ElvISHA MITCHELIv SCIENTIFIC SOCIETY. 31 



Mountain View mine, Carroll county, Md., and Weed 

 and Pirssont have described the occurrence and form 

 of crystals from the Yellowstone National Park ; but 

 so far as I am able to learn this peculiar occurrence is 

 unique. 



On the Greene place, opposite the home of Mr. K. B. 

 McSwain, near the north-east corner of York county, 

 and about two miles from the King's Mountain battle- 

 field, South Carolina, is a well-marked vein consisting 

 of two bands of iron pyrite about one inch in thickness, 

 with a band of calcareous quartz, from one to three 

 inches in thickness, lying between them. This is the 

 condition of things in the unchanged portion of the vein. 

 Following the vein to the northward and downward, 

 we find the quartz hone^xomed by the leeching out of 

 the calcite, and later the interstices are filled with na- 

 tive sulphur,' that portion of the pyrite lying next the 

 quartz having been changed to iron oxide. I was un- 

 able to find any dikes in the immediate neighborhood, 

 and though the vein was in a portion of its course fold- 

 ed with the schists composing- the countr3^-rock, the 

 folded portions were in most instances entirely un- 

 changed. 



fAm. Jour. Sci., xlii, 401, 1871. 



