COP
0 0 P
( 323 )
It has not been analyfed. It is found in fimilarfituations with the other varieties of malachite,but is of much rarer occurrence.
Sp. XII. Emerald Copper . Kupfer-ScbmaragdWerner. Dioptafe Hauy.
Its colour is emerald-green. It occurs cryf-tallized in lengthened dodecahedrons, its primi-tive form being that of an obtufe rhomboid. Itis fhining both externally "and internally, andhas a vitreous luftre. It is tranflucent, paflingto femitranfparent; fcratches glafs feebly andwith difficulty ; is brittle. Sp. gr. 3.3.
Before the blowpipe it becomes of a chefnut-brown colour, and communicates to the flame agreenifh-yellow tinge; it is infufible per fe.With borax it gives a bead of copper, Accor-ding to the analyfis of Vauquelin, it confifts ofOxyd of copper 25.57Carbonat of lime 42.85Silex . • 28.57
9(5.99 _
It has hitherto been found only in Daouria,on the Ruffian and Chinefe frontiers, in a veinaccompanied by malachite.
VI. Family. Arseniat of Copper .
Sp. XIII. 0 £tohedral Arfeniat of Copper .Oktaedrifches Olivenerz Karften.
Its ufual colour is deep fky-blue, palling intoPruffian-blue; it is alfo found of a bright grafs-green, palling into apple-green, greenilh-white,and bluiffi-white. It occurs in obtufe odtohe-drons, formed by two tetrahedral pyramidswith ifofceles triangular planes, united bafe tobafe. The four planes however feldom termi-nate in one point, hence the apex is lengthenedto a ridge, and the bafe, inltead of being a pa-rallelogram, approaches near to a fquare. Thefurfaces are fhining and fmooth, or ftriatedparallel to their edges. The cryftals are im-planted in cavities; they have a,fhining vitreousluftre and a lamellar fracture, are femitranfpa-rent, fometimes tranfparent. Their hardnefs isinferior to that of fluor fpar. Sp. gr. 2.88.
Its conftituent parts, according to Chenevix,are 49 Oxyd of copper14 Arfenic acid3 5 Water
98
It is found in Huel-Gorland mine in Corn-wall , in veins accompanied by vitreous copper,copper pyrites, arfenical pyrites, and iron ochre.
Sp. XlV. Hexahedral Arfeniat of Copper .Blaliriges Olivenerz Karften.
Its colour is deep emerald-green, pafling to
verdegris-green. It occurs cryftallized in thinhexagonal tables. The broad planes are fmoothand brilliant, with a metallic luftre. It is tranf-lucent, fofter than calcareous fpar. Sp. gr. 2.54-
When placed on hot coals it decrepitatesftrongly; its component parts, according toChenevix , are
5 8 Oxyd of copper21 Arfenic acid21 Water
100
It occurs in the fame mine as the precedingfpecies, and is principally accompanied by rubycopper.
Sp. XV. Prifmatic Arfeniat of Copper .Prifinatifches Olivenerz Karften.
Its colour is brownifh, or dark bottle-green,verging fometimes to yellowifh, in which cafeit generally reflects the light of a golden tint,when capillary it is of a lighter and brightercolour. It occurs cryftallized in an irregularacute o&ohedron with a rectangular bafe (whichis its primitive form), or in a long rhomboidalor flattened hexahedral prifm with dihedralfummits, or capillary, either in very lengthenedoftoliedrons or indeterminate. Sometimes thecryftals are regular at one extremity, and ter-minate in capillary brufhes at the other. Thecryftals are fmall, and are accumulated laterallyor implanted. It has a confiderable luftre be-tween vitreous and refinous; is tranflucent,pafling to tranfparent; is harder than flupr, butwill not fcratch glafs. Sp. gr. 4.28.
It pafles into the two following varieties.
1. Amianthiform.
Its colour varies from bluifh-green to grafs-green, brown-green, golden-brown, golden-yel-low, ftraw colour, and white. It occurs inextremely minute parallel or diverging flexiblefibres, or thin dufty flexible lamina;, with moreor lefs of a fattiny luftre.
2. Hematitiform.
Its colour is brownifh or whitifh-yellow. Itoccurs in flat or mamillated layers either fmoothor covered with little rough cryftalline points.Its texture is fibrous, but very compact, refem-bling wood tin.
This fpecies with the Capillary and Hemati-tiform varieties has been analyfed by Mr. Che-nevix, with the following reiult.
Prifmatic. Capillary. Hematitiform.
Oxyd of copper
60.
51
50
Arfenic acid
39*7
29
29
Water . . .
0
18
2r
99-7
98
100
2 S 2