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curved; and the position of the fibres, if parallel or diverging.

in the radiated fracture we are to regard the breadth of the rays, their direction, their position, their passage or cleavage. In the foliated fracture, the size of the folia, their degree of perfection, ther direction, position, aspect of their surface, passage or clearage, and the number of cleavages, are to be noted.

The stape of the fragments may also be very varsalar, as cubic, rhomboida!, trapezoidal, &t. iegular, as cuneiform, splintery, tabular, initely angular.

Arfect of the distinct Concretions.

The shape of the distinct concretions forms very Jasminent external characters. They may be er, different in shape, or in magnitude; by may be lamellar, distinct, concretious, differate direction of the lamelle, in the thick ith regard to shape, and in the position. The surface of the distinct concretions may be Bagh, streaked, or uneven; as for their laste may be determined in the same manner Sernal lustre.

General Aspect as to Transparency. Mer's, as is well known, have different deFf transparency, which may be considered their external characters. They may be , semitransparent, translucent, transthe edges, or opaque.

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External Characters from the Touch.
These are eight in number, and are not destitute
Ayto the mineralogical student.

1. Hard

tem regarded as anomalous; but they seem properly to be classed under this head.

External Characters from the Sound or Hearing. The different kinds of sound which occur in the mineral kingdom are, 1. A ringing sound, as in native arsenic and thin splinters of horn-stone; 2. A grating sound, as in fresh-burnt clay ; 3. A creaking sound, as that of natural amalgam.

2. Friable Minerals.

The external characters drawn from minerals of this class are derived, first, from the external shape, which may be massive, disseminated, thinly coating, spumous, or dendritic: secondly, from the lustre, regarded under its intensity, whether glimmering or dull, and its sort, whether common glimmering or metallic glimmering: thirdly, from the aspect of the particles, as being dusty or scaly: fourthly, from soiling or colouring, as strongly or lightly and lastly, from the friability, which may be loose or cohering,

3. Fluid Minerals.

Of external characters drawn from fluid minerals there are only two kinds, which include three varieties: 1. The lustre, which is either metallic, as iu mercury, or resinous, as in rock oil. 2. The transparency, which is transparent, as in naphtha; turbid, as in mineral oil; or opaque, as in mercury. 3. The fluidity, which may be fluid, as in mercury, or viscid, as in mountain tar.

External Characters from the Smell.

These may be spontaneously emitted and described, as bituminous, faintly sulphureous, or faintly bitter; or they may be produced by breathing on, and yield a clay-like smell; or they may be excited by friction, and smell urinous, sulphureous, garlick-like, or empyreumatic.

External Character from the Taste.

This character prevails chiefly in the saline class, and it contains the following varieties: a sweetish taste, sweetish astringent, styptic, saltly bitter, saltly cooling, alkaline, or urinous.

Having now given a synoptical view of the external characters of minerals, we shall proceed to their classification, and in this we shall chiefly follow the names and arrangement of professor Jameson.

CLASS I

EARTHY FOSSILS.

First Genus. DIAMOND.

Diamond.

This precious stone has great variety of shades, exhibiting a beautiful play of colours. It occurs in indeterminately angular and completely spherical grains, which present planes of crystalliza tion, or are actually crystallized. Its fundamental crystal is the octaedron, which passes into various forms. It is hard in the highest degree, brittle, not very difficultly frangible, and has a spe

2 Temacy; 3. Frangibility; 4. Flexibility; tion to the tongue; 6. Unetuosity; 7. Carness; 8. Weight. Hainess may be tried by a capacity to resist de, yelling a little to it, by being semi-bard, very soft. Tenacity has different degrees, tances being brittle, sectile or mild, or dueThe frangibility consists in minerals being cultly frangible, difficultly frangible, easigible, or very easily frangible. The flexiis proved by being simply flexible, elasticly be, commonly flexible, or inflexible. The cific gravity of 3.600. on to the tongue may be strongly adhesive, rongly, weakly, very weakly, or not at all. y may be meager, rather greasy, greasy, ay peasy. Coldness is subdivided into cold, Put, rather cold. Weight may be distinBased into swimming or supernatant, light, ra. light, heavy, very heavy. The three last difrom the touch are in the Wernerian sys

The diamond has, by modern experiments, been proved to be nearly pure carbon, and begins to burn at 14° or 15° of Wedgewood. See Plate 107. Mineralogy, figs. 1. and 2.

