380 Prof. B. Sillvman^ Jr., on some American Minerals. 



It is obvious that this is very nearly the true constitution of 

 the mineral ; the following formula corresponds very closely with 

 the analytical results, viz. : 



tt* 



4*4 * • ■ « * ff 



R 3 Si* Al°+H° = (CaNa]VIg) 3 Si+3A12 Si+3H. 



4 atoms silica = 2309*24 = pr. ct. 3051 



6 « alumina 385400 50 92 



3 " lime 106806 14-11 



3 « water 33744 446 



756874 10000 



This result leaves but little doubt that the mineral here examin- 

 ed is the same as the Turkish Emerylite. That the American spe- 

 cies will be found constant in containing water 1 have no doubt. 



Great care was bestowed on the trials to detect zirconia, but 

 none was found. 



Corundellite. 



S llJ 5 



Corn 



dellite. This species in external characters much resembles the 

 last, but its composition is different in important particulars. It 

 is also found associated with the corundum and emery of Union- 

 ville, Chester Co., Pa. The specimen here analyzed is marked 

 " D," and was taken by me in May last, from the mineral collection 

 of the Chester Co. Cabinet, formed by Mr. Williams. It is in broad 

 foliated masses of a yellowish white color, easily cleavable and 

 apparently hexagonal in form, penetrated by hexagonal crystals 

 of corundum. Inelastic, brittle, resembles common mica but not 

 so strikingly as A. Hardness 35. Gravity 3. B. B. gives the 

 same characters as the last species. No reaction could be obtain- 

 ed for lithia or boracic acid in any of the minerals of this series. 

 The reaction for fluorine in this one was feeble. It is unaffected 

 by strong acids even on long boiling, except partially by very 

 strong sulphuric acid. Its qualitative analysis gave silica, alumina, 

 lime, potash, soda and water, with a trace of iron and fluorine. 



The following analysis was made by Mr. J. J. Crooke, on 1-389 

 gramme of the substance fused with carbonate of baryta. It 

 yielded 



Oxvgen. 



Si -496 m per cent. 35708 = 18 : 553 = 18-55= 9 



Al -738 53 131 24872 24 87 12 



Ca -101 7-271 2042 



K 017 1-224 0-207 J- 2 36 1 



Na 006 0-413 0110 



HandFl-032 2 303 2 050 2 05 1 



1-390 100068 



