimes ap- proaching steel-gray and black, partly shining, and metallic. Fracture uneven, somewhat earthy. The crystals are ar- ranged in convenient order, to see the additions that assist in modifying the different crystallizations, (viz.) Tfie upper Jigure on the right hand exhibits the regular octaedron, the faces of which, by the addition of the la- minas of superposition, or superior coating, form long six- sided facets, which are those of the dodecaedron with eight triangular faces parallel to those of the octaedron, see the middle Jigure. These are the nearest approach we have seen to the octaedron in our specimens; with more laminae, it keeps the same form which is shown, but with smaller tri- angular facets in the left hand figure and the right~hand lower Jigure. In the lower Jigure on the left hand the laminae have advanced so far as to form the complete rhomboidal dode- caedron. The geometrical outline shows this manner of casing over each other; but we must beg our readers to substitute the octaedron in lieu of the dodecaedron in the centre, as we find is the case upon further examination since the engraving was finished. v TAB. LV. SILEX quartzum, var. arenaceum. Sandstone. Class 2. Earths. Order 1. Homogeneous. Gen. 4. Silex. Spec. 1. Quartz. Div. 3. Amorphous. Var. 2. Graniform. SYN. Ferruginous Sandstones. Kirw. v. 1. p. 365. Cos colorata. Linn. Syst. Nat. ed. 13. v. 3. p. 64. SANDSTONES are not uncommonly impressed with the casts of shells, 8cc. They are little else than granulae of flint, with iron more or less oxidated : the oxidation is most con- spicuous in the crevices where the shell has been mixed with a little lime, or other things, giving them different tints. The shapes of many sorts of shells are found in these stones, mostly Areas and Anemias. The acuminated sides of the Area on the stone at the right hand seem accidentally formed, from the peculiar manner of its immersion in the mass. They are often found detached as figured, and serve to undeceive us. These Arcae, as they surely are by the length of the hinge, apparently contain many denticula- 120 tions, or teeth *, the distinguishing character of the gentig. The singular rising in the middle of the upper shell, of about 5 pleats wide; and the corresponding cavity in the under one, is a curious character, common, with some variations, to both these and the Anomia, with which they have gene- rally been confounded. The little Anomiae at the bottom are darker, and probably contain more iron. Their struc- ture is certainly remarkable, especially as we, in the present age, have no recent shells in this part of the world at all corresponding with them. We think these the more in- teresting on that account, as they help to indicate, that at certain periods there were some animals very different from those now existing. These were sent me from the Tees by the Rev. Mr. Har- riman, and also by Mr. Winch, in large fasciculi. They are found in other parts, but I do not know how near the present surface of the earth. They are but little crumbly in their fracture, rather con- densed, and approaching to the conchoidal, like flint : they are often very tough, but too heavy for building, and not of any known utility at present : they, perhaps, might be liable to decay, as the ochraceous substance is somewhat scattered through them. They sometimes contain more or less clay. * See Area, t. XT. p. 35. TAB, LV1. FERRUM oxygenizatum, var. radiatum. Radiated Oxide of Iron, or H&matites. Class 3. Metals. Order I. Homogeneous. Gen. 7. Iron. Spec. 3. Oxide of Iron. D'w. 2. Imitative. SYN. Red Haematite. JCirw.v. 2. 168. Rother Glass-kopt. Emmerl. v> 2. 313. Hematite. Hauy, v. 4. 105. De Born, v. 2. 287, XI, F. c.b. 1. THE Haematite Iron ores are found near Silverstein in Lan- cashire in great variety and abundance. The upper speci- men is somewhat singular, from the separating and divari- cating radii. The lower figure shows more of the usual struc- ture of these ores, which often form large roundish or irre- gular nodules, sometimes kidney-shaped, botroidal, 8cc. the masses radiating from one or more centres, 6 inches or more in length, and casing or coating one over another. They are mostly of a brick red colour, easily staining the fingers, particularly the powdery parts : the harder parts also stain the fingers much, and by a little rubbing give a black tinge 122 with a bright lustre not unlike black lead. Those parts which have lost the red appearance, and approach the me- tallic or iron lustre, do not so readily stain the fingers. On being ground these give a deep red colour; whence this ore has been called Blood Stone. Sometimes the harder black sort with this property is cut into burnishers for gilders. These ores are said to contain from 40 to 80 per cent, of iron. The harder kind is sometimes a little magnetic, if reduced to powder, particularly if heated on charcoal ; which deprives it of a certain quantity of oxygen. " Fracture coarse or fine fibrous, parallel or diverging, earthy." Hard- ness, from such as may be easily scraped with a knife to such as will strike fire with steel. Spec. Grav. from 4 to 5, Kirwan. " This ore contains, besides some manganese, a large proportion of argill, which renders the iron it affords red- short, that is, brittle when red hot." Kirwan. TAB. LVII. SILEX Analcimus, var. compactus. Compact Analcime. Class 2. Earths. Order 1. Homogeneous, Gen. 4. Silex. Spec. 9. Analcime. Div. 3. Amorphous. SYN. Analcime. Haiiy, v. 3. 1 80. J- HIS curious substance is not uncommon in Great Britain, wherever basalt and trap are found. We have some spe- cimens from different parts of Scotland, which contain it in nodules. The present specimen came from the Isle of Isla. It is somewhat stalactitical, and extremely various in its shapes, sometimes forming roundish drops from the size of a pin's head to that of a large pea, and often of a knotty elongated figure like a potatoe. It seems to be a transition from quartz, and decomposes into filaments forming zeo- lite. This specimen exhibits it beginning to form filaments. The bottom of the larger mass, which somewhat resembles the humerus, or thigh bone, of an animal, appears once to have been in a thick fluid state, and might give some idea of the forming of the flints in chalky rocks, (see page 15.) K 2 124 which however is not quite satisfactory to me. More of this will be mentioned in another place. They may be found somewhat various in their colours. The most Common are nearly as here represented; transparent white or glassy, and often pearly or greyish within j the outside being coated with a light brown crust often nearly opaque, which gives an idea of fresh cast wax. The fracture is irregular, glassy or flinty. Analcime may be found in most of these appearances so hard as to resist a knife, like quartz; but in the state of compact zeolite, or passing into fibres, it may be scratched with a knife or any steel instru- ment, though it resists iron and brass. We are not sure that this is the true hyalite of Kirwan; who says it does not fuse per se at 1 50. Ours fuses per se at the heat which turns carnelian white, which Kirwan observes was 160. TAB. LVIII. SILEX Analcimus, var. fibrosus. Fibrous Analcime in Trap. Class 2. Earths. Order 1. Homogeneous. Gen. 4. Silex. Spec. 8. Analcime. SYN. Zeolite. Kirw. v. 1. 278. Analcime radie. Hauy, v. 3. 182. ZEOLITE, formerly so called, is often found in trap, as if passing from opaque hyalite of Kirwan (see our Tab. 57.), at length leaving the spaces where it was first formed empty, and giving the stone the appearance of a scoria or basaltic lava. This is a red variety of basaltic trap, which has hyalite of a pebble-like appearance in one part. In some cavities it has partly fibrous zeolite; in others the zeolite appears in fine filaments, sometimes of a silky lustre, filling the holes like cotton or with loose threads, which are often scattered more or less in irregular bundles, somewhat radiating. The hollows which contain these are mostly lined with small crystals. These at first sight look like quartz, such as often sparkle in common flints, but if examined with a glass their structure determines what they are. See Tab. 59. and magnified figure at the middle and bot- tom of this plate. We use the old term of zeolite, as being most familiar; at present it is synonymous with analcime. f, .r.,' .. TAB. LIX. SILEX Analcimus. Analcime. Class 2. Earths. Order 1 . Homogeneous. Gen. 4. Silex. Spec. 16. Analcime. SPEC. CHAR. Primitive form, the cube. Spec. Grav. about 2. Electricity difficult to excite by friction. Vitreous. Fusible per se into a transparent glass. SYN. Vesuvian or white Garnet. Kirw. v. 1. 285. Wurfel zeolith. Emmerl. v. 1. 205. La zeolithe cubique. Brock, v. 1. 304. Analcime. Hauy,v. 3. 180. VESUVIAN or white Garnet* is the only substance men- tioned in Kirwan that at all agrees with this species f : but in thiSj as in many other substances described by that great author^ he does not observe whether he had ever seen any thing like it found in Great Britain. * The substance commonly called Fesuvian should not be confounded with this, as it is a very different substance which is called Jdocrase by Haiiy, 2. 574. and is mostly of a dark colour, but is probably included under Mr. Kir- wan's ] 8-, 36-, and 5C-sided crystals of Vesuvian Garnet. f Including only his 24-sided crystals. 128 The specimen here figured came from Kirkleston, 8 miles west of Edinburgh, and seems always to present the same crystallization more or less compressed. The crystals vary in transparency from translucid to nearly opaque white, and are often of a pale red, sometimes of a dull salmon colour. I was favoured with some of these from Calton Hill near Edinburgh by Mr. Neale. The fracture is often very confused, and somewhat like quartz after being dropt red hot into water. I however had the good luck to find one, among many specimens sent me by Mr. J. Murray of Edinburgh, with the proper cubic fracture, which leaves me no room to doubt that the crystals here figured belong to the cubic zeo- lite of Brochant. The Dumbarton crystals that I have seen are also the same species. Mr. J. Murray, who sent them to me, is of the same opinion. The rock however in which they are found differs, as well as the manner of Iheir immersion. Those figured are in grunstein* of Wer- ner, (see Kirwan 1. 353.) and situated in hollow cracks or fissures. Those of Tab. 58. are lying in hollows or moulds, and are apparently the residuum of the substance which previously filled the space. Mr, Kirwan speaks of Vesuvian garnets from the size of a pin's head to that of an inch. We have some which differ in appearance only by a dirtier hue, the gangue often partly sticking about them, which is of a muddy brown : the mould or holes they were in are some umooih and some rough. This is the amphigene of Haiiy, and might be confounded with the analcime : but the latter Hornblende and felspar. 