Second Genus. ZIRCON.
First Species. Zircon.
The prevailing colour is grey, but it occurs like-

vise green, blue, red, yellow, and brown, with various intermediate tints.

It is found most commonly in roundish angular pieces, with rounded angles and edges. When crystallized, the figure is generally a rectangular four-sided prism; somewhat flatly acuminated by four planes, set on lateral planes; but of this figure there are several varieties. The crystals are almost always very small, have a smooth surface, bordering on strongly splendent. Internally, the lustre is strongly splendent, passing into adamantine. Fig. 3.

Zircon is hard in a very high degree, brittle, frangible without great difficulty. Specific gravity 4.700. It forms a colourless transparent mass with borax, but is infusible by the blowpipe without ad

dition.

Found in the island of Ceylon, where it was first discovered, and lately in Norway, imbedded in a rock composed of hornblend and felspar,

Frequently cut as a precious stone, and used as an inferior kind of diamond, of which it was once considered as a variety. Its play of colours very considerable.

Second Species. Hyacinth.

The chief colour is red, passing to reddishbrown, and to orange-yellow. The figure a rectangular four-sided prism, flatly acuminated by four planes, which are set in the lateral edges. Of this figure, however, several varieties occur.

The crystals are generally small, and always imbedded. The lateral planes smooth, and externally shining. Internally it is splendent and glassy, inclining somewhat to resinous.

The hyacinth is transparent, very hard, frangible without particular difficulty, feels a little greasy when cut, and has a specific gravity of

about 4.000.

Is fusible with borax. Exposed to the blowpipe it loses its colour, but not its transparency.

Occurs in rocks of the newest floetz trap formation, and sometimes in sand. Is a native of Ceylon, the country of gems; of Spain, of Portugal, France, Italy, Saxony, and probably Scotland.

It takes a fine polish, and when the colours are good, it is highly valued. A third species, called cinnamon stone, has lately been discovered at Columbo, in Ceylon.

Third Genus. FLINT.

First Species. Chrysoberyl.

The prevailing or general colour is asparagusgreen, passing into a variety of allied shades. It exhibits a milk-white light; occurs in roundish and angular grains, which sometimes approach in shape to the cube. It is seldom crystallized; but when in this state it commonly presents a longish six-sided table, having truncated lateral edges, and longitudinally streaked lateral planes. The crystals are small, externally shining, and internally splendent. Fig. 4.

rectangular four-sided prism, with its lateral edges sometimes truncated, sometimes bevilled, and acuminated by six planes. Fig. 5.

The external surface of the crystals is splendent, internally splendent, and vitreous.

It is hard, brittle, not very easily frangible, with a specific gravity of 3.600. Without addition it is

infusible.

Third Species. Olivine.

The colour is generally asparagus-green, of various degrees of intensity. It is found imbedded also in roundish pieces and grains; and when crystallized, which is rare, in rectangular four-sided prisms.

The chrysoberyl is found in Brazil, and in the sand of Ceylon. It is sometimes set in rings with a yellow foil, but is rarely in the possession of our jewellers.

Second Species. Chrysolite.

The chief colour is pistachio-green, of all degrees of intensity. It occurs in original angular sharp-edged pieces, with a rough, scaly, splintery surface, and when crystallized exhibits a broad

Internally, it is shining, varying between glistening and splendent. It is semitransparent, very easy frangible; in a low degree hard, and not particularly heavy. It is nearly infusible without addition. Occurs imbedded in basalt; is frequently found in Bohemia, and also in Hungary Austria, France, England, Ireland, Scotiand, Sweden, Iceland, and Norway. Pieces as large as a man's head have been found in some parts of Germany.

Fourth Species. Augite.

The general colour is blackish-green. It occurs chiefly in indeterminate angular pieces and roundish grains. Occasionally it is crystalized, and presents broad rectangular six-sided pristus. The crystals are mostly small. Interually the lustre is shining, approaching sometimes to splendent.

The augite is only translucent, and but faintly transparent. It is hard, not very easily frangible, and not particularly heavy.

