ELISHA MITCHELL SCIENTIFIC SOCIETY. 8 1 



renthesis are mine.] The observation is very interesting in the light 

 of the recent discoveries. Have we not here at King's Mountain, at 

 or near the junction of these slates and the older gneiss and granite 

 a concentration of this diffused tin ? 



The Cassiterite is mostly massive or semi-crystalline; occasionally 

 crystals are found. Hardness, 6.5 to 7; Specific gravity, 6.6 to 6.9; 

 color, generally dark brown, but varying from this to light yellow 

 and cream-colored, or almost colorless. Composition, mostly an 

 impure Cassiterite, with 50 to 60 per cent, of tin, some dark brown 

 silicious specimens running as low a.s 46 per cent, of tin. The some- 

 what rarer light colored specimens are richer in tin coming nearer 

 the per cent, of metal (78.66) in pure dioxide of tin (SnOa). 



Out of a large number of analyses, I take the following, i retty 

 much at random : 



1. Is a rather light-colored (not the lightest I have seen, however,) 

 yellowish specimen, with a high lustre and distinctly marked cleav- 

 age. 



2. Is a rich brown-colored specimen, not the^ darkest. Analyzed 

 by Prof. G. B. Hanna, U. S. Assay oflSce, Charlotte, for me. 



I. Light-colored, 2. Rich brown-colored. 



Silica 1.76 per cent. 2.36 per cent. 



Arsenic none. . trace. 



Sulphur trace. 0.46 per cent. 



Iron 0.62 per cent. 1.76 " 



Tungstic acid .0.92 " 1. 14 



Tin (by wet method) 74.41 " (by fusion) 65.21 



The tinstone is remarkably free from those worst ingredients of 

 tin ore, sulphur and arsen c. The lower-grade specimens do not 

 show appreciably more than the above, 



TUe accompanying minerals are tourmaline, very abundant ; titanic 

 iron in more immediate relation with the Cassiterite ; lithia mica, 

 generally immediately around the larger lumps of the tinstone in 

 the quartz ; and more rarely zirkon and rutile. 



Raleigh, N. C, February, 1884. 



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