129 can be fused by the blowpipe ; and if of the transparent kind, it at first becomes opaque : if the heat be continued \i becomes transparent, and at length fuses. The opaque first become transparent, and then fuse. Mr. Kirvvan says the Vesuvian garnets fuse per se : but our Vesuvian garnets appear to agree with what Haiiy says of his amphigene, (viz.) that it is infusib.le, although the analcime may be fused : both sorts are said to be found at Vesuvius. The hyalite, zeolite, and analcime of these 3 plates seem nearly allied * } and by some are thought to be varieties of each other. We hope, however, analysis will soon clear up the point. Haiiy takes his name from the weak degree of elec- tricity this mineral receives by being rubbed ; and we have found it just capable of holding a hair for a short time. * As they are all fusible per se by the blowpipe, and agree somewhat in this particular with the Scotch phosphorescent zeolite, of which the analysis is given by Mr. Kennedy in the Phil. Magazine ; it is desirable for that gen^ tleman to examine the difference, and favour the world with the result. TAB. LX. FERRUM oxygenizatura, var. radiatum< Radiated Oxide of Iron, or Hematite. Class 3. Metals. Order 1. Homogeneous. Gen. 7. Iron. Spec. 3. Oxide. Div. 2. Imitative. Var. radiated; SYN. Brown Haematites. Kirw. v. 2. 163. Brauner Glass-kopf. EmmerL v. 2. 323. Fer oxide Haematite. Haiiy, v. 4. 105; THIS variety of haematitic iron ore, with which I was fa- voured by Mr. Murray, comes from near Edinburgh, and has not long been discovered. Tt has much the appearance of crude iron, with nearly the same shining fracture in the direction of the radii, but blacker and duller in the opposite direction. These radii sometimes terminate like brushes in the matrix, which is a brown clay. It is not magnetic. Some of the variety figured at Tab. 56. is occasionally found about it. The ends are some of them terminated beyond the matrix, like the ends of a bunch of wires, or obscurely crystallized with the ends approaching those of Tab. 62. and 63. Mr. Kirwan says, " seldom steel grey. " External lustre 2, 3. Internal lustre 2, 1. " Spec. Grav. from 3- 789 to 3'951. Streak reddish or yellowish brown." In ours the powder is the same colour as the streak. " It is not magnetic until calcined. Before the blowpipe, it blackens, and gives to borax a yellow tinge with some effervescence." We do not know that this has betn analysed. TAB. LXI. FERRUM argillaceum. Argillaceous Iron Ore. Class 3. Metals. Order 2. Mixed. Gen. 7. Iron. Spec. 1 . Argillaceous. j* SYN. Common argillaceous Iron-stone. Kirw.v.lfS. Lowland Iron Ore. Bab. 199. AMONG other iron ores a great deal of the sort above figured is used. It is chiefly iron mixed with clay, produ- cing 30 to 50 per cent, as we have heard. This variety is ad- mired for its being divided into polygonal columns by cal- careous spar. It is found in round or compressed lumps, called by the miners cats' heads or cats' scalps. It appears that the iron clay in lumps has cracked inter- nally, and that calcareous earth has crystallized in the fis- sures*. The upper Jlgure shows it as it commonly appears when cut. Bitumen is sometimes contained in the cracks, as are various other substances. In the middle Jigure the calcareous spar is mixed with blend, and is more concen- * These divisions depend on the vicissitudes of wet and dry, hot and cold, and approach to the nature of the Giant's causeway in Ireland, &c. 132 tratcd. It was brought to me from Scotland by Dr. Peter Murray. The lower figure is similar to the uppermost, except being externally in a state of decomposition, probably from expo- sure to the atmosphere among the tumblers (as they call the stones in common) in the river Tees. We received it from the Rev. Mr. Harriman. Its redness is caused by the oxy- genization of its iron. The outside is so far decayed as to expose the divisions of carbonate of lime. These are called septariums, of which there are various sorts j and besides those of iron stones there are to be found some of marie of various sizes, at Bristol, the Isle of Sheppy, Richmond, and many other places. The sort in the upper figure is often so much admired after being split that it is frequently cut and polished. The frac- ture is conchoidal, earthy, and the component parts more or less regular in their mixture, holding Iron, Clay, Lime, Silex, and Manganese, TAB. LXII. CALX carbonata ferrifera, var. lenticularis Spathose Iron Ore; Lenticular crystallized Carbonate of Lime. Class 2. Earths. Order 1. Homogeneous. Gen. 2. Lime. Spec. 4. Carbonate of Lime. "SvN. Calcareous or Sparry Iron Ore. Kirw. v. 2. 190. Spathose Iron Ore. Bab. 201. Spathiger eisenstein. Emmerl. v. 2. 329. Chaux carbonatee ferrifere lenticulaire. Haiiy, v. 2. 178. Mine de fer spathique. De Lisle, v. 2. 281. THIS singular group of spathose iron ore, as it is often called when gathered with the iron ores of Devonshire, may with as much propriety be called a calcareous spar. The crys- tallization is found to be as it were intermediate between the latter and the former. The top left hand figure shows the primitive rhomb somewhat flattened, formed by aggre- gations of the primitive rhombs of calcareous spar. See Tab. 2, 3, and 13. The right hand upper figure differs only in having the apex truncated, and the edges having rounded facets. The lower left hand figure shows the same with the rounded facets having become the principal faces of the crystal. It is altogether rather flatter and rounder. The lower figure on the right hand is still flatter and rounder, and approaches more to the irony appearance. 3 134 The first is a pearl spar of the usual light appearance, the second more coloured with iron, the next more so still, and the last most of all. They may perhaps contain a little manganese. The outline shows the position of the primi- tive rhomb in the upper Jigtures, in the others it is situated as in the acquiaxe. Some specimens of these were sent me by Lord Heathfield from Devonshire. I have had others of nearly the same nature from the Isle of Man by favour of the Duke of Athol and Lord Henry Murray. They seem to indicate iron in their neighbourhood, and may be useful in smelting it; but are themselves very deceitful, their ap- pearance giving a stronger indication of iron than be- longs to them ; which will in general be detected most readily by breaking, as the fresh fragment discovers them to be a mere limestone with a slight pearly tinge, which on being exposed to the common air and water will assume the same deceitful tinge as the former exposed parts. These have generally been reckoned among the lenticular ores, and may have deceived many by their external appearance. TAB. LXIII. THIS is nearly the same, with very flat lenticular crys- tals standing edgeways, of a dull rusty appearance, the matrix nearly of a similar substance, with some lustre. The whole shows the gradation of tints, and the fresh fractures are lightest, as is common in these varieties. The left hand Jigure has some signs of the triangular and other faces partly remaining; in the right hand Jigure they are entirely lost: the middle Jigure exhibits a transverse section, fresh broken, with signs of the confused rhomboidal fracture. TAB. LXIV. FERRUM oxygemzatum. Foliated Oxide of Iron. Class 3. Metals. Order 1. Homogeneous. Gen. 7. Iron. Spec. 3. Oxide of Iron. SYN. Plumbaginous or Micaceous Iron Ore. Kirw, v.2. 184. Eisen-Glimmer. Emmerl. v. 2. 306. Fer oligiste ecailleux. Haiiy, v. 4. 45. THIS curious variety of iron ore is found in Wales, Scot- land, Cornwall and other places. It has the appearance of iron with somewhat of the gloss and the blackish grey tint of black lead, occasionally with the blue, purple, and some- times the other iridescent colours. It is more or less flat, irregular or undulating, in very thin broad laminae, one over another. They have two sets of parallel lines crossing each other obliquely, and forming the plain of a rhomboid. It is found in rocks of quartz, and the upper figure has some yel- lowish mica about it. The right and left hand middle figures show the parallel lines crossing some fragments, and the un- dulating structure. It is not attracted byythe magnet. It is very brittle, and easily breaks into small irregular frag- ments. 1 136 The sparkling middle figure is known by the common name of glimmer, or scaly iron ore, and often accompanies the above, as well as the black and red haematites. It is blackish or red occasionally. The little bright faces of the scales reflect die light with great brilliancy, particularly by candle light, as the figures will show with the utmost ni- cety, as the very substance was of necessity used for its own representative. The biggest Jigure is among broken quartz or rock, covering the surface or filling little hollows in a scattered manner. The lower Jigures are aggregated bundles, which are often found much larger: they have some- times a tendency to crystallize in small rhombs, but I have not yet seen them large or distinct enough to be measured. The angles appear to be the same as in the foliated part above, to which the lower evidently belongs. It is found in Devonshire, whence we received it by favour of Colonel Montague and the Rev. A. Neck. The same was also sent from Scotland by Mr. Winch. The upper one was. received from Wales, by favour of the Rev. Mr. Williams. TAB. LXV. STRONTIA carbonata. Carbonate of Strontia. Class 2. Earths. Order 1 . Homogeneous. Gen. 5. Strontia. Spec. 1. Carbonate. Div. 1. Crystallized. GEN. CHAR. Soluble in 200 parts of water at a tem- perature of 60. Separates from a saturated solu- tion in nitric acid, in the form of rhomboidal crystals. Promotes the fusibility of most other earths. Most of its salts tinge flame red. SPEC. CHAR. Combined with carbonic acid. SYN. Strontian earth combined with fixed air. Kirwan, v. 1. 332. Strontian carbonate. Haiiy, v. 2. 