COLLECTIONS IN ECOXOMrO OEOLOGV AND METALLURGY. 105 



the metal which must bo removed. A slick of ^leeii wood iy [)Iuiij;etl 

 into the b.itli ot" copper, charco.il is thrown on its surface, and tlu' air 

 excluded from the fiunace as much as [)ossil)h}. The final product of 

 this treatment is ingot copi)er, which is ready for use. ( }I3ll,) 



Tiie slag" obtained in this operation is essentially oxide of copper, ami 

 is utilized in the fourth operation. (31312.) 



lu the course of this process copper frequently works its way th^-ough 

 the bottom of the furnace, and three characteristic samples of this aie 

 shown. (31313, 31314, and 31315.) 



THE ORFORD COPPER AND SULPHUR COMPANY. 



These works are located at Bergenport, New Jersey, and treat mainly 

 the sulphide ores of the Crown Mine, Oapelton, Province Quebec, 

 Canada. 



The sulphur of the ores is first utilized for the manufacture of sul- 

 phuric acid and afterwards the copper is extracted by a combined 

 treatment in the blast and rev^erberatory furnaces. 



(1) Sulphide ore, chalcopyrite, pyrite, aud quartz, coutaiuiaif about -10 per cent, 

 sulphur and 4 per ceut. copper. (40220.) 



(2) Roasted or burnt ore, the residue remaining after the sulphur has been burnt 

 off for the manufacture of sulphuric acid. (49347.) 



(3) First matte, obtaiued iu smelting the roasted ore, contains about 30 per cent, 

 copper. (4934H.) 



(4) Slag, x^roduced in smelting for first matte. (49349.) 



(."j) Ground and roasted matte, containing about 3lj per ceut. copper. (49350.) 

 (G) ^Vilite metal, obtaiued by smelting roasted matte. (4935L) 



(7) Blister copper, obtained by smelting white metal. (49352.) 



(8) Ingot copper, obtaiued by refining blister copper. (493.')3.) 



THE BUTTE COPPER DISTRICT. 



Within a very small area near the city of Butte, Silver Bow County, 

 Montana, occurs a group of very remarkable copper mines. The copper 

 occurs in veins, frequently of great width, iu coarse-grained granite. The 

 surface of these veins consisted of quartzose material, with oxides of iron, 

 copper minerals being rare. The}', however, carried considerable silver, 

 and mostof the large copper mines wereoriginallyopenedas silver mines. 

 After reaching the water level, which varies from 50 to 150 feet from 

 the surface, the character of the vein changes entirely, and consists of 

 quartz carrying various sulphides of copper and iron, alone and mixed. 

 These sulphides vary from a nearly pure chalcocite, through borniti', to 

 chalcopyrite, although but small amounts of the latter have been mined, 

 and are frequently associated with pure sulphide of iron, pyrite. 



In some of the mines the principal copper mineral is chalcocite, while 

 in others it is bornite, and this distinction is quite marked. All the 

 ores carry more or less silver, and, especially in the chalcocite mines, 

 free silver i.s found in beautiful sheets on the sulphide of copper. The 

 width of the veins varies, and it is not unusual to find ;>0 feet or more 



