RE-EXAMINATION OF AMERICAN MINERALS. Ill 



one, and concurring with the one that had been made by us, 

 as well as with those more recently made, which are here given. 



Si A-l 3?e Ca Mg Na K H 



1. 28.47 50.24 1.65 11.50 0.70 1.87 trace 5.00= 99.26 



2. 28.64 51.66 12.25 0.68 2.01* 4.76=100.00 



These correspond to the formula R 3 Si+3£l 2 Si-f 3H. 



Atoms. At. weight. Per cent. Oxygen ratio. 



Silica 4 2309.24 30.58 4 



Alumina 6 3850.8 50.99 6 



Lime 3 1054.5 13.96 1 



"Water 3 337.5 4.47 1 



The specimen of margarite examined was received from 

 Dr. Krantz, of Bonn, and came from Sterzing in the Tyrol, the 

 original locality. 



By these analyses it will be seen that margarite and emery- 

 lite are identical, and the former name having priority of date 

 (although the composition of the mineral was not made out 

 until lately), it must doubtless replace the latter, unless its 

 geological appropriateness can sustain it. 



2. EUPHYLLITE. 



This mineral was first analyzed by Crooke, but the analysis, 

 having been made by a fusion with carbonate of baryta, was 

 found to be incorrect. It was re-analyzed by Erni and Grar- 

 rett.f Dr. Erni's analyses gave the formula R 3 Si+llR Si+3ll. 

 Garrett found no water ; his analyses give the same formula as 

 Erni's, minus the water. 



Our results differ essentially from those heretofore obtained, 

 as is seen by the following analyses : 



12 3 4 



Silica 40.29 39.64 40.21 40.96 



Alumina 43.00 42.40 41.50 41.40 



Peroxide of iron 1.30 1.60 1.50 1.30 



Lime 1.01 1.00 1.88 1.11 



Magnesia 62 .70 .78 .70 



Soda 3.94 3.94 3.25 3.25 



Potash 5.16 5.16 4.26 4.26 



Water 5.00 5.08 5.91 6.23 



100.32 99.52 99.29 99.21 



* By the difference. 



t Amer. Jour. Science and Arts, 2d series, viii, 382; Dana's Mineralogy, 

 3d ed., p. 362. 



