Prof. B. Silliman on some American Minerals. 4-55 



and gave on fusion with carbonate of baryta the following 

 results, viz. quantity taken, 1*378 grni.; found- 

 Oxygen. 

 20'28 = 15 

 23-99 18 



1-54 

 4-08 



This gives the following as the theoretical composition of 

 the mineral : — 



73-97-37 100-00 



The following formulae therefore express its constitution: — 



5Si03, 6Art)3, RO + 3HO=RO, Si03 + 2(3Alt)3, 2Si03) 

 + 3HO. 



The alumina obtained in this analysis (as well as in all the 

 others) was very critically examined for zirconia, but without 

 success. 



The black tourmaline which is associated with euphyllite 

 has left the impression of its crystals on the lateral face of the 

 mineral with such a smooth hard-looking surface that it shows 

 no trace of a micaceous structure. The tourmaline has an 

 uncommon form, the faces 11 of the primary form being rudi- 

 mentary from the extension of the tangential plane, truncating 

 the summit. 



The beautiful foliee of this pearly white mineral have sug- 

 gested the name euphyllite as an appropriate designation for 

 the species, while the name corundellite has the same obvious 

 derivation as enierylite, the mineral described by Dr. Smith. 



There is a similar mineral associated with the blue corun- 

 dum of North Carolina, which was made known to mineralo- 

 gists by the Hon. T. L. Klingman, M.C.,from North Carolina. 

 It occurs investing the corundum. Colour, faint olive-brown. 

 Lustre, vitreous to pearly, like mica. In cleavable plates, 

 apparently hexagonal. Cleavage, perfect ; laminae, separable. 

 Hardness, 3. Gravity, 2-94 to 3*008. Brittle, transparent, 

 not acted on by strong acids. B. B. whitens, gives a brilliant 