327. THIS curious mineral was found some time since at Stron- tian in Scotland, in a lead mine which is now given up, as it would not answer the purpose of the proprietors 3 but seems not to have been suspected to contain a new earth until Dr. Craufurd sent it to Mr. Kirwan in 1790. It was afterwards examined by Dr. Hope and others. We do not know that it has been found any where else. Its crystals are con- fusedly grouped, more or less diverging from a centre. They sometimes show the appearance of a six-sided prism, as Hatiy has observed. L 138 The specimen figured w as sent me by my friend Mr. Sims of Norwich. It has 6-sided prisms, terminated atone end with three faces, resembling those of carbonate of lime, with the obtuse aequiaxe termination. We have a specimen with six- sided bars quite relieved crossing an hollow : three faces of the prism are generally broader than the other three, showing faint longitudinal striae and fractures parallel to them; but most readily to the three broader faces with transverse striae, which continue to the apex of the pyramid, and occasionally form an equilateral triangle. The pyramid may be divided in a direction contrary to its faces j therefore the nucleus is a dodecae'dron with rhomboidal faces. They vary in colour from a brightish watery green to a palish brown. It differs from carbonate of barytes (with which it was once confounded), by its weight, as well as by dissolving quickly, and with great effervescence, in nitric acid, without leaving a precipitate: and it is cu- rious that a bit of paper or a wick of a candle, dipped in this solution, after being dried, causes the flame to burn beautifully red ; or the substance itself in fusion by the blow- pipe will do the same thing. Spec. Grav. from 3.4 3.675. Hardness 5, according to Kirwan. Scratches carbonate of lime, and is scratched by fluate of lime. Analysis by Pelletier: Strontia - - 62. Carbonic acid - 30. Water - - 8. 100. It is accompanied by carbonate of lime, sulphuret of ba- rytes, sulphuret of lead, and harmotome of Haiiy, or stau- rolite of Kinvan. ee. TAB. LXVI. FERRUM oxygenizatum, var. crystallizatum. Crystallized Oxide of Iron. .^ Class 3. Metals. Order 1. Homogeneous. Gen. 7. Iron. Spec. 3. Oxide of Iron. Div. 1. Crystallized. GEN. CHAR. Colour grey. Harder than most other metals. Attractible by the magnet. Spec. Grav. 7.2 7.84. Kirw. Capable of combustion by collision. Bab. Soluble in all the acids ; precipita- ble from its solutions, the precipitate being of a blue colour, by prussiate of potash. SPEC. CHAR. In combination with above 24 per cent, of oxygen. SYN. Specular iron ore. Kirw. v. 2. 1 62. Fer oligiste. Hauy, v. 4. 38. THE peculiar form of this minute crystallization I could not pass over, especially as it may be a very proper one in arranging the varieties of the species to which it belongs. The sort of iron ores from Lancashire, on which these crys- tals are sometimes found, is not uncommon : there are also 140 minute quartz crystals, frequently very transparent, attached to this ore; which on the dark ground deceive us with the idea of crystallized iron ore : however, with the help of a lens, it may often be discovered whether we are right or not, by the form of the crystals. The latter, although a seeming modifi- cation of carbonate of lime, appear to be slightly magnetic. It is a very curious circumstance that this should so gene- rally resemble, in the form of its crystal, the carbonates of lime, this being like a flattened asquiaxe with various modi- fications. Rome de Lisle's, p. 4. f. 62. is the nearest re- sembling it, wanting only the 6 alternating narrow faces. The fracture is intermediate between glassy and splintery, and when fresh broken it shows an iron or steel-like lustre. The outsides of the crystals are of a darker iron or steel-grey with much gloss or polish ; the edges of some resemble blued steel, and sometimes reflect other colours. They stand edgeways on the matrix ; which makes this hue more conspicuous, and adds much to the beauty of the specimen, especially when magnified. We presume this is the same as the beautiful iron ore from Elba, now first noticed in England. TAB. LXVII. CALX sulphate*. Crystallized Sulphate of Lime , or Gypsum. Class 2. Earths. Order 1 . Homogeneous. Gen. 3. Lime. Spec. Q. Sulphate of Lime. SPEC. CHAR. Lime combined with sulphuric acid. SYN. Broad foliated Gypsum. Kirw.v. 1.123. Gips et Fraveneis. Emmerl. v. 1. 527. 540. Chaux sulfate trapezienne. C i P. Hauy, v. 2. 270. Natrum selenites. Linn. Syst. Nat. v. 3. 91. SHOTOVER Hill, Oxfordshire, seems to afford the clearest and cleanest specimens of crystallized gypsum in the great- est variety : yet we find some varieties are rather local, as shall be shown hereafter. They are mostly found 'in a clayey gangue. The upper Jigure is what Haiiy calls trapezienne. Although this would by extending the lateral faces, which might be easily done by piling plates on the summit, each smaller than the last, form an octaedron ; yet of a great many varieties which we have seen we have not observed this mo- dification. The middle Jigure shows a very frequent variety from the same place, heightening towards an octaedron; but seldom extending much further than this figure. They often have their angles a little irregular, so as not to meet : see the left hand corner near Jigures 1 and 2, also having other crystals sticking in them in different directions. If * The specific name at tab. 21. should be read Calx sulphata, and not sulphurala. 142 (he laminae are opened in the manner of a flaw or crack, when not too wide, they admit the prismatic rays : see the upper face <>f middle figure and middle face of lower figure. They are said to admit of double refraction by mostminera- logical writers. Fig. 1 . is a darkish spot of clay or soil naturally in the subject, and Jig. 2. is the same seen a little duller through the other face at the same time : but this is common to all transparent substances. It is somewhat curious that the clayey stripes or spots have a particular direction diagonally to the acute angles. Spec. Grav. 2.2642 2.3117- Kirw. and Ha'uy. They are laminated, the laminae somewhat flexi- ble; easily separated. Hardness, yields easily to the finger nail. The bottom Jigure shows three crystals mixed together, and forming what is commonly called a macle. TAB. LXVIIT. Is a variety from Bedfordshire, sent me by favour of the Rev. T. O. Marsh, showing a tendency of the laminae to se- parate and bend, which they will generally do in the longitu- dinal direction. Thus, a plate of gypsum will be found to break less readily in this direction, always bending before it breaks, and then generally ruggedly. In the other direc- tions, it is either glassy or foliaceous. When these crystal- lizations spread like the lower fgures, they are commonly called Lions' paws. Crystallized selenitcs are the moon- stones of Gesner and Agricola. See Plott's Oxfordshire) p. 81. 2 68 T A B. LXIX. ARGILLA duiissima. Scotch Corundum. Class 2. Earths. Order I. Homogeneous. Gen. 2. Argil. Spec. 8. Corundum. GEN. CHAR. Unctuous to the touch. Easily diffusible in water. Adheres to the tongue. Spec. Grav. 2. Kino. Combines difficultly with acids, form- ing with most of them deliquescent salts, soluble in borax. Bab. SPEC. CHAR. Nearly pure argil, hardest of all mine- rals except the diamond. Divisible parallel to a rhomb, the angles of which are 86 26'. 93 34'. THIS curious substance was sent me among other things from a dealer at Aberdeen, under the name of Red Schorle from Achen-door. I figure it here, because it is a substance which appears to be new to British writers. Upon inquiry I found it was very little known, nor was it to be found in any mineralogical collection in London, nor scarcely in Scotland. I therefore was glad to present a few of my friends with it. Even Mr. Jameson had not previously ob- tained it. From him I hope for a good account of it. It occurs in long columns or bars from an eighth to three quarters of an inch thick, mostly confused, often diverging 144 and with transverse flaws, having the matrix intervening abruptly. Its fractures are longitudinal and splintery. The columns are four- sided, with faces replacing the edges in the centre of the angles : on one, two, or more sides, the ends approach towards a pyramid (in such as I have seen) with four rhomboidal faces. Among a tolerable quantity, I found very few with crystallized terminations, as figured : the faces however are very distinct. We find this fossil has been taken for a rubellite, and Kirwan's description in a great measure accords with that idea. See Kirw. v. 1 . 28S. but in many respects it has been confounded with the titanite of Kirwan. See his description. May the radiating variety be the substance of which Mac- quart says the garnets are formed ? He describes it as con- sisting of straight fibres diverging from a common centre. Set Kirw. v. 1. 261. Its common appearance resembles garnet much, but it is not fusible by the blowpipe, whereas garnet is fusible into a black enamel. Kirwan mentions red schorl, p. 27 1> and says rubellites are also so called. Another substance resembling this, according to the short description of Mr. Kirwan, was found by Morveau in Poitou, v. 1. 336, which he presumed to be adamantine spar. Again, as Haiiy observes, another men- tioned by M. Morveau, found in Le Forez, resembles it greatly, and which is of great hardness. See Kirw. 337. Hardness of ours nearly the same as that of spinelle. We found that the harder spinelles would scratch it ; but the softer ones are scratched by it. This seems undoubtedly the " Spath adamantin d'un rouge violet" of Bournon, which he described in the year 1789 from specimens found in Le Forez, (Journal de Physique 453.) and now considers as a variety of corundum. Other authors have had a similar idea. We here subjoin a part of his description: see 145 Phil. Trans, for 1802, 323. where quoting Hauy, v. 4. 562. who observes fig 78 to 89- However, the faces o on figs. 81, 85, 86, 87, 88, 89 ap- proach it ; but the angle of incidence is that of the rhom- boidal dodecae'dron, or 120; whereas ours is that of the dodecaedron with isosceles triangular faces. Most of the crystals in this group are truncated at the edges, like^. 