A REVIEW OF THE AMORPHOUS MINERALS 



AUSTIN F. ROGERS 

 Stanford University, California 



Mineralogists generally have neglected the study of naturally 

 occurring amorphous substances. None of the modern miner- 

 alogical textbooks or treatises give an adequate treatment of the 

 amorphous state or condition. Crystals are treated at great length, 

 but the amorphous state is usually given only a paragraph or two. 1 



The reasons for this neglect on the part of mineralogists are 

 apparent. Crystals, with their great variety of form and physical 

 properties, offer a more attractive field for study. Crystalline 

 material so greatly predominates over amorphous material in the 

 earth's outer shell that it is regarded as typical of the solid state. 

 In selecting material for chemical analysis crystals are selected as 

 far as possible, for crystallization is Nature's great method of pro- 

 ducing pure inorganic substances. 



While the mineralogist is primarily a crystallographer and while 

 crystallography is left largely in the hands of the mineralogist, we 

 need to be reminded that mineralogy and crystallography are by 

 no means synonymous. Crystallography deals with crystals pro- 

 duced in the laboratory as well as with mineral crystals. Min- 

 eralogy deals with all homogeneous, naturally occurring, inorganic 

 substances, whether crystalline or amorphous. The two fields 

 overlap but do not coincide. 



In view of the recent advances in colloid chemistry, the mineralo- 

 gist can no longer be excused for his neglect of the study of the 

 amorphous state. Although the science of colloid chemistry has 

 been developed largely by chemists, Breithaupt, one of the early 

 mineralogists and perhaps the greatest of the old natural-history 



1 Knop, however, in his System der Anorganographie (Leipzig, 1876), and Doelter, 

 in his Physikalisch-ehemische Mineralogie ((Leipzig, 1905), both treat the amorphous 

 state at some length. 



SiS 



