anamination of a few American Minerals. 125 



8. Copper Pyrites, Ellenville, 1ST. Y. 



Mr. Cornwall brought specimens from this locality and 

 analysed one in my laboratory. 



The mineral was associated with galena, blende, and quartz. 

 0-985 grms. were treated with boiling aqua regia, leaving 

 0-002 grms. = 0.203 per cent silica. All the sulphur was 

 oxidized and precipitated as sulphate of baryta ; the sulphate 

 weighed 2-631 grms. = 0-361 grms. or 36*649 of sulphur. The 

 copper and lead were precipitated by sulphuretted hydrogen, 

 and the sulphides dissolved in nitric acid. The lead was sepa- 

 rated from the copper by evaporating to dryness with sulphuric 

 acid and washing out the sulphate of eopper with water. 

 Found sulphate of lead 0-005 grms. = 0-003 grms. or 0.301 per 

 cent. lead. 



The copper was determined from a fresh portion after sepa- 

 rating the lead, iron, and silica, by precipitating with caustic 

 potassa. 0.481 grms. of the ore were taken ; found, oxide of 

 copper 0-196=32-432 per cent. , 



The iron was precipitated by ammonia, and weighed as ses- 

 quioxide — from 0-800 grms. of the ore — found 0*358 grms. 

 = 31*25 per cent. iron. 



Results of the analysis. 



100*838 



99*240 



New York, May 1, 1865. 