27 162 of Rome de 1'Isle (see our geometrical Jigure at the bot- tom). These sloping truncations add 12 narrow pentagonal faces ; and thus we have a new figure with 28 faces. Copper pyrites may be known from iron pyrites by its brassy colour, smooth fracture, and not striking fire with steel. Q o I TAB. LXXIX. CALX carbonata ; var. petrosa. Variegated Limestone; or Tirie Marble. Class 2. Earths. Order 1 . Homogeneous. Gen. 3. Lime. Spec. 4. Carbonate of Lime. Var. 3. Amorphous. SYN. Common compact limestone. Syst. Mm. Jame- son, 477. THIS beautiful variegated limestone comes from the hill of Belephetrich in Tirie, one of the western islands of Scot- land. It is said to be a primitive limestone, but is not mentioned in Mr. Kirwan's Geological Essays. It has all the common characters of a limestone, with a fine splintery fracture*. It is admired for the white and red, blending and softening into spots, blotches, and undulating strise, more or less interrupted by bright little red stones sticking within it like little garnets f, which are somewhat trans- parent, smooth, irregular, and seem to be quartz (see the lower red-coloured figures] : also white transparent calca- reous spar with the common rhomboidal lamellar fracture is occasionally mixed with the stone j but more especially a light or dark olive green substance, either of an earthy or * Primitive limestone is not always white, nor is the grain of it always very perceptibly scaly or lamellar; but approaches, by reason of its minuteness, so nearly to the compact as to pass for such: nay, it is said sometimes to discover a splintery fracture, but very rarely; sometimes its texture approaches to the fibrous. Kirwan's GfoL Ess. 215. f Jameson says it contains little garnets : we do not find any in the quantity of some tons which we have had the opportunity of examining. 164 shining appearance. The earthy sort at first sight resembles chlorite, but is more or less rhomboidal in its fracture. It seems to be mixed with quartz, and is irregular as to hardness. This green substance is mostly very irregular a$ to shape. We could only discover a small inclination to hcxangular columns with irregular ends: these are some- times smooth and shining, and have whitish transverse strice, which give them the appearance of an onyx : these striae are softer than the other parts (see the middle fgures) : some of these have a resemblance to jade, as Raspe ob- served, but perhaps only from their outward smooth aspect. The lighter ones, we presume, differ only in colour, and arc probably the same substance; indeed, Jameson calls them all hornblendes. We have had the pleasure, through the kindness of Mr. Hatchett, of seeing the corundum from Tirie, spoken of by Mr. Jameson, and find it the same sub- stance with these crystals, only much lighter in colour: but, as Mr. Greville observes, they are not fusible, as Kirwan and Jameson ay hornblende is, therefore they can- not be hornblende ; nor are they now supposed to be corun- dum, although the external appearance of the lighter varieties much resembles that substance. We, at present, only men- tion these crystals because they occur in the Tirie marble, but must show larger specimens, and explain them further hereafter. Mr. Jameson in his Mineralogy of Scotland, v. 2. 30. de- scribes the red-coloured marble of Belcphetrich as follows : Colour, pale blood red, light flesh red, and reddish white. Lustre, none, except from a number of dispersed shining foliae. Fracture, fine splintery. Transparency: transmits light freely at the edges. Hardness : yields pretty easily to the knife. X TAB. LXXX. STANNUM oxygenizatum. Oxygenized Tin. Class 3. Metals. Order 1. Homogeneous. Gen. 6. Tito. Spec. 2. Oxygenized Tin, Z>iv. 1. Crystallized. SPEC. CHAR. Combined with oxygen. OCTAEDRAL crystals of oxygenized tin, destitute of any truncations, bevellings, or other modifications, I understand have never been yet found j those here represented are among the nearest known to that simple figure. My friend Mr. Richard Phillips, who possesses one of the finest and earliest collections of tins, &c. from Cornwall, lent me one of his best specimens for this figure, and I am possessed of a similar specimen. They seem in every thing so very like each other, as readily to imply that they came from the same place. They are very black, with much lustre, lying in every direction; some are macled or transposed with various truncations, bevellings, &c. The middle fgure at the bottom shows the most perfect octaedron I have yet seen. The edges of the pyramids are truncated more o 166 or less; the prism is perhaps shorter than here represented. The left-hand outline shows what it should be as a perfect octaedron. The angles of the base of the two pyramids are 90. Those of the face at the summit are 70 31' 44", and at the base 54 44' 8". There have been two opinions concerning the primitive form of oxide of tin: the one, thatit is an octaedron ; and the other, that it is a cube. We have obtained very neat frac- tures parallel to four faces of the latter, and signs of faces inclined upon them, so as to form a rhomboidal dodecae- dron. TAB. LXXXI. GOOD specimens of oxide of tin with the proper four- sided column and corresponding pyramid, if the edges are not bevelled, or truncated, are somewhat rare. Some crystals on the present specimen are of v this form, and others are truncated on the edge of the column, making a fifth face ; which truncation is generally continued up the edge of the pyramid. A four-sided column without truncations, or a pyramid, would be a great curiosity. ft I 167 TAB. LXXXII. i THE figures here represented approach the dodecaedron as nearly as any that I have yet met with of British origin. It will be readily seen that the edges of the four-sided pyramid, as truncated on the left -hand figure, if continued so as to obliterate the octaedral faces, would form, with the help of the four-sided column, eight of the faces of the dodecaedron, the other four faces being hid in the gangue ; and, if with a short column, the faces would be all rhom- boidal ; but if the column be long, the columnar faces will be hexagonal. As yet we have not seen a dodecaedron with both pyramids complete. These specimens are not so black as most, and are modified very roughly. They have also somewhat of a rusty ochraceous hue, probably holding more oxidated iron than usual. We are obliged for this specimen to our friend Mr. Richard Phillips. We have some like it, but much smaller. L C TAB. LXXXIIL SI LEX Quartzum. Agate Pebbles. Class 2. Earths. Order I. Homogeneous. Gen. 4. Silex. Spec. 1. Quartz. Div. 3. Amorphous. SYN. Quartz agathe spheroidal. Haiiy, v. 2. 423. AGATE appears to be a very antient name given to this kind of quartzose stone. It is found on many parts of our shore, as at the Bill of Portland, Lowestoft, and on the Welsh, Scotch, and Irish coasts. It is sometimes found inland, about the lochs in Scotland and Ireland; and, occasionally, in the gravel-pits about London, &c. This species has been much admired for its resemblance to many oriental stones; and differs from our common pebbles by its toughness, which preserves it from large in- ternal flaws. According to its transparency or colour it is more or less valuable, depending on the taste of the owner. Such productions often become pledges of regard, or memo- randums of past hours employed in gathering them; and are thus more esteemed than for their intrinsic value. 170 Exclusive*? these social ideas, they are often equal to the best foreign agates, and bear cutting and polishing equally well. We shall speak of the striped and otherwise marked stones hereafter. The agates found on the sea-coast, being rolled and jum- bled together by the force of the waves, are roughened ; but being hard, this roughness penetrates but a little way, and the utmost force they experience seems only to make little circular flaws ; or, if I may be allowed the expression, more frequently little crescents or semi-circular flaws, from the impulse of the blow coming in a lateral direction. The right hand specimen is from the Bill of Portland. Its outer surface is generally as here represented, but sometimes whiter. The left hand top specimen came from Lowestoft, and was, perhaps, formed by aggregation, as most agate* seem to be (possibly in a trap rock, see Tab. 58), as the cloudy appearance within seems to indicate. The next figure is of a rougher formation. It was sent by the Rev. H. Davies of North Wales. The smooth one on the right hand, with a little red about it, has been called a carnelian. It was found at Lough Neagh in Ireland : but it must be observed that agates, especially British ones, should not be confounded with oriental carnelians, the fracture of the agate not being so shining, and the atone much harder*. The next specimen on the left is a rather pellucid fragment ThU is well known to lapidaries, seal engravers, &c. as it costs them more labour and diamond dust to work them. 171 with the edges partly blunted. The inner figure on the same line was given me by Mrs. Abbot of Bedford, who picked it up in Derbyshire. The smallest of the two lowest ones is ap- parently a fragment, remarkable for the resemblance to part of a septarium ; the inner part resembling the upper right hand figure with a coat of a different colour. The largest figure at the bottom has a resin-like appearance, which these stones occasionally have, and was given me by D. Turner, Esq. who brought it from Ireland. Agates that are found in Scotland resemble all these ; but what are found there, especially near Perth, are admired for being striped, zoned, forming onyxes, or speckled with various blots, &c. resem- bling eyes. Mocoas are a sort of agate with dendrites or figures like sprigs, trees, &c. which seem to be iron, some say manganese, formed in a peculiar manner with the stones, especially the oriental ones, which are durable j but those called German Mocoas by the lapidaries, seem to have had the branching figures introduced by nature or art into their flaws, and such are apt to disappear, often to the great disappointment of the wearer. We digress a little in speak- ing of these, which are foreign subjects, as we do not yet know of any stones worthy to be termed Mocoas found in Great Britain. We consider agate to be nearly of the same nature or a variety of chalcedony. It is said to contain Silex 84, Argil 16. TAB. LXXXIV. PLUMBUM phosphatum. Phosphate of Lead. Class 3. Metals. Order 1. Homogeneous. Gen. 14. Lead. Spec. 3. Phosphate of Lead. Div. 1. Crystallized. SPEC. CHAR. Combined with Phosphoric acid. SYN. Phosphorated Lead ore. Kirw. v. 2. 207. Grun-bleyerz. Emmerl. v. 2. 394. Braun-bleierz. Ibid. 383. Green Lead ore. Syst. Min. Jameson. Plomb phosphatee. ffauy, v. 3. 