COP

COP

( 321 )

1* a golden yellow, it has a brilliant luftre andan uneven granular, or fmall conchoidal frac-ture ; it is eafily fcratched by iron pyrites, andits fpecific gravity does not exceed 4.1. Cupreousiron pyrites on the contrary cryftallizes in cubesand their modifications, has little luftre, is of abrafs-yellow colour, an uneven fracture, givesplentiful fparks with fteel, and its fpecific gravityis about 5. . The odbahedral figure is commonto both, as being a modification of the tetra-hedron and cube, but the other diftinclive cha-racters are permanent. Of the maflive amor-phous varieties, from which the greater part ofthe manufactured copper is procured, it is pro-bable that the poorer kinds, as molt of the"Welch, are chiefly cupreous iron pyrites, whilethe richer ones of Cornwall are copper pyrites,mixed more or lefs with mifpickel.

Copper pyrites is the moft abundant andgenerally diffufed of all the ores of copper. Itoccurs in veins and beds in primitive, tranfition,and fecondary rocks. In Britain it is foundprincipally in the counties of Cornwall , Derby,Anglefey, and Caernarvon, or in Mainland, oneof the Shetland iflands.

Sp. VIII. Black Copper. Kupjerfchwarze,Werner. Cuivre noir, Brochant.

Its colour is intermediate between bluifh andbrownilh black. It occurs in mafs or diflemi-nated or invefting. It is compofed of dullmoderately cohering earthy particles. It is fri-able, {lightly foils the fingers, is meagre to thefeel, and heavy.

Before the blowpipe it emits a fulphureousodour, and melts into a flag that colours boraxgreen.

It ufually occurs with copper-pyrites, mala-chite, mountain-green and vitreous copper. Itis found in Saxony, Hungary, Silefia, Norway ,and Siberia ; and at Orme’s Head in Caernar-vonfhire in limeftone, accompanied by copper-pyrites, malachite, calcareousfpar and pearl-fpar.

IV. F amily. Arsenicated Copper.

Sp. IX. White Copper. Weifs Kupfererz,Werner. Mine de Cuivre blanche, Brochant.

Its colour is intermediate between filver-whiteand brafs-yellow. It occurs in mafs or diftemi-nated. Internally it has a flight metallic luftre.Its fracture is fmall and fine-grained uneven.It yields eafily to the knife, is brittle and readilyfrangible. Sp. gr. 4.5.

Before the blowpipe it yields a white fmoskwith an arfenical odour, and melts into a greyifhblack flag. According to Henkel it yields 40per cent, of copper, the remainder being iron,arlenic and fulphur,

VOL. U

It occurs in veins and beds in primitive moun-tains, and is generally accompanied by copperpyrites and vitreous copper. It is found in thecopper mines of Cornwall, Saxony , Heffia,Silefia, Hungary, Siberia, and Chili in SouthAmerica .

By its colour and arfenical odour when heated,it is diftinguifhed from the fulphurets of copper;and from arfenical pyrites by its inferior fpecificgravity.

V. Family. Carbonated Copper.

Sp. X. Azure Copper or Mountain-blue.Kupferlazur, Werner. Azur de Cuivre, Broch.Cuivre carbonate bleu, Hauy.

Of this there are the two following varieties.

Var. 1. Radiated A. C. Fefle K. Werner.A. dc C. rayotine, Brochant.

Its principal colour is azure-blue, which paffejinto Pruffian-blue, indigo blue, and rarely tofmalt-blue. It occurs fometimes in mafs, dif-feminated or invefting, more frequently botry-oidal, ftalactitic and cellular, but moft frequentlycryftallized. Its primitive form is that of anoctahedron with fealene triangular faces; butits ufual figures are, an oblique rhomboidalprifm, either fimple or terminated by two oppo-fite triangular facets and dihedral fummits, andan octahedral prifm with dihedral fummits.The cryftals are generally fmall and very fmall,aggregated into, globular or cluftered mafies orbundles. The broad faces of the prifms are■ ftriated in the direction of their breadth, thenarrow faces on the contrary are ftriated length-wife, and all the other furfaces are fmooth.The cryftallized varieties are externally Alining,but the reft are dull. Internally it is Aliningor gliftening with a luftre between vitreous andrefinous. Its fracture is ftrait or diverginglyradiated, rarely lamellar. The cryftals are tranf-lucent and femitranfparent, the other varietiesare opake or at moft tranflucent on the edges.When pulverized it is of a Iky-blue colour. Itis foft, brittle and eafily frangible. Sp. gr. 3.2

to 3.4.

It is very difficult of fufion before the blow-pipe per fe, but with borax it gives a bright-green glafs and a metallic globule.

According to Pelletier it confilts of66 to 70 Copper,

18 — 2o Carbonic acid,

8 — 10 Oxygen,

2 — — Water.

Var. 2. Earthy A. C. Erdige K■ Werner.A. de C. terreux, Brochant.

Its colour is fmalt-blue. It occurs rarely inmafs, generally difleminated or fupevficijl. It2 s