446 SCIENCE PROGRESS. 



Chrysoberyl, Diaspore, and Manganite ; Ludwigite and 

 Pinakiolite ; Olivine, Phenacite, Willemite, Dioptase and 

 Trimerite ; minerals which are generally dispersed among 

 the groups of Oxides or Hydrates, Borates, and Silicates. 



It would be easy to multiply examples, but the above 

 will be sufficient to illustrate the direction in which modern 

 views on mineral species are tending. 



Though veiled, the conflict between Natural-historical 

 and purely Chemical modes of classification still con- 

 tinues ; but it is now mainly a question of interpretation. 

 Mineralogists are pretty well agreed upon the composition, 

 the form, and the other essential characters of crystallised 

 minerals ; they are also agreed upon the futility ol placing 

 such characters as hardness, lustre, colour, etc., in a posi- 

 tion of equal importance with the measurable physical and 

 chemical characteristics. Instead, however, of endeavouring 

 to define each species or to say where it begins and ends, 

 they will be better occupied in studying the variations and 

 ascertaining how the different characters vary together. 

 Sooner or later this will lead to an entire revision of the 

 present system, and probably on the lines indicated in the 

 last paragraphs. 



We may then hope to reduce the complication at 

 present prevailing in the Mineral Kingdom to an orderly 

 variation within certain well-defined and comprehensive 

 groups, each of which may include various chemical types 

 and various crystalline systems, and to understand them as 

 the direct expression of the laws which govern the nature 

 and arrangement of the ultimate particles in crystallisable 

 compounds. 



H. A. Miers. 