491. THE yellow phosphates of lead of Wanloch-head mines, Scotland, are found coating Galaena in the Bellan-grain vein, from 20 to 30 fathoms below the surface, but gra- dually disappear at greater depths. From this mine our specimens came by favour of G. Laing, Esq. They are found in other parts of Great Britain besides Scotland, as Wales, Cornwall, Ireland, &c. The purest phosphates seem to be of the brightest yellow, and the crystals are generally very small, being mostly hexaedral columns and their modifica- 174 tions. The present is in very perfect hexaedral columns, and its yellow varies in intensity, with a greenish and brownish cast. The crystals are soft, brittle, easily scraped with a knife, and the powder* corresponds with the colour of the crystal. The crystals will easily scratch carbonate of lead. Fracture splintery and conchoidal. " Integrant molecule an irregular tetraedron. Primitive form a bipyra- midal dodecacdron." Haity. We find these at first, by exposure to the blowpipe, turn green; then they assume a pearly cream colour, and afterwards become irregularly fibrous. The heat being continued, these fibres unite in a somewhat concentrating manner, forming^various polygonal facets in an irregular sort of crystallization : see the left hand Jigure at the bottom. This substance is sometimes situated on an amorphous matrix of its own nature, or on quartz, ochraceous quartz, galaena, &c., as before observed. It is said to be gray by Haiiy, let the colour of the mass be what it will. .V.7 TAB. LXXXV. ST ANNUM oxygcnizatuni. Oxide of Tin, in Crystals zvith S-sided Pyramids, Etain oxyde opposite. Hauy, v. 4. 141. THIS is a rare modification. It is an incomplete 8-sided pyramid placed upon a 4-sided prism, at an angle of 155 according to Rome de 1'Isle, and of 158 45' 27" according to Haiiy. This pyramid is always terminated by another 4- sided one parallel to the octaedron. They either stand on the gangue upright, with one end only finished pyramidally, as appears from the middle figure on the right hand, which is a large and curious detached crystal : being broken at the top, it gives an indication of a point, but on examination we find it cased on an octaedron, which probably it once covered regularly; or they lie on their sides and are pointed at both ends: see the left hand figure. They are seldom large. The gangue is as usual to tin crystals, viz. rock crystal, chlorite, and chlorite schist, or klllas of the Cornish 176 miners. The geometrical outline on the left hand shows the commencement of the 8-sided pyramid on the edge of the prism. There are many varieties of this modification on this specimen, and sometimes of two them meet base to base, and form a mackle : see the bottom figure. I TAB. LXXXVL MANGANESIUM oxygenizatum, var. Primitivum. Oxide of Manganese. Class 3. Metals. Order I. Homogeneous. Gen. 2. Manganese. Spec. 2. Oxide. Diu. 1. Crystallized. Far. 1. Crystal primitive. GEN. CHAR. Spec. Grav. 6.85, somewhat mallea- ble. Colour grayish white, very difficult of fusion, even more so than iron. Colours glass violet. Does not combine with sulphur. SPEC. CHAR. Combined with oxygen. SYN. Manganese mineralized by oxygen, Kirw. v. 2. 291. Gray manganese ore, Syst. Min. Jameson. Braunstein. Emmerl. v. 2. 522. Manganese oxyde. Hauy, v. 4. 243. ]MANGANESE (which was first discovered to be a new me- tal by Bergman), and which has since been found in a na- tive state by Mr. La Perouse, in the valley of Vicdessos, near Sem, in the neighbourhood of Foix, Pyrenees, who 3 178 says it is imbedded in oxide of manganese; is of a silver gray colour with a metallic lustre; divergingly foliated texture, somewhat malleable, and that it soils the fingers. Not knowing of its being found hitherto in Great Britain, we give this short account of it, and shall be glad to be favoured with any specimens which may be met with here- after. We describe with much pleasure the present speci- men of crystallized oxide, as propitious to an expectation that Great Britan nearly includes all that is essential to a knowledge of mineralogy, very few genera being excepted. Mines have been worked in many parts of Great Britain for oxide of manganese. I have some specimens from Mendip Hills in Somersetshire, crystallized in small short rhomboidal prisms. The one figured is crystallized in elongated ones, which have striae on their sides that agree with the fracture. We also find the apex show signs of a diedral or tetraedral summit. The upper right hand figure is nearly the natural appear- ance and size of the specimen; the prisms standing irregu- larly and joining near the base, where they stand upon sul- phate of barytcs, Sec. The gangue is a sort of stratified micaceous grit, through a stratum of .which it runs in veins. In a mass sent me from Aberdeen, the manganese includes crystallized sulphate of barytes, Sec. as trap sometimes docs other stones. The left hand tipper figure is magni- fied, and shows how irregularly the crystals stand on the mass in some parts. Tlie left hand lottom figure shows 179 the upright striae on the prism, and the apex exhibits the diagonal striae, and on some crystals a slight beginning of the two faces which sometimes meet on the centre. The left hand figure shows these striae meeting in four directions to the centre, with the. cross diagonals, giving signs of 4 or more faces. The prism is sometimes truncated so as to form eight sides. Haiiy knew of no other than these eight- sided ones, with 2 or 4 summits at the apex. We first read of short tetraedral prisms of oxide of man- ganese in Catal. de Raab. v. 2. 130, from Naila, in the mar- gravate of Bareith, in Germany, and soon after of rhom- boidal tetraedral prisms, neatly truncated at their extremi- ties, from Ilmenau in Saxony. These of course are in Mr. Greville's matchless collection; we find the latter mentioned, as from Ilfield, inDr.Babington's catalogue of the collection, now belonging to sir John St. Aubin, p. 255. We are glad to be possessed of British specimens from the works near Aberdeen, which I have been given to understand were first discovered by the Rev. Mr. Smith. My friend, Mr. James Reid, among other similar favours, procured me the specimen figured, some time in the year 1803. It agrees exactly with the two last specimens mentioned in Catal. de Raal., in which the word truncated is certainly superfluous, rhomboidal prisms simply, being assuredly meant. This is considered as the primitive form by Haiiy. Oxide of manganese is used in glass-houses in small quantities, to clear and discolour glass by giving up some of 180 its oxygen, and so completing the vitrification of the iron or other colouring ingredients. It is used as a pigment or an ingredient in printer's ink, and to procure oxygen gas from, for many purposes, viz. as a medicine ; or for oxygenizing muriatic acid for bleaching, Sec. About two quarts of this gas may be obtained from an ounce of oxide of manganese. W 7 -' e \ TAB. LXXXVII. FERRUM arseniatum. Arsejiiate of Iron. Class 3. Metals. Ord. 1 . Homogeneous. Gtn* 6. Iron. Spec. 8. Arseniate. D'w. 1. Crystallized. Far. Primitive. SPEC. CHAR. Combined with arsenic acid. SYN. Arseniate of Iron. Bournon in Phil. Trans. 1801. THIS was mostly confounded with arseniate of copper until the celehrated Chenevix, by analysis, ascertained it to be an arseniate of iron : see Phil. Trans, for 1801. Count Bournon observes that it crystallizes in cubes rarely a little flattened : I may add rarely lengthened. I, however, have it a little so, perhaps the fourth of its diameter ; and his figure conveys that idea, although I suppose unintention- ally. The sides, he observes, are smooth and brilliant. I am happy to add another character, that they are diagonally striated in alternate order on each face; this is readily seen in most of my specimens*. They are often a little concave in the centre, and rising to the edges in the longitudinal direction of the striae, and also show signs of being formed on cubical nuclei. I have them from a light yellowish * See Ferrum sulphureum, tab. 63, in which the stria are parallel to the edges of the cube ; and Count Bournon has discovered a new species of cubic oxide of iron with the striae at right angles, parallel to every edge of the cube : perhaps these striz may become marks of importance 182 green to a bright perfect green, apparently neither inclining to yellow or blue, passing on to decpish blue green, and thence to an olive colour, being heightened^ as it were, with red j then, the yellow and red prevailing, they are of a brown- ish resin colour: some are very pellucid and transparent, and all so in some degree. The upper figure shows them of their common natural size in a gangue of quartz mixed with oxides of copper and iron, See. The middle Jigiire is magnified to show their construction more readily; and the right hand geometrical figure shows the striae. In the left hand bottom figure, the only modification known of this substance, according to count Bournon (to use his own words), " Four of the eight solid angles of the cube are re- placed by an equal number of equilateral triangular planes, situated in such a manner that every one of the sides of the cube becomes an elongated hexagon, having two angles of 90 each, and four of 135. Crystals modified in this way are very scarce. I have never seen but one specimen,, which is in the collection of sir John St. Aubin. Its crystals are pretty large and well defined." I therefore consider as a great rarity a specimen in my museum, which exposes two crystals thus truncated. It is easily scratched with a pin, but it scratches common calcareous spar. By Chenevix's analysis it Tvas found to contain Silica - - - 4 Arsenic acid - 31 Oxide of Iron - 45-5 of Copper 9 Water - - - 10-5 100-0 TAB. LXXXVIII. SILEX Quartzum. Flint Pebbles, $c. Class 2. Earths. Order I. Homogeneous. Gen. 4. Silex. Spec. 1. Quartz. Div. 3. Amorphous. SYN. Flint. Kirw. v. 1, 301, Feuer Stein. Emmerl. v. 1. 143. Quartz agathe pyromaque. Haiiy, v. 2. 