Chemical Composition of Amphibole. 



31 



for study were purposely chosen from quite widely separated 

 regions, and because of their being very unlike in appearance 

 and mode of occurrence. 



I. Tremolite from Richville, near Gouverneur, JVew York. 

 — This locality is the one famous for its brown tourmalines, 

 known to collectors the world over. The specimen consisted 

 of a mass of large white crystals, some showing distinct out- 

 line and. the ordinary forms, m (110), o (010) and r (Oil). 

 When broken up the fine splinters were perfectly transpar- 

 ent. The material used for analysis floated on the heavy solu- 

 tion at 3-002 and sank at 2*992 ; the average specific gravity, 

 therefore, may be taken as 2*997. 



The results of the analyses are as follows — 













Per cents of 





I 



II 



Average 



Ratio 



protoxide bases 



SiO„ 



57-47 



57-43 



57-45 



•957 





Tio; 



















Al 6, 



1-28 



1-32 



1-30 







2 3 



Fe 2 3 



•18 



•18 



•18 



- -014 





FeO 



•22 



•22 



•22 > 





0-3 ) 



MnO 



•07 







•07 





0-1 J-65-2 



MgO 



24-87 



24-83 



24-85 





64-8 J 



CaO 



12-84 



12-94 



12-89 



'•958 



24-0 \ 

 0-7 f-25-8 

 11 ) 



K 2 



•49 



•58 



•54 



Na 2 



•68 



•66 



•67 





H„0 



1 30 



1-20 



1-16 





6-9 



f; . 



•77 





•77 J 





2-1 





100-00 



Loss at ] 



L10° 





•09 









100-19 







= F 2 





•32 







99-87 



The ratios of this and the following analyses will be dis- 

 cussed later. 



II. Tremolite from Lee, Massachusetts. — This material 

 consisted of bladed crystals, showing only prisms, somewhat 

 striated, embedded in a grayish-white, fine-grained, crystalline, 

 dolomite-marble. As far as was observed, the crystals never 

 show distinct terminal faces. The tremolite crystals have a 

 grayish white color, but small fragments are colorless and 

 transparent. The crystals were first carefully selected by hand 

 and after pulverizing and sifting to a uniform grain, the pow- 

 der was treated for a while with warm, dilute hydrochloric 

 acid to insure removal of possible traces of attached dolomite. 



