cop

COP (32 4 )

It is found In Huel Gorland mine in Corn-wall .

Sju XVI. Trihedral Arfeniat of Copper .

Its colour is deep bluifh-green, palling toblack when in a (late of decompofition. Itoccurs cryftallized, in a trihedral prifm, whofebafes are equilateral triangles (which is its pri-mitive form), fometimes one of the edges of theprifm is replaced by a plane parallel to the ad-jacent ones, forming a tetrahedral prifm ; fome-times the plane that replaces the edge of theprifm is confiderably inclined fo as to diminifhand even obliterate one of the bafes, thus form-ing a wedge-fhaped figure with fcalene triangu-lar fides. It alfo occurs in tetrahedral andhexahedral prifms, in very acute rhomboids,and irregular oCtohedrons j alfo capillary andmamillated like the preceding fpecies. Thecryttals are fmall and very fmall, when unalteredare tranfparent'but become opake by decompo-fition. It is fhining, Scratches calcareous fpar,though with difficulty. Sp. gr. 4.28. Its com-ponent parts, according to Chenevix, areOxyd of copper 54Arlenic acid 30

Water . 16

100

Sp. XVII. Martial Arfeniat of Copper.

Its colour is bright fky-blue. It occurs cryf-tallized in a comprefled rhomboidal tetrahedron,terminated at each extremity by a four-fidedpyramid, the faces of which are fcalene triangles.The prifm is fometimes hexahedral, on accountof the obtufe edges of the rhomboid being re-placed by fecondary planes; or odtohedral■when all the four edges are replaced. Thecryflals are very fmall, and are generallygrouped together in fmall fpheres. It is fhining,tranfparent, fomewhat harder than calcareousfpar. Sp. gr. 3.4.

It is compofed, according to Chenevix, ofOxyd of copper 22.5

■- iron 27.5

Arfenic acid 44. e

Water - 1Z .

Silex - 3

98-5

It occurs in Muttrel mine, adjoining to HuelGorland, accompanied by the fame fubftancesas the preceding fpecies.

VII. Family. Phosphat of Copper .

Sp. XVin. Phofphat of Copper .

Its colour externally is greyifh-black, inter-

nally between emerald and verdegris-green. Itoccurs in mafs, diffeminated, and cryftallizedin rhomboids, with convex lateral planes. Thecryftals are fmall and very fmall, their furfaceis drufy, and fhining with a high vitreous luftre.Internally it is gliftening with a filky luftre.Its fraCture is delicate and diverging fibrous.It is opake, and moderately hard. It confifts,according to Klaproth, of

68.13 Oxyd of copper30.94 Phofporic acid

99.08

It has hitherto been found only at Firnebergin Cologne, in white drufy quartz. It was for-merly miftaken for a variety of malachite.

VIII. Family. Muriat of Copper .

Sp. XIX. Sandy Copper . SaltzkupfererzWerner.

Its colour is emerald-green, palling into leekand olive-green. It occurs maffive, diffeminated,and cryftallized in extremely minute fix or four-fided prifms. The furface of the cryftals isfmooth and brilliant, and their fracture lamel-lar. The maffive variety is opake, the cryftalsare tranfparent. It occurs in coarfe and fmallgranular diftinct concretions. It is foft andeafdy frangible. Sp. gr. 4.43.

Before the blowpipe on charcoal it tinges theflame of a bright green and blue colour, and ametallic bead remains behind. It is foluble innitrous acid without effervefcence, and almoftentirely in ammonia. The following are itsconftituent parts according to Prouft and Kla-proth, -

Prouft

Klaproth

,_

/

—*

From Peru

Chili

Chili

7 < 5-595

70.482

73 Oxyd of copper

10.638

. it.446

10.1 Muriatic acid

12.767

18.072

16.9 Water

99.99

IOO.

100.0

It is found loofe in the bed of a river at Re-molinos in Chili, and elfewhere,. though rarely,in Spanifh South America.

Reduction of the Ores.

The redudtion of copper ores in the largeway is on the whole a very fimple bufinefs,being little elfe than a fucceffion of roafting andreducing proceffes of the fimpleft kind, till themetal acquires the defired degree of malleabilityand purity. It is to be obferved that botharfenic and fulphut adhere to copper with great