427, FLINT pebbles, so universally known in the vicinity of London, are not so well known every where, even in Great Britain, since one may travel many miles in some counties without finding any. The forms and colours of common flints are extremely va- rious, and they give strong indications of being formed by in- filtration and aggregation among the softer argillaceous rocks j as the agates, &c. seem to be among the harder rocks of a si- milar natrue; see p. 170: the siliceous infiltration being more or less coloured by oxide of iron, gravitates, or aggregates, into various forms. The upper pebble at the right hand is white at one end, gradually becoming grayer towards the other end, with a 184 line or two of interruption, and at length assuming the colour and texture of common gray flint*. The uncoloured part is sometimes less indurated, but insoluble in acid, and seems only destitute of the colouring matter. The coat appears to have been formed when the process was nearly complete ; as drops of coloured water, or turpentine, will, in general, form a margin in the same manner on substances on which they are put: the others seem formed in a similar way, varying as to regularity. An approach to yellow, with a border of dull crimson, is seen in the next stone, and the coat is nearly black with very little variety. The next right handjigure was given me by a friend who found it near Norwich. It is remarkable for the unifor- mity of the ochraceous tint all through it, and the dark coat penetrating it in the cracks, which seems to confirm the idea of the margin being formed as the substance was beginning to harden. The next stone is very regularly formed. In this, one of the circles is of as true a yellow, and nearly as bright, as I have ever found in flints. The faces of broken flints sometimes become of a brighter yellow when they have been exposed to the air. The upper central one is more irregular, but is in the middle as bright a cinnabar, or vermilion, as can perhaps be found in these sort of stones, und resembles red jasper. The fragment beneath has been * The common ingredients are Siler - 80 Argil - 18 Lime - 2 185 irregularly modified. It is of the brightest crimson in the centre, The Lower left hand figure is uniformly of a red jasper colour, which is not very frequent. Its fracture shows it to be not so tough and hard as jasper. This is rather partially covered with an ochraceous hue. The grey and black flints are not very rare: they are mostly found in wet clayey places, and are often very black, sometimes shining, or blotched with grey or a whitish hue; and, when so, are mostly lighter within under the black outside, and darker under the grey outside* Pebbles, if of a fine ochrey hue, from the size of a horse- bean to that of a Windsor-bean, are used for making foot- ways or walks in our best gardens; and are sold in the vicinity of London from 10 to 12 shillings per load, under the name of gravel; the coarser sort are used to mend the roads*. They are often useful, as at Sandown Castle, near Deal, to defend the coast from the encroaching ocean. They are certainly of more use than they are imagined .to be in agriculturef; and protect the vegetable earth from the violence of the high winds, while they retain the night- * It might be observed that they should not be brought from the damp pits in which they are found to sudden heat or cold, as it makes them rotten, unless intended to be rendered so for manure. f Soil may be amended by the judicious farmer by adding or diminishing their quantity according to what he wishes to cultivate; their composition, size, sponginess, softness, hardness, and even shape, are of much consequence. Q 186 fallen dews and moisture necessary for vegetation. They also defend the roots from the too sudden and scorching heat of the sun in the day. They seem admirably suited for this purpose, as their texture is such as to imbibe heat rather slowly. Thus their being common is a happy providence, and it is very reasonable to suppose that every pebble has its destined use. A great deal more might be mentioned respecting their utility in agriculture; but if what has been said is attended to, it will be found sufficient in this place. We may observe that, when free from flaws and of a good colour, they will bear cutting, engraving, and polishing, as well as the orien- tal carnelians, which they partly resemble in their shining fracture, and almost equal hardness. . iiV TAB. LXXXIX. PLUMBUM carbonatum. Carbonate of Lead. Class 3. Metals. Order 1. Homogeneous. Gen. 13. Lead. Spec. 2. Carbonate. Dlv. 1. Crystallized. SPEC. CHAR. Combined with carbonic acid. SYN. White lead ore. Kirw. v. 2. 203. Jameson, Weisses bleierz. EmmerL v. 2. 388. Mine de plomb blanche. De Lisle, v. 3. 380. Plomb carbonate. Ha'uy, v. 3. 475. CARBONATE of lead has often a great resemblance to car- bonate and sulphate of barytes. It has, however, the advan- tage of weight, is generally more milky in its appearance, and is mostly shorter in the cross fracture; it is also softer. When crystallized, it is more deceptive, assuming the double pyramidal dodecaedron of quartz. It is however most readily to be scratched with a knife, which quartz will not admit of; and when carefully examined, there are very few specimens of this sort that do not indicate a very curious tendency to forming one crystal out of many plated ones. These plates are often so placed that it is difficult to a 2 188 see the modification, especially to an unpractised observer. They often imitate the plated crystals of sulphate of barytes. The present specimen is a very fine one, obtained some years* since. This shows that they sometimes originate from the decomposition of galaena, and they are here yet coloured with it. The matrix is composed of galaena mixed with fluor. This very curious specimen has the first modifica- tion of the quartz -like crystal, deduced from the primi- tive rhomb (see the left hand outline), with the column just visible: these pass into regular dodecaedrons, with very short columns, or rather octo-decaedrons; and also form the *ame figure in plates, which, if regular, show the surfaces of 12 intersecting planes or facets: see the right hand lower figure: but these are seldom quite regular, and they may be so confused and indeterminate that we cannot make them out : see tab. 90. The under jigure is a modification seen on the same specimen, formed by the primitive before spoken of, having a larger deposition on some of the faces than on others, which gives it a lengthened appearance. Analysis by Westrumb : Oxide of lead 81-2 Carbonic acid - 16'0 Lime - - 0'9 Oxide of iron - O'3 Loss - - 1*6 100-0 " 189 TAB. XC. THE specimen here represented would, very naturally, be taken for one of quartz, which it much resembles ; and per- haps it might be passed over by casual observation ag such. It came from the lead hills near Glasgow, and is very valua- ble. It is figured of the natural size, and has part of a. large hexaedral column very distinct, with many eighteen- sided crystals, either like the outline in the middle at the right hand, or like the lower figure at the right hand, with the column interrupted as it were in its formation, giving them the appearance of the buttresses often used in Gothic architecture, and adding many faces to the sides of the crystal, as well as giving additional angles to the faces of the pyramid. They vary much; one is nearly like the left hand lottom Jigure with 1 3 faces, having a pyramid at one end only. TAB. XCI. THIS specimen, lately sent me, by favour of Mr. Laing, from Wanlock Head mines, near Glasgow, shows the dis- position of the last mentioned substance to form plated octo-decaedrons and other modifications, inclining to the appearance of sulphate of barytes, by forming a sort of trun- cation on the edges. Thus the left hand Jigure is truncated 190 on the edges of the original six-sided column, forming six- sided faces : see the dotted lines on the column of the right handjigure, and also the apex which is terminated by six trapezoidal faces. Thus we should have 48 faces if they were regular; this is certainly a curious modification. Mr. Laing judiciously observed, that the sulphuret of lead, or galaena, in most cases, where it is decomposing to form carbonate of lead, has a blue tarnish. It sometimes also becomes dusty or crumbly. TAB. XCIT, SILEX Quartzum, var. aggregatum. Quartzose Pudding Stone. Class 2. Earths. Order 3 . Aggregated. Gen. 2. Silex. Spec. 1. Quartzose. SYN. Pudding Stone. Kirw. v. 1. 360. Bab. 131, Quartz-agathe breche. Hauy 9 v. 4. 461. Poudding. R. De Lisle, v. 2. 481. 1 HIS is not rare, in gravel-pits, in many counties of England ; Hertfordshire is however most famous for pro- ducing it. Pudding Stone is little known abroad, and is therefore esteemed in Germany, and other parts of the continent, as art English rarity. I believe it is not found either in Scotland or Ireland *. The most perfect and most esteemed specimens are those which have the closest and finest siliceous cement, with the greatest number of variegated pebbles, sometimes with fanciful representations : see left hand part of thejigure. They are much the same in texture and hardness through- out, as the flint pebbles figured in tat. 88, and bear a polish equally well with them. The upper figure is one of ihis sort, but is better in some parts than in others. The sides show an imperfection, as * Though in Scotland they call some of the rocks by this name. 192 some of the pebbles are broken out, having been rather moulded than cemented, and almost loose when found. This specimen, I believe, is from Hertfordshire, where some people assert that they grow ! This kind of stone was greatly sought after about a century ago, to be cut into trinkets, snuff-boxes, coatrbuttons, &c. The lower specimen came from South-end, Essex, and was given me by Lady Wilson. The opposite shore, at Sheppy Island, Kent, has many varieties of it, probably washed out of the curious marie clifts of that place. This specimen is somewhat too sandy, and not close-grained enough to bear a polish. They are sometimes found very- large, and I have seen fragments of them that must have been several feet in diameter, which had been formerly worked into querns to grind corn. Probably the name was given by English lapidaries ; and, as Mr. Kirwan observes, they meant, by the appellation of Pudding Stones, to express flint pebbles of any colour ce-r mented with a substance of the same or a similar hardness, so as to make an equally compact stone for polishing, TAB. XCIIL CUPRUM arseniatum. Arseniate of Copper. Class 3. Metals. Order 1. Homogeneous. Gen. g. Copper. Spec. 8. Arseniate. SYN. Bournon. Phil. Trans, for 1802. THIS beautiful specimen of Arseniate of Copper was lent me by my good friend Philip Rashleigh, Esq. of Menabilly. It comes from near Gvvenap. The crystals are spoken of by Count de Bournon as his third variety, tf perfectly regular for a part of their length, and fibrous at their extre- mity/' The present specimen has these crystals with ap- parently four sides of the octaedron, lengthened into fila- ments, and divaricating a little from a centre, forming al- together a sort of brush, narrow at the base, widening towards the apex, and terminating a little abruptly in a sharp or angular point. They are of a dark dull green, somewhat transparent, the ends being generally more opaque and lighter, owing to their fibrous nature : some crystals 194 are of a darker green colour and more confused : see the left handjtgure. The gangue is chiefly quartz, somewhat plated and ochrey> and has intermixed with it bright green arseniate? of copper in irregular granulae : see the right handjlgure. TAB. XCIV. CUPRUM carbonatum. Carbonate of Copper. Class 3. Metals. Order l. Homogeneous, Gen. 9. Copper. Spec. 3. Carbonate. D'w. 2, Imitative. x HE present specimen is a very rare and curious modifi- cation of carbonate of copper. At present I know of only two specimens ; one belonging to P. Rashleigh, Esq., and the other in the possession of