Volcanism of the Siberian Platform— -Sobolev 
eralogic data, we can be more certain of the 
thermodynamic conditions in and the constitu- 
tion of the upper mantle of the earth, and of the 
conditions of meteorite formation. The forma- 
tion and alteration of diamonds are of particular 
importance in these considerations. There is no 
doubt that further mineralogic investigations in 
general, and the investigation of diamonds in 
particular, will open new approaches to the 
study of the composition of the earth and aid 
in penetrating the secrets of the solar system. 
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