It is found in basalt, either singly or accompanied with olivine, in Bohemia, Hungary; at Arthur's-seat, near Edinburgh; in some of the Hebrides, and in Norway. From olivine it is distinguished by its darker colours, the form of its crystallization, and its greater hardness.

Fifth Species. Vesuviane.

Its principal colour is dark olive-green, passing into other allied shades. It occurs massive, and often crystallized in rectangular four-sided prisms. The crystals are mostly short, and placed on one another. Externally their surface alternates between glistening and splendent. Internally they are glistening, with a lustre between vitreous and

resinous.

The vesuviane is translucent, hard in a moderate degree, and approaching to heavy. Before the blow-pipe it melts without addition.

It is found among the exuviæ of Vesuvius, from whence it derives its name, in Siberia and Kamtschatka. At Naples, it is cut into ring-stones, and sold under various names.

Sixth Species. Leuzite.

The colours are yellowish and greyish-white. It occurs mostly in original round and angular grains. When crystallized, it exhibits acute double eightsided pyramids. Internally it is shining, and approaching to glistening, with a vitreous lustre, inclining somewhat to resinous.

The leuzite is translucent and semitransparent.

It is hard in a low degree, brittle, easily frangible, and not very heavy. It is infusible without addition. With borax, it forms a brownish transparent glass.

It is found in rocks of the newest floetz trap formation, particularly in basalt, near Naples, and in the vicinity of Rome. Bergman gave it the name of white garnet; but Werner has ascertained it to be a distinct species of itself.

[blocks in formation]

The grenatite varies from opaque to translucent, is hard, brittle, easily frangible, and not particular. ly heavy.

It is found imbedded in mica slate, in St. Gothard, Switzerland; and is also met with in Britanny and in Spain.

Eleventh Species. Spinelle.

The predominant colour is red, which passes on into blue, green, yellow, and brown. It occurs in grains, and likewise crystallized in octaedrons with several variations. The crystals are very rarely middle-sized. Externally and internally the lustre is splendent and vitreous.

The spinelle alternates from transparent to vitreous: it is hard in a pretty high degree, and approaches to heavy. It is fusible with borax: occurs in rocks belonging to the newest floetz trap formation; and is found in Pegu and Ceylon. It is used as a precious stone, and considerably valued, though possessing neither the hardness nor the fire of the oriental ruby.

Twelfth Spesies. Sapphire.

The principal colour Berlin blue; but it is found also red, with all the intermediate shades between these two colours. It occurs in small rolled pieces, and crystallized in double three-side pyramids, of which there are several varieties in figure.

The crystals are small and middle-sized. Internally the lustre is splendent and vitreous. It is more or less transparent in different specimens. Some varieties, when cut, exhibit a star of six rays. Fig. 7.

The sapphire is hard in the highest degree, but yields to the diamond; it is easily frangible, and raher heavy, having a specific gravity of about 4.000. It is infusible without addition: occurs in rocks

of the newest floetz trap formation, and is supposed to be an inmate of granite, syenite, and other primitive rocks.

This precious stone is found in the utmost beauty tugal, of France, and of Bohemia. Next to the diain Pegu and Ceylon. It is also a native of Pormond, it is the most valuable of gems, and is used in the finest kind of jewellery.

It should be observed, that the violet-coloured sapphire is the oriental amethyst; that the yellow is the oriental chrysolite and topaz; and that the green is the oriental emerald.

Thirteenth Species. Corundum.

The principal colour is a greenish-white, of various degrees of intensity. It occurs massive, disseminated, in rolled pieces, and crystallized. The crystallizations resemble those of the sapphire, and the crystals are middle-sided and imbedded.

The corundum is duplicating translucent, hard in a high degree, pretty easily frangible, and approaches to heavy. It is supposed to occur imbedded in granite, syenite, or green-stone, and is found in the Carnatic and on the coast of Malabar. See CORUNDUM.

Fourteenth Species. Diamond Spar.

The colour is a dark hair-brown. It occurs massive, disseminated, in rolled pieces, and crystallized in six-sided prisms, or very acute six-sided Pyramids. Internally, its lustre is splendent, approaching in a slight degree to adamantine. may be cut so as to present an opalescent star of six rays, of a peculiar pearly light.

