Bomite and its Relation to Other Sulpho-Minerals. 553 



can be interpreted as cubic or pseudo-cubic. Heretofore these 

 minerals have been treated chiefly from the standpoint of 

 isomorphism, but unquestionably a new study of the crystallo- 

 graphy of the above groups will show that they are to be con- 

 sidered as morphotropic series, as has been shown for the 

 Fe„S 3 -Cu 2 S series. These relationships will be reported upon 

 in detail later. 



The arrangement of minerals into series of the above charac- 

 ter is, we believe, fully justified not only by what was shown 

 to hold good for the Fe 2 S 3 -Cu 2 S series, but also by the 

 characteristic methods of occurrence and association of the 

 members of these series. This classification* of the sulpho- 

 minerals will undoubtedly be of some service to economic 

 geologists in studying the origin and formation of some ore 

 deposits, for it is reasonable to assume that the members of 

 each series were formed in many instances by the interaction 

 of solutions of the various members, especially of the end 

 members, or by solutions upon the solid phases of some of them. 



Mineralogieal Laboratory, 

 University of Michigan, 

 February, 25, 1914. 



* Somewhat similar classifications are to be found in Tschermak's Minera- 

 logie, 6th edition, 1905, 416-422 ; see also Spencer, Economic Geology, viii, 

 638, 1913, and Clarke's Data of Geochemistry, Bulletin 491, U. S. G. S., 2d 

 Edition, 1911, 623, 628, 630, and 652. 



SCIENTIFIC INTELLIGENCE. 



