COP

cop

( 523 )

is compofed of fine, pulverulent, cohering, dullparticles. Its fracture is fine grained earthy,paffing occafionally into even and imperfectlyconchoidal. It is opake, (lightly {tains thefingers, and is eafily frangible.

Before the blowpipe it becomes black butdoes not melt. In borax it diffolves with ve-hement ebullition forming a green glafs.

Azure copper occurs in the newer primitiverocks, but more commonly in fioetz mountains.It accompanies other ores of copper, cfpeciallymalachite, grey copper and copper pyrites. Themolt beautiful fpecimens come from the Bannatin Hungary and Siberia . In the Tyrol it isfound in fufficient plenty to be manufacturedinto the pigment called mountain-blue.

Sp. XI. Malachite. Malachit , Werner. Ma-lachite, Brochant. Cuivre carbonate vert, Hauy.

Of this mineral there are the three followingvarieties.

Var. x. Fibrous M. Fafriger M. Werner.

Its common colour is grafs-green palling intoemerald-green and fometimes into dark leek-green. It feldom occurs maffive or difieminated,but generally invefting, and often cryftallizedin fhort capillary needles, difpofed commonlyin divergent bundles or ftars. Externally theyare fhining, but internally only gliftening witha filky luftre. Its fracture is delicate divergingfibrous paffing into coarfe fibrous. It is opakeor tranflucent on the edges, the cryftals are forthe moft part tranflucent. When pulverized itretains its colour, only the tint is fomewhatlighter. It is very foft, brittle and eafily frang-ible. Sp. gr. 3.5. _

It effervefces with acids, and forms a bluecolour with ammonia. Before the blowpipe itblackens and decrepitates, but is infufible per fe.With borax it melts into a green glafs.

Its conftituent parts according to Klaproth ,are 58. Copper,

18. Oxygen,

12.5 Carbonic acid,

11.5 Water

100.0

It occurs ufually in the newer primitive, andfloetz mountains, accompanied by other ores ofcopper, alfo by carbonat of lead, calcareous fpar,brown fpar, and quartz. The fineft fpecimensof this variety of malachite are found in the Si-berian and Hungarian mines: it occurs alfo inSaxony , and various other mining diftricts inGermany, alfo in Norway , in the Mainland,

one of the Shetland iflands, in Cornwall , Derby-fhire, and Ormefhead in Caernarvonfhire.

Var. 2. Compact Malachite. Dicker M,Werner. M. compafle Broch.

Its colour is emerald-green, paffing into grafsand verdigris green; the fame fpecimen exhi-biting different {hades: its external furface iscommonly overfpread with a greeniffi-whitecruft. It occurs maffive, difieminated, andmembranaceous, but moft frequently reniform,cluftered, mamillated, ftalactitic, cellular, orglobular. Externally it is rough and dull, ormarked by black dendrites. Internally it is,according to the kind of fracture, either dull,gliftening or {hining. Its fracture is conchoidalor fine granular uneven, or minutely fibrous.It generally occurs in thin lamellar concentricdiftinct concretions, curved in the fame directionas the furface, each of which has generally adifferent fhade of colour, thus giving to thewhole a fomewhat banded appearance. It isopake, foft, brittle, and eafily frangible. Sp. gr.

3.5 to 3.6.

Its chemical characters and component partsare precifely fimilar to thofe of the precedingvariety, with which it alfo agrees in its geo-gnoftic and geographical fituation. In Englandit occurs at the Lands-end and other places inCornwall , alfo both mamillated and difieminatedin red ochery clay, accompanied by copperpyrites, in fecondary limeftone, at Llanymynech,Montgomeryfhire.

Compadt Malachite, on account of its fineemerald colour, its variable fattiny tiffue andluftre, and the high polifh that it is capable ofreceiving, is an extremely ornamental fubftance,and much fought after on this account. Thelargeft and fineft fpecimen that is known wasprocured in Siberia , and graced the cabinet ofCount Lanlkoi at Peterfburg, after whofe deathit palled into the collection of Dr. Guthrie,where it probably ftill remains. It is a plateabout 35 inches long, 18 broad, and above 2 inthicknefs, and is valued at 800 pounds fterling.

Var. 3. Earthy Malachite. KupfergruttWerner. Vert de Cuivre Broch.

Its principal colour is verdegris-green, pallingfometimes into emerald-green or Iky-blue. Itoccurs in mafs, difieminated, or invefting. In-ternally it is fhining, paffing into gliftening,with a refinous luftre, Its frafture is fmallconchoidal. It is tranflucent and femitranfpa-.rent; is foft and eafily frangible.

Its chief chemical character is that of giving;

little or no effervefcence when diffolved in. acids.