COPPEK OKKS. ^93 



compound. A : A=109° 53', and 108° 40'. Cleavage in 

 1 distinct. Also massive, 



and of various imitative 

 shapes. 



Color brass-yellow, 

 often tarnished deep yel- 

 low, and also iridescent. 

 Streak unmetallic, greenish-black, and 

 but little shining. H=3*5 — 4. Gr= 

 4-15— 4-13. 



Composition : sulphur 34 9, copper 

 34 -b, iron 30*5. Fuses before the blowpipe to a globul 

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

 phur fumes on charcoal. With borax affords pure copper 

 The usual effect with nitric acid. 



Dif, This ore resembles native gold, and also iron py- 

 rites. It is distinguished from gold by crumbling when it is 

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

 iron pyrites 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 in granitic and al- 

 lied rocks ; also in graywacke, &c. It is usually associated 

 with iron pyrites, and often with galena, blende, and carbon- 

 ates of copper. 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 Bannat, Hungary, Thuringia, &c. The 

 Cornwall ore is mostly of this kind, and 10 to 12,000 tons 

 of pure copper are smelted annually. The ore for sale at 

 Redruth is said to be by no means a rich ore. It rarely 

 yields 12 per cent, and generally only 7 or 8, and occasion- 

 ally as little as 3 to 4 per cent, of metal. In the latter case 

 such poverty of ore is only made up by its facility of trans- 

 port, the moderate expense of fuel, or the convenience of 

 smelting. Its richness may generally be judged of from the 

 color : if of a fine yellow hue, and yielding readily to the 

 hammer, it is a good ore ; but if hard and pale yellow it con- 

 tains very largely of iron pyrites, and is of poor quality. 



In the United States there are many localities of this ore. 



What forms are preeented by copper pyrites ? What is its color ana 

 streak? its composition? How is it distincruished from iron pyrites and 

 gold ? What is said of the modes of occurrence of this ore and of its 

 mines 1 



