ORES OF COPPER. 133 



mines of Michigan and the Western States ; also at some 

 mines north of Lake Huron ; in the San Juan mining region, 

 Colorado ; north of Gila Biva, near the borders of New 

 Mexico and Arizona ; at the Bruce Mines, Lake Huron, 

 and at Prince's Mine, Spar Island, and on Michipicoton 

 Islands, Lake Superior. 



Covellite, or Blue Copper. A dull blue-black massive mineral, with 

 the composition Cu S. G=3'8. It contains 66-5 per cent, of copper. 



Harridte. A copper glance with cubic cleavage, from Canton Mine, 

 Ga. ; probably a pseudomorph after galenite. 



Chalcopyrite. — Copper Pyrites. Copper-and-Iron Sulphide. 



Dimetric. Crystals tetrahedral or 

 octahedral ; sometimes compound. 

 / A 1= 109° 53 ', and 108° 40'. Cleav- 

 age indistinct. Also massive, and of 

 various imitative shapes. 



Color brass-yellow, often tarnished 

 deep yellow, and also iridescent. 

 Streak unmetallic, greenish black, and 

 but little shining. H. = 3*5-4. G. 

 = 4-15 4-3. 



Composition. CuFe S 2 = Sulphur 

 34-9, copper 34-6, iron 30-5 = 100. Fuses B.B. to a globule 

 which is magnetic, owing to the iron present. Gives sulphur 

 fumes on charcoal. With soda on charcoal affords a glo- 

 bule of metallic iron with copper. The usual effect with 

 nitric acid. 



Biff. This ore resembles native gold, and also pyrite. It 

 is distinguished from gold by crumbling when it is attempted 

 to cut it, instead of separating in slices ; and from pyrite in 

 its deeper yellow color, and in yielding easily to the point of 

 a knife, instead of striking fire with a steel. 



Obs. Copper pyrites occurs in veins intersecting gneiss 

 and other metamorphic rocks ; also in those connected with 

 eruptive rocks ; and sometimes in cavities or veins in ordi- 

 nary stratified rocks. It is usually associated with pyrite, 

 and often with galenite, blende, and copper carbonates. The 

 copper of Fahlun, Sweden, is obtained mostly from this ore, 

 where it occurs with serpentine in gneiss. Other mines of 

 this ore are in the Hartz, near Goslar ; in the Banat, Hun- 



fary, Thuringia, etc. The Cornwall ore is mostly of this 

 ind. As prepared for sale at Redruth it rarely yields 12 



^~ X^cMrr&C 



