286 J. E. Whitfield — Natural Borates and Borosilicates. 



1. 



Si0 2 49-70 



B a 3 25-80 



CaO 23-26 



Fe 2 3 + Al 2 3 1-02 



Ign. '20 



2. 



48-23 



26-93 



23-24 



•47 



•63 



99-98 99-50 



The comparison of the two analyses shows the material differ- 

 ence to be in the amount of imparities. 



Axinite. — Two specimens of this mineral from different 

 localities were analyzed. The first, from Cornwall, England, 

 was of selected crystals of a dark, clove brown color, translu- 

 cent and implanted on quartz. The second was the axinite 

 from Bourg d'Oisans, Dauphiny, France. This specimen was 

 of a beautiful pearl-gray color, and in some of the smaller crys- 

 tals almost colorless and quite transparent. The third analysis 

 in the series is one of the Dauphiny axinite by Kammelsberg, 

 and is copied from his description of the mineral* for com- 

 parison. 





l. 



2. 



3. 

 Bourg d'Oisans 





Cornwall. 



Bourg d'Oisans. 



Rammelsberg. 



SiO„ . . 



..42-10 



41-53 



43-46 



Al„O n . 



... 17-40 



17-90 



16-33 



Fe n O n . 



...3-06 



3-90 



2-80 



FeO_. 



...5-84 



4-02 



6-78 



CaO .. 



..20-53 



21-66 



20-19 



MnO . 



...4-63 



3-79 



2-62 



MgO . 



...0-66 



0-74 



1-73 



KO_. 





4-62 

 2-16 



•11 



BO.. 



...4-64 



5-61 



H„0 



1-80 



1-45 



100-66 100-32 101-08 



The ratios from the results of analysis No. 2 are: Si0 2 : Al a 8 + 

 Fe 2 O s : (FeO+MnO)+(CaO+MgO) : B 2 3 : H„0— 69 : 20:51 : 6: 



11 40 



12— or 10 : 3 : 8 : 1 : 2— giving B 2 3 . 3R a '"0, . 8R"0 . 2H a O . 

 10SiO 2 , or BR/'R/'H^SiO^O. This expression will allow of 

 the graphic formula : 



■Si(X 



Al— SiO = 



}SiO = }>BO 

 AlfSiO = 



\SiO = 



Al 

 H„ 



R" 



Which gives for the calculated composition considering all the 

 R" as calcium : 



*Zeitschr. d. Geol. G-esellsch., xxi, 689. 