It

It is translucent on the edges, hard in a high degree, easily frangible, and not particularly heavy.

The diamond spar probably occurs in granite. It has hitherto been found only in China. Both this stone and corundum are employed in cutting and polishing hard minerals, and they seem to be nearly allied to each other.

Fifteenth Species. Emery.

Emery is hard in the highest degree, not very easily frangible, and is heavy. It occurs in beds of talc and steatite, and is frequently accomSaxony, in the islands of the Archipelago, in Spain, panied with calespar and blende. It is found in Normandy, and is said also to be a native of the isles of Guernsey and Jersey.

It is of great use in cutting and polishing hard bodies.

Sixteenth Species. Topaz.

The chief colour is a wine-yellow, of all degrees of intensity. It is found massive, disseminated, and sometimes rolled, but most commonly crystallized in oblique eight-sided or four-sided prisms, which exhibit several varieties. The crystals are small and middle-sized, externally splendent; internally splendent, and shining: lustre vitreous.

The topaz alternates from translucent to transparent, and is duplicating transparent. It is hard in a high degree, easily frangiole, and is not particularly heavy. It is fusible with borax; and some kinds in a gentle heat turn white, and are sometimes sold for diamonds.

It is commonly found in veins that traverse primitive rocks in Brazil, Siberia, in Pegu, and Ceylon; in Bohemia, Saxony, and in Cornwall. Exhibiting various forms and tints, it has often been confounded with other precious stones. It is much used in seals and rings.

Seventeenth Species. Emerald.

The green called emerald is the characteristic colour of this species, but it has all degrees of intensity from deep to pale. It is said to occur massive and in rolled pieces, but most commonly cry stallized in low equiangular six-sided prisms. The crystals are middle-sized and small. Internally the lustre is intermediate between shining and splendent, and is vitreous. It alternates from transparent to translucent, and is duplicating transparent.

The emerald is hard, not particularly heavy, melts easily with borax, but is scarcely fusible before the blow-pipe. It occurs in veins that traverse clay-slate, and at present is only found in South America, particularly in Peru, though the Romans are said to have procured it from Egypt and Ethiopia.

From the beauty and vivacity of its colour, the charming emblem of the vegetable kingdom, this precious stone is much admired, and employed in the most expensive kinds of jewellery. See EME

RALD.

Eighteenth Species. Beryl.

This is divided into two sub-species, the precious and the schorlous beryl. See BERYL, and fig. 8.

Nineteenth Species. Schorl.

This is divided into two sub-species, common schorl and tourmaline.

Twentieth Species. Tbumerstone.

The colour is commonly clove-brown, of various degrees of intensity. It is occasionally found massive, more frequently fisseminated; but generally crystallized in very flat and oblique rhombs. Externally, its lustre is generally splendent; internally, it alternates from glistening to shining, and

is vitreous.

This species alternates from perfectly transparent to weakly translucent. It is pretty hard, very easily frangible, and not particularly heavy. It appears to be peculiar to the primitive mountains, and is found imbedded in limestone in Saxony, Dauphiny, Norway, Siberia, and Cornwall.

Twenty-first Species. Iron-Flint.

The colour a yellowish-brown, bordering on liver-brown. It occurs commonly massive, but also crystallized in small equianguiar six-sided prisms. Externally, its lustre is splendent; internally, shining, and is intermediate between vitreous and resinous.

Iron-flint is opaque, and slightly translucent on the edges. It is pretty hard, somewhat difficultly frangible, and approaching to heavy. It occurs in iron-stone veins, and is found in Saxony, and, according to Karsten, at Bristol. It renders the iron ore, along with which it is dug, very difficult

of fusion.

Taventy-second Species. Quartz.

Werner divides this into five sub-species, amethyst, rock crystal (fig. 9.), milk-quartz, common quartz, and prase. The first sub-species is again subdivided into common amethyst and thick fibrous amethyst. See QUARTZ, AMETHYST, &c.

Twenty-third Species. Horn-Stone. Horn-stone is divided into three sub-species, splintery horn-stone, conchoidal horn-stone, and wood-stone.