Mr. R. Phillips. The upper Jigure, which belongs to the former gentleman, is, as he observes, remarkable for being on the broken end of a large milky rock crystal. The other stands on the crystallized ends of the rock crystal, and is a much larger specimen ; part of it only being figured. This mineral was first considered as an arseniate of copper, but we have every reason to suppose it to be a carbonate. The spiculae are curiously disposed like radii round the edges of a thickish lenticular nucleus. Both specimens are accompanied by a few crystals of each variety of arseniate of copper, figured at tal. 31. ' L r TAB. XCV. BARYTES sulfata. Sulphate of Barytes. Class 2. Earths. Order l. Homogeneous. Gen. 6. Barytes. Spec. 2. Sulphate. Div. 1. Crystallized. THIS curious specimen was sent me from Cumberhead lead mine, at the head of the Nethan river, in Ayr-shire, by G. Laing, Esq. It is remarkable for the crystallized sul- phate of barytes being immersed in amorphous sulphate of barytes. Not having before seen a fracture that indicates the integrant molecule, we are glad to make use of this specimen to show the form of one. It is certainly very rarely to be fractured parallel to all its faces, some of which are not at all to be seen, and it should seem that Haiiy had only observed them by the scintilla- tions within the crystal. To explain the nature of the crystals formed in the upper figure, we have drawn a distinct outline in the middle one, including the nucleus, to show its situation. It will be easily seen that the perpen- ! / 3 198 dicular face at the left hand* end is parallel to the diagonal division of the nucleus, and the oblique fracture is parallel to one of the face* of the rhomboidal prism ; the perpendi- cular lines indicate a continuance of the diagonal fracture, the others a continuation of the rhomboidal fracture. These are extended in the specimen more or less perceptibly until lost in small nuclei, at tl>e right hand end of the crystalli- zation. The third figure may help to familiarise these things by its being placed in another position, and showing similar facts. The lower Jlgure shows the geometrical divisions of the nucleus into two molecules, by means of this fracture parallel to the shortest diagonal of the rhomb. Having seen this, we cannot doubt the opinion of Haiiy y that there may be a fracture parallel to the longer diagonal, dividing the molecules above mentioned into two : thus four upright triangular prisms form the rhomboidal prism or nucleus, each being an integrant molecule. * The faces at this end are all fractured onw. '.-* f~n.<+~r f. TAB. XCVL Div. 2. Imitative. JL HIS variety of sulphate of barytes has obtained the name of cauk among the miners; for what reason I do not know* It has also been called terra ponderosa. The sort here figured is very frequent in Ecton mine, Staffordshire. It is not uncommon in other places, but of a less regular sphae- rical form. It is generally accompanied by carbonate of lime, fluor, galaena, blend, iron and copper pyrites, &c., and is most frequently white. Sometimes it is coloured by oxide of iron, and is then either yellowish, or mostly reddish. The specimen represented in the upper Jigure came from Ecton mine, and is accompanied by calcareous spar and pyrites of various forms and hues. The internal structure is confusedly laminated, showing signs of crystalli- zation, arranged in the form of a sphere; these laminae are extremely close, and often confused, or so thin that no determinate form can be made out, having only the appearance of segments of circular plates, sticking edgewaj by the side of each other : see the bottom Jigure : at other times they are the edges of plates with the faces usual to tabular sulphate of barytes : see tal. 72. The whole are 200 sometimes attached by a greater or smaller base, so as to be nearly detached spheres ; at other times only half a sphere or less. At Bux ton, Derbyshire, however, detached balls are found, not far under the surface of the common earth: see the three Jigures in the middle. They seem to be formed among loam, and partake of an ochraceous hue ; the edges are fre- quently more separated, and less regularly rounded. They have occasionally attached to them single cubic crystals of fluor in a decomposing state ; of which more hereafter. These are somewhat related to the celebrated Bolognian stone, which shines like phosphorus in the dark j and if heated red hot in a common fire, it is said to assume the same property. They are allied also to the liver-stone *, which has its name from its hepatic scent, derived from sulphuret of ammonia or liver of sulphur. Varieties are found in Great Britain, which, when rubbed, give nearly the odour of stink-stone : see tab. 38. Found in Adrarium, in Scania. \ TAB. XCVII. FERRUM arseniatum. Arseniate of Iron. Class 3. Metals. Order I. Homogeneous. Gen. 6. Iron. Spec. 8. Arseniate. Div. 1. Crystallized. Far. 7. Primitive. THIS arseniate of iron is one of the richest that has been seen hitherto; and what adds much to the beauty of the specimen is, that the lighter green cubes are accumulated in groups, forming threads, lying on darker ones, all of which are very pellucid. To add to the rarity of this specimen, we find extremely fine fibres of an oxide of iron? partly encircled by a band as it were of the arseniate, which re- lieves the reddish brown dusty appearance of the oxide; and this last, in return, relieves the glittering arseniate. The fibres of the oxide are so fine that it requires a high magnifier to see them ; we could not discover any other than simple fibres. The top figure is of the natural size; R 202 the middle one, somewhat magnified; tlie lower are more magnified. The gangue is chiefly quartz, with various co- loured ochres and some arsenical iron, or what has been called mispickcl : see the metallic parts in the upper Jigure. This is one of the many fine specimens in Mr. Rashleigh'a collection. I v ~ - -^ ~ TAB. XCVIII. BARYTES sulphata. Sulphate of Barytes. Class 2. Earths. Order I. Homogeneous. Gen. 6. Barytes. Spec. Sulphate. Div. 1. Crystallized. THE specimen from which this figure was taken is in the collection of Mr. Professor Hailstone at Cambridge, to whom it was presented by John Probart, Esq., of Cop- thorne near Shrewsbury, in whose interesting museum the Professor saw several other crystals of the same kind, but of larger dimensions, and understood that they were found in some part of Shropshire; but he had no opportunity of ascertaining any further particulars respecting their native beds, and situation in the earth. It is a valuable specimen, to show the nature of a crystal terminated on all sides, and independent, or not fixed on any gangue. This is not common to sulphate of barytes. It has only a few quartz crystals at the upper corner, as expressed in the figure. The modification is altogether singular, and is a variety not yet figured ; we find it has 23 faces, some scarcely distinct. The crystal is lengthened parallel to the obtuse angles of the rhomb, and the upper primitive face, which shows the prismatic hues somewhat below the surface. It has little hollows as it were unsup- plied by molecules ; this is the case also in other R2 204 giving the crystal a rough appearance. These hollows agree very well, when narrowly examined, with the shape of the nucleus. The general form will be better understood by examining the geometrical figure at the bottom, containing a figure of the primitive or rhomboidal prism : see tab. JO ; allowing for the perspective, and conceiving the sharp angles as the obtuse ones, viz. the right and left hand angles ; the upper and lower faces and the four corners are primitive faces corresponding with the six faces of the nucleus. The four larger octangular faces are evidently parallel to the acute corners of the rhomb (allowing for the perspective). In their formation, the laminae are (as it were) arranged on the upper and under primitive faces, decreasing from the four acute angles of the nucleus from four obtuse angles ; the same also forming 2 long quadrangular faces at the left hand end, and 2 large hexangular ones at the other end of the geometrical figure coming in contact with the primitive faces at the corners, at an angle of about 123 with the upper or under primitive faces. Next to these, on the same angle of the nucleus, are two other 4 -sided faces above and below, the larger at an angle of 140 59' 2" upon the primitive, and the smaller at one of 162 tf 4*". These may be distinctly seen on the top of the upper figure. The Cumberland specimens seem to have the face of 1 23, which appears not to have been seen by Haiiy. Mr. Hailstone's specimen has two small faces marked by dotted lines on the right hand front corner, and one on the right hand corner at the back, which agree with the faces y of Haiiy. This I have not seen in any other English specimen. TAB. XCIX. FERRUM sulphureum. Sulphuret of Iron ; Iron Pyrites. Class 3. Metals. Order l. Homogeneous. Gen. 6. Iron. Spec. 6. Sulphuret. Div. 1. Crystallized. Var. Octaedral, &c. SYN. Fer sulfure octaedre. Hauy, v. 4. 69. OCTAEDRAL Pyrites is not so common as cubical Pyrites ; we have it however along with various substances, as calca- reous spar, limestone, coal, &c. The present figures are designed to show this modification from the cube passing into what Haiiy calls the cubo-octaedre, thence into the perfect octaedron. At the commencement of this change the corners of the cube are replaced by triangular faces see the left hand Jigure which, as the modification goes on, become planes of six sides each see the middle Jigure and at last the primitive faces are lost. These six-sided planes are reduced again to triangular ones, forming the octaedron. I am indebted to the late Lady Elizabeth Noel of Bath for the upper and right hand specimens. The first is the cast of a shell of the Trochus genus ; and it should seem that the crystals are on the cast in place of the shell, as the rock is about the thickness of the shell from the cast, and is a mould of the outside of the shell. On the left hand side remains a bit of the rock, and on the right hand are exhibited the thickness and calcareous remains of the shells, sufficient to indicate the species to a conchologist, which appears to be 6 206 different from any shells of the present age. This is takert from another specimen \vhich also came from Bath by fa- vour of T. Walforu, Esq. The pyrites on this are octae- drons, some of which have their solid angles slightly trun- cated. It nearest resembles Trochus niloticus Linn., but we do not consider it as that species. The cast of the shell on the right hand, of a golden hue, being covered with pyrites, generally deeply truncated, seems a species of Mytilus cut off in the manner of Donax denticulata Linn. The shell on the left hand seems to be a Tellina, and includes pyrites, chiefly of a cubo-octaedral form see left hand bottom Jigure as it were hermetically sealed in, and of course not discovered till the shell was broken. How these crystals came there may excite wonder ; but, were we sufficiently acquainted with nature's operations, we should see every natural cause as well as its effect. This shell most nearly resembles Lister's Tellina lata rvgosa, tab. 390. f. 229. These fossils are in great abundance above the sand quarries at Woolwich and Charlton, about nine feet from the surface of the hill, in a loose marly stratum, from one to six feet thick. How long they have been preserved there is not known ; they however will soon rot and decay after exposure to the air. The other sorts of shells are two species of Turlo, probably of the same date; these will also fall to pieces. Of oyster shells there is great abundance, which do not, to my knowledge, differ from those at present known, nor do they decay so readily as the others. There are other shells in this curious place, and in Lady Wilson's park at Charl- ton, with specimens of which I have been favoured by her ladyship. I have gathered the more common ones myself. 