112 Native Copper, Ores of Copper, and other Minerals. 



coal it first becomes black, and on increasing the heat, the color 

 changes to red. 



The analysis was performed by subjecting a portion of the 

 powder to a low red heat to expel the water. It was then mixed 

 with about thrice its weight of carbonate of soda, and the whole 

 heated to redness in a platina crucible for upwards of half an 

 hour. The mass was dissolved in dilute muriatic acid, the so- 

 lution evaporated, and the residuum again dissolved in water, 

 slightly acidulated with the same acid, and this solution then fil- 

 tered. The oxide of copper was thrown down by sulphuretted 

 hydrogen, and afterwards, the oxide of iron by ammonia. 



The following is the composition of a specimen of this min- 

 eral from the Schuyler mine : 



"Oxide of copper, - _ _ 42.60 



Silica, - . - . 40.00 



Oxide of iron, - - - 1.40 



Water and loss, - - - 16.00 



100.00 



A specimen from the Bridgewater mine contained thirty seven 

 per cent, of silica. The proportions therefore are subject to va- 

 riation ; and this will account for the discrepancy in the analyses 

 of Bowen, Berthier, and Kobell, noticed by Dr. Thomson in his 

 Mineralogy. 



Gray Sulphuket of Copper. — This ore occurs at the Flem- 

 ington and Nashanic mines. It is massive, sectile, has a dark 

 lead grey color, and is sometimes in the form of roundish grains 

 in the slate rock. All the specimens that I have seen are exceed- 

 ingly impure. The best one gave me the following results : 



Gluartz and silica, - - - 53.25 



Copper, - - - - 38.75 



Sulphur, - - - - 8.00 



Iron, - - - - - trace. 



100.00 



Copper Pyrites, or Yellow Copper Ore. — This mineral 

 occurs massive at the Flemington mine, but I have found it only 

 in very small quantities. It has a brass yellow color, greenish 

 powder, and is a compound of the sulphurets of copper and iron. 