First Sub-species. Splintery Horn-Stone. The common colour grey, but often red, wi various shades of each. It is usually found ma sive, or in large balls. Internally its lustre is dul but glimmering when it approaches to the natu of quartz. It is more or less translucent on t edges, hard, brittle, very difficultly frangible, ar not particularly heavy.

The substance is infusible without addition; a is found in the shape of balls in lime-stone, an sometimes forming the basis of porphyry. It is native of Bavaria, Sweden, and the Shetland lands; and appears to differ from quartz in co taining a larger proportion of alumina.

Second Sub-species. Conchoidal Horn-Stone. The colour runs from greyish-white to yellowi and greenish-white. It occurs massive. Inte nally, it is a little glistening, strongly transluce on the edges, hard, easily frangible, and not pa ticularly heavy.

Conchoidal horn-stone is found in beds or veins, accompanied with agate, at Goldberg, Saxony.

Third Sub-species. Wood- Stone.

The prevailing colour is ash-grey, but with ma different shades. Its shape is exactly confor able to its former woody form, whether trun branches, or roots. Internally, it is sometim dull, and sometimes glimmering and glistenin slightly translucent on the edges, pretty hai easily frangible, and not particularly heavy.

It is found insulated in sandy loam in Saxon Bohemia, Russia, Hungary, and at Loch Neagh Ireland. It receives a good polish, and is applica

to the same purposes as agate.

Tawenty-fourth Species. Flint.

The general colour is grey, bitt with many : rieties. It occurs massive, in regular plates, in ar gular grains and species, in globular and elliptic rolled pieces, in the form of sand, and tuberose ar perforated. Sometimes it is crystallized, when ite hibits double six-sided prisms, or flat double thre sided pyramids. Internally, the lustre is glin mering, translucent on the edges, hard, easi frangible, and not particularly heavy.

Twenty-fifth Species. Chairedany.

This is divided into two sub-species, chalcedoni and cornelian.

First Shub-species. Common Chalcedony. The most common colour is grey. The extern: shape is various, being massive, in blunt-edge grains and rolled pieces, in original round balls &c. &c. Internally, the chalcedony is almo always dull, commonly semitransparent, hard brittle, rather difficultly frangible, and not par ticularly heavy. It occurs in ampydaloid, and i porphyry; and is found in Trausylvania, in Icc land, Siberia, Cornwall, Scotland, and the H brides. Being susceptible of a fine polish, it is em ployed as an article of jewellery. See CHALCE

DONIUM.

Second Sub-species. Cornelian.

The principal colour is a blood-red, of all degree of intensity. It commonly occurs in roundis pieces, and also in layers : the lustre is glistening bordering on glimmering, and is semitransparent See CORNELIAN, and CHALCEDONIUM.

Agale.

The fossils known under this name are all compound substances; and hence cannot have a particular place in any systematic arrangement. Werner therefore has placed them as a supplement to the species chalcedony, which forms a principal constituent part of them, and disposes them according to their colour-delineations, thus: 1. Fortification agate; 2. Landscape agate; 3. Ribbon agate; 4. Moss agate; 5. Tube agate; 9. Clouded agate; 7. Land agate; 8. Star agate; 9. Fragment agate; 10. Punctuated agate; 11. Petrifaction agate; 12. Coal agate; 13. Jasper agate. They are all compounded of chalcedona, cornelian, jasper, horn-stone, quartz, heliotrope, amethyst, indurated lithomarge, and opal, in different quantities and proportions, and are found in great abundance in Germany, France, England, Scotland, Ireland, and the East Indies.

The uses of agate are various. It is cut into vases, mortars, snuff-boxes, seals, handles to knives, and for many other useful purposes. See AGATE and CHALCEDONIUM.

Twenty-sixth Species. Heliotrope.

The principal colour is intermediate between leek and dark celadon green, or mountain-green. It occurs massive, and in angular as well as rolled pieces. Internally the lustre is glistening, and is always resinous. It is commonly translucent in the edges; is easily frangible, hard, and not particularly heavy.

Heliotrope is found in rocks belonging to the floetz trap formation, in Asia, Persia, Siberia, Saxony, and Iceland.

On account of its beautiful colour and its hardness, it is employed for nearly the same purposes as agate. See HELIOTROPE.

