RE-EXAMINATION OF AMERICAN MINERALS. 151 



The formula Fe S requires sulphur 36.36, iron 63.64=100. 

 Further remarks on this mineral will be found in the paper on 

 meteorites. 



47. Cuban. 



This variety of copper pyrites was first noticed by Breithaupt 

 as occurring among the copper-ores of Cuba. Desiring to re- 

 examine it, specimens were obtained from Prof. Booth; they 

 were massive and not perfectly pure, furnishing an insoluble 

 residue consisting of silica and oxide of iron, which are very 

 probably combined. Its specific gravity was 4.180, and its 

 composition 1 2 3 



Iron 37.10 



Copper 18.23 19.10 19.00 



Sulphur 39.57 39.20 39.30 



Residue (silica and oxide of iron).. 4.23 



99.13 

 This seems to substantiate the formula already received 

 (agreeing with the analysis of Professor Booth), Cu S+Fe 2 S 3 , 

 pyrites being Cu 2 S-f-Fe 2 S 3 = sulphur 42.28, copper 20.82, iron 

 36.90. 



MINERALS OF THE WHEATLEY MINE, PENNSYLVANIA. 



Before describing the minerals of this mine it is well to say 

 a word with reference to its location, and also to quote some 

 remarks on the geology of the surrounding country by Prof. 

 H. D. Eogers. Although this is departing from the plan 

 usually adopted in this series of papers, still the occurrence 

 of all the minerals here described at one locality can not but 

 render the geology of the place interesting to mineralogists. 



This mine is situated in Chester County, near Phcenixville, 

 Pennsylvania, and is one of several interesting developments 

 of a thorough and very able exploration of this region by 

 Mr. Charles M. Wheatley. At the request of Mr. Wheatley, 

 Prof. Eogers made a geological examination of the metalliferous 

 veins of this district, and the following remarks are taken from 

 his report : 



" These veins belong to a group of lead and copper-bearing lodes of a very 

 interesting character, which form a metalliferous zone that ranges in a general 

 east and west direction across the Schuylkill River, near the lower stretches 

 of the Perkiomen and Pickering creeks in Montgomery and Chester counties, 

 and bids fair to constitute at no' distant day a quite productive mineral region. 



