108 Native Copper, Ores of Copper, and other Minei^als. 



pounds, have been obtained. The largest mass which has, to my 

 knowledge, been found in New Jersey, is now in the possession 

 of James C. Van Dyke, Esq., of New Brunswick. Its weight is 

 seventy eight pounds ; but a large piece has been detached, and 

 it is said to have weighed, when first obtained, one hundred and 

 twenty eight pounds. It was ploughed up by a farmer near 

 Somerville. On examining this specimen, pure metallic copper 

 is visible in various parts, but with it is intermixed the lead grey 

 oxide, and it is generally incrusted with the green carbonate of 

 copper. There is also associated with these ores an earthy red 

 oxide in the form of a thin crust, and the cavities, which have 

 been formed by the partial decomposition which has taken place 

 on the surface, sometimes contain small quartz crystals. The 

 specific gravity of one of the purest masses of native copper, ta- 

 ken with considerable care, was 7.842 ; but in consequence of 

 the variable proportions of the oxide of copper which they con- 

 tain, scarcely any two specimens give the same results. In three 

 specimens the specific gravity ranged from 7.553 to 7.842. 



A small mass of the purest native copper that I could obtain, 

 was treated with nitric acid. It weighed 14.30 grains, and was 

 entirely dissolved by that agent, with the exception of a iew mi- 

 nute particles, probably silica. The solution was treated with 

 caustic potash, and boiled. The black oxide of copper thus ob- 

 tained, when carefully washed to separate the potash and ignited, 

 weighed 17.95 grains, so that there can be no doubt of the mass 

 having been pure copper. Similar solutions of this mineral were 

 tested for the purpose of ascertaining whether any other metals 

 were combined with the copper ; but none were detected. 



The occurrence of the detached masses of native copper above 

 noticed, is not, however, so interesting as the vein or sheet of this 

 metal which is found in the city of New Brunswick. About fifty 

 rods nearly east of Rutgers College, a thin vein of this kind crosses 

 the red shale, which is here the prevailing rock. It sometimes 

 adheres so closely to the rock as to be with difficulty separated 

 from it. The thickness of the vein is from y'^th to ^th of an 

 inch ; in regard to its extent, no certain information can be ob- 

 tained. It has, however, been traced for several rods ; and I have 

 been informed, that previous to the American revolution, mining 

 operations were carried on here, and that a shaft was sunk which 

 extended for a considerable distance under the bed of the river. 



