872 



Fig. 6< Litliiumbisilicate. (chavage-dii'cctions; Fig. 7. Litliiumbisilicate. (Enlarg. 50 times), 

 enlarsement: 50 times). 



Temperature 



in M.V. 

 9920 Little bisilicate; mostly feebly birefringent aggregates of 



tridymite. 

 9930 Idem. 

 10370 Much glass, in w liich imbedded extremely feebly birefringent 



needles. 

 10970 Idem. 

 11570 Idem. 

 11770 Idem. 



Preparation N°. 4. Analysis: 82.17„ SIO^ (=69.4 Mol. Proc). 



Temperature 

 in M.V.: 



9910 Crystalline, principally bisilicate, no tridymile in any appre- 

 ciable quantity. 



9930 Very little bisilicate, many feebly birefringent aggregates; a 

 little glass. 



9970 All glass. 



Preparation W. 5. Analysis: 79.9% Sl(\ (=66.6 Mol. Proc). 



Temperature 

 in if. F. 



9930 Bisilicate in typical form, often nndnlatory extinction, and 

 finely intergrown with needles of impure mefasilicate 

 njr, = J. 56 or 1.57.). 



