MINERALOGY and 

 PETROLOGY' 



In the fields of Mineralogy and Petrology, French 

 scientists have made contributions of inestimable value, 

 and in some parts of these fields they have opened the 

 way and taken a predominant part in the work of de- 

 tailed investigation as well as exploration. 



MINERALOGY 



Knowledge of minerals is based upon a study of them 

 in crystal form; the science of crystals was founded and 

 built in France; as truly stated by Mallard: "Crystal- 

 lography was thus created as a whole by the genius of 

 HAUY, and his successors have scarcely had to do more 

 than perfect the details of his work. No other branch of" 

 human knowledge is, to the same extent, the work of one 

 man." Later, DELAFOSSE and BRAVAIS developed the 

 theory of a mesh or space-lattice of physical units as the 

 structure of crystals a theory completely established, 

 within the past two years, by means of studies with X- 

 rays. FIZEAU and LE CHATELIER made numerous investi- 

 gations of the expansion of crystals upon heating, some of 

 which have had an important bearing upon questions of 

 the condition of formation, especially of quartzose rocks. 



An excellent method of chemical analysis of silicate 

 minerals was early developed by STE.-CLAIRE-DEVILLE. 



1 [Drafting Committee: A. N. WINCHELL, University of Wisconsin. 

 En.] 



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