3 TAB. C. CUPRUM oxygenizatum ; var. cubicum. Cubical Red Oxide of Copper. SYN. Cuivre oxyde rouge cubique. Hauy, v. 3. 557. GOOD cubical crystallizations of Red Oxide of Copper are much rarer than octaedrons: see tab. 53. This specimen came from near Redruth in Cornwall. It is crystallized in distinct cubes sometimes, but oftener in rather irregular groups, yet with their edges and planes parallel to each other, seldom like Fluor, tab. 73, or Galsena, tab. 24, &c., which are generally more confused. It rarely forms large cubes, although I understand that some have been found a quarter of an inch in diameter. They are often truncated at their solid angles, forming the cubo- octaedre of Haiiy, t. 63 and 71. The -magnified figure re- presents a group somewhat like one on the specimen, which has a large cubo-octaedre at the left hand corner) and the rest consists of various sized cubes, and one or two of an- other group, showing that the different groups may stand in different directions. 208 These are more generally of a more beautiful Bohemian or Scotch garnet* colour than the octaedrons. We know of no difference in their substances. * Now called Pyrope, differing from the common garnet in colour, trans- parency, and in never being crystallized. It should leem also that they may be ttill further subdivided. SYSTEMATICAL INDEX TO VOL. I. CLASS I. COMBUSTIBLES. Tab. meta&tatica 33 ORDER 1. HOMOGENEOUS - 35 GEN. 7, Carbo Tab. aequiaxi-lenticularis 12 Spec. 2. bituminosus ferrifera-lenticularis 62 Div. 1. crystallized 48 63 Spfc. 3. oiygenizatus Div. 3. amorphous 49 50 Div. a. imitative stalactitica 6 sericea 5 ORDER 2. COMPOUND. coralliformis 9 botryoidea foetida 38 Gen. 1 . Bitumen Div. 3. amorphous Spec. 1. carburetus Div. 3. amorphous 51 cretacea * 7 petrosa 8 79 Gen. 3. Soda Spec. . fluor Spec. 7. muriatum Div. 1. crystallized Div. 2. imitative 22 22 Div. I. crystallized primitiva 26 27 cubica 11 CLASS II. EARTHS. 38-sided 73 ORDER 1. HOMOGENEOUS Gen. 4. Silex Spec. 1 . quarizum Gen. 1. Argilla Spec. 1 , durissima Div. 1. crystallized Gen. 3. Calx 69 Div. 1. crystallized primitivum 41 dodecaedrum 42 Div. 3. amorphous 83 . 88 Spec. 1 . nativa Div. 3. amorphous Spec. 4. sulphata Div. 1. crystallized 1 67 Spec, analcimus Div. 1. crystallized 59 Div. 2. imitative fibrosus 58 Div. 2. imitative pluniosa Spec. 5. carbonata Div. 1. crystallized 68 21 Div. 3. amorphous compactus 57 Spec, granatus Div. 1. crystallized primitivus, &c. 42 pnmitiva 2 3 1"! . . - . 19 Gen. 5. Strontia sequiaxis 2O 13 Spec. 2. carbonata >. 1. crystallized 65 210 SYSTEMATICAL INDEX TO VOL. I. 1 Gen. 6. Barytes Spec. I. ulphata Dn: crystallized ID. Spec. 5. sulphureum Div. 1. crystallized cubical t 1 '.( V primitive &c. 7O 71 octacdral M tabular 72 Spec. 6. sulphatum 95, 96. 98 Div. 2. imitative '_':i Spec. 2. carbonate Dm. 1. crystallized 76 Spec. 9. arseniatum Div. 1. crystallized '-'8 cubical ttc. 07 ORDER 2. MIXED. pig Gen. 10. Cuprum Gen. I. Argilla Spec. 1. nativum Spec. 1. Marga 14 Div. 1. crystallized dodecaedral ts ORDER 3. AGGREGATE. Div. 2. imitative arborescens H Gen. 1. Quartzum Spec. 1. arenaceum 39 4O dendriticum Spec. 2. oxygenizatum Div. 1. crystallized 17 55 octaedrum u Spec. 2. farcimen 92 cubicum l(X) Spec. 3. arenaceum calcareum 15 Spec. 3. carbonatum Div. 2. imitative CLASS 1IL METALS. byssoides radiated 47 Ht ORDER 1. HOMOGENEOUS Spec. 5. sulphureum Div. 1. crystallized Gen. 5. Manganesium tetraedral &c. dodecaedral &c. 77 7f Spec. 1 oxygenizatum Div. 1. crystallized 86 Spec. 8. arseniatum Div. 1. crystallized Gen. 6. Zincum octaedral &c. U Spec. 2. sulphureum Div. 1. crystallized tetraedrum &c. 74 :;i- pi hexangular plate Div. 2. imitative 75 amianthiform a f* ^ M Iren. / otannum Spec. 1. oxygenizatum Div. 1. crystallized 18 pencillatcd Gen. 14. Argentura ;>.5 _____ _ 8O Spec. 1. nativum _______ 81 Div. 2. imitative M 82 Gen. 15. Plumbum Gen. 8. Ferrum Spec. 2, suborygenizatum DID. 1. crystallized 85 54 Spec. 2. phosphate Div. 1. crystallized Spec. 3. sulphureum Div. 1. crystallized 81 Spec. 3. oxygeuizatum Div. 1 . crystallized 66 pn'mitive Gen. 18. Aurum 94 Div. 2. imitative Spec. 1. nativum (foliated) radiatum 64 56 Div. 3. amorphous M 60 ORDER 2. MIXED. fpet. 4. phosphatum crruleum Gen. 1 . Ferrum (oxygenizatum) Da-. 3. amorphous 10 tyec. 1. argiUaceum i-i ALPHABETICAL INDEX OF PLATES, $c. VOL. I. ADAMANTINE spar Tab. 59 57 53 16 69 14 52 76 76 7072. 95, 96. 98 Page. 144 169 1 65 105 128 123. 127 123 125 125 39 37 37 37 33 33 143 33 111 18 157 147. 150 157 147. 150 157 157 157 157 147-150. 1972OO. 203 Agate Air fixed . . Alum Arnphisjene Analcime fibrous in Trap . radie Ardent natif Ar"entum nativurn -var. capi aceum Ar^illa durissima * Aururn nativum , B Barneck Barolite Baryte carbonate sulphata 212 ALPHABETICAL INDEX. Barytes, sulphate of . . . ; 1 /.-. .'.*. .'. tf}-' Tab. 70 72. Page. 147 150. 95,90.98 197-200. 203 14Q Basalt 123 Bath-lime 2 stone 8 18, 10 Bitumen carburetum 51 107 Lithanthrax oo Black-Jack 153 Blei-glanz 55 Blende-khole 103 Blende 153 155 Bley-erz, braun 173 gnm ibid Weisses 187 Bloodstone 122 Blue-John * 55 Borax granatus Ol Bovey coal 1OO Braunstein 177 Building hill stone 82 Burr, French OO C Cachalon OO Calcedony yj OO 1 1 \ Caloric Calx, aerated 5 carbonata , 5 var. aequiaxi-lenticularis . ' - aequiaxis 12 M 29 q 1 * - coralliformis 21 cretacea 7 15 ferrifera lenticularis . lenticularis 62 63 133 134 inversa 33 4 81 - margaritacea . . 45 * ' metastatica 33 3(5 *"5 "''S petrosa 87O 17 163 primitive ' " sericea 3- 20 5 7. 47 1] stalactitica ... . j% "" 13 Calx fluor, var 7J 151 The miners' name for Galana. ALPHABETICAL INDEX. 213 Tab. 11 26, 27 67, 68 21 48 49, 50 49 7 Page. 25 59.61 1 141, 142 49 1 99 103. 105 106. 188 99 103 103 92 131 ibid. 199 52 1. 15 15 5 ibid. 31 133, 134 13 15 7.45 81 5 15 9 7578 7 25 59 25 49 141, 142 26 109 102 ibid, ibid. 104 102 ibid. . primitiva . ' nativa sulphata . . . . var. plumosa Carbo bituminosus oxygenizatus Carbonic acid gas ... Carbon, mineral, impregnated with bi- tumen . . . Carbxincles Cats' heads scalps Cauk Caution against the use of Soda in washing Chalk . . f > common Chaux aeree carbonatee T-. -r- lenticulaire j.. i concretionnee , _ ferrifere _^ fgetjde - formes determinables . . <- grossiere , n> metastatique fluate cubique } primitive fluoree .... sulfate niveforme . trapezienne .... Chlorophane Coal, Bovey Box Cannel . Chesterfield Culm Lynn Newcastle . . 214 ALPHABETICAL INDEX. Coal Peacock Tab. 49 30, 31. 37.93 45,46 94 47 25 17 53 100 69 Page. 104 99 101 102 ibid, ibid. 105 ibid. 104 102 7174. 79- 193 93.95 94 79 195 97 1J5 41 57 41 97 160, 161 115 95 115 ibid, 207 42 159161 ibid. 42 29 146 145 143 146. 164 15 15 87 80 . in upright prisms with rhomboidal bases* Ribband . Scotch Tenby Wigan Copper, arseniate of. ... ^ . p . y .' ~ ~ ' '.' ' \ ' ~ with inclined sides . carbonate of calciform ore, red . arborescent . . . . ore, malachite peacock . ruby wood . oxide of, native ... . octaedral .... plates, for engraving on, &c. . . pvrites . , i i sulphuret of . . . . -, tin, and zinc, make brass Cornu-ammonis Corundum, Ceylon. . } imperfect from China _' j v , r j e Craie compacte Creta Scriptoria Crystal, mountain de roche dodecaedre . . Rhomboidal coal (commonly called dice coal), In contrsdi.linction y> coals which do not break in rhombs. ALPHABETICAL INDEX. 215 Tab. Page. 87 Cuivre arseniate lamelliforme . carbonate vert soyeuse 79 Q7 natif 41 115 ' pyriteux 159, ISO Cuprum arseniatum 30, 31. 71 74. ' copper ore Manganese , an ingredient in printers' ink mineralized by oxygen .... ore, grey . . A f Manganese oxide ... Manganesium oxygenizatnm M^arcassites Marble, red-coloured of Belephetrick . . . Tirie Marga aro"illacea Marie ,. argillaceous . ... . calcareous Marne, la Martial earth, blue Mergel Mocoas Moonstones . Muria montana , N Natrum cristatum Onyxes Or natif P Pebbles, agate s2 220 ALPHABETICAL INDEX. Pebbles flint Tab. 88 Page. 1S8 17 187 ibid. _ phosphate 173 55 99 91 187 "K> Galtna 55 - phosphatuni 84 173 24 55 147 15O Portland stone . . 8 19, 1O Poudding . 1<)1 Puddin? stone . . ibid. ibid pyrites 20 67 69 -_ martial ibid. - martiules ibid. Q ftuartz . 87 80 - . ^athc breche 163 101 183 Hto " irenacee agglut'iDee ivm S3 bti t dodecaedral crystallized 42 HO - hyalin dodecaedre ibid , primitive crystallized 41 87 Quart/urn farcimen 92 101 Quarz * .... 87 Querns . , . . 102 R Roe stone . 18 Rubble s^one 86 Uubellite 144 S 22 51 fibrous 52 sea ,,,.... 51 Salz stein ibid Sandstone 5 110 * Werner's name for quart/. ALPHABETICAL INDEX. 221 Tab. 15 Page. 35 Sandstones, ferruginous liq , siliceous 83 Sarcite* 123 129 Satin spar 5 11 Schlakiges erdpech, variete de 107 Schorle, red 143 Schwer snath . 147 Selenites 142 Sidero-calcite 7 Silber gediegen 37 Silex analcimus , . . . . 5Q 127 C*f 58 IOC Silex Quartzum 83. 88 169. 183 02 1Q1 3O 4O J yi S3 86 55 1 & H9 42 OQ 41 * Silica / ibid. Silver capillary 16 37 fulminating 3Q 37 Smut 100 Soda muriata 22 51 22 52 . muriate of . . 22 51 22 CO 123 Spar calcareous 5 pearl 10 45 147 Spath adamantine d'un rouge violet .... calcaire 144 ^ Spinelle 144 Stalactite 13 ibid Stannum crystallinum 43 , oxy^enizatum ... . 18 0- 43 165'" Staurolite. . , 82. 85 167. 176 138 * Townson's name for analcime. f The common French name for analcime. 322 ALPHABETICAL INDEX. j -