Twenty-seventh Species. Plasma.

The usual colour is intermediate between grass and leek-green, and of different degrees of intensity. It occurs in indeterminably angular pieces, which have a rough earthy crust. Internally its lustre is glistening. It is intermediate between semitransparent and strongly translucent, hard, brittle, frangible without great difficulty, and not particularly heavy.

Hitherto it has only been found among the ruins of Rome, and constituted a part of the ornamental dress of the ancient Romans.

Twenty-eighth Species. Chrysopras.

Its characteristic colour is apple-green, of all degrees of intensity. It is found massive in angular pieces, and in thick plates. Internally it is dull; the lustre intermediate between translucent and semitransparent. It is hard, not very difficultly frangible, nor particularly heavy; and is found along with quartz, opal, chalcedony, &c. at Kosemutcz, in Lower Silesia.

Chrysopras is principally used for ring-stones, and some varieties are highly esteemed; but it is difficult to cut and polish.

Twenty-ninth Species. Flinty Slate. This has been divided into two sub-species, common flinty slate, and Lydian stone.

First Sub-species. Common Flinty Slate. The principal colour is grey, but there are many varieties of shades. It occurs massive in whole beds, and frequently in blunt-angled pieces, with a smooth and glimmering surface. later

nally it is faintly glimmering; more or less trans, lucent on the edges; hard, brittle, difficultly frangible, and not particularly heavy.

It occurs in beds in transitive mountains in

Saxony, at the lead-hills in Scotland, and other places.

Second Sub-species. Lydian Stone.

The colour is greyish-black, passing into velvetblack. It occurs massive, and is frequently found in trapezoidal-shaped rolled pieces. Internally it is glimmering; opaque, hard, pretty easily frangible, and not particularly heavy. It is found in similar formations with the preceding, near Prague and Carlsbad in Bohemia, in Saxony, and in the Moorfoot and Pentland hills, near Edinburgh.

When polished, it is used as a test-stone for determining the purity of gold and silver; but is less suited for this purpose than basalt, and some kind of clay slate.

Thirtieth Species. Cat's Eye.

The principal colour is grey, of which it presents many varieties. It occurs in blunt-edged pieces, in rolled pieces, and likewise massive. Internally it is shining; usually translucent, and sometimes also semi-transparent. It is hard, easily frangible, and not particularly heavy.

Its geognostic situation is unknown. It is imported from Ceylon and the coast of Malabar; and is usually cut for ring-stones. Some of the varieties are highly valued.

Thirty-first Species. Prehnite.

The colours are various shades of green, white, and yellow. It is sometimes massive, and sometimes crystallized in oblique four-sided tables. Externally, the crystals are smooth and shining; internally, inclining to glistening and pearly.

Prehnite is translucent, sometimes passing into semi-transparent and transparent; it is hard, easily frangible, and not very heavy. It occurs in Dau phiny in viens of the oldest formation; in Scotland in rocks belonging to the newest floetz trap forma tion; and was first discovered in Africa by colonel Prehn, from whom it receives its appellation.

Thirty-second Species. Zeolite.

This species is divided by Werner into five subspecies, 1. Mealy zeolite. 2. Fibrous zeolite. 3. Radiated zeolite. 4. Foliated zeolite. 5. Cubec zeolite. As they are principally distinguished from each other by fracture, hardness, and lustre, we shall only observe, that the chief colours of all are yellowish, whitish, and reddish, with a variety of intermediate shades; that zeolite occurs massive, in angular pieces, in balls, and sometimes chrystalized in short and oblique four-sided prisms, and in perfect smooth planed cubes; that it is according to the sub-species opaque, translucent, or even transparent; and that it is semi-hard, easily frangible, and not particularly heavy.

Zeolite occurs in rocks belonging to the newest formation, but is sometimes, though rarely, found in primitive green stone, either disseminated, in cotemporaneous balls, or lining or filling up air cavities or veins. All the different sub-species are natives of Scotland. The mealy zeolite is found in the Isle of Sky; the fibrous and radiated in the isles of Canary and Sky; the foliated in Staffa, and the cubic in the same isle, and likewise in Sky. They are likewise met with in Iceland, in Sweden, in Ger many, and the East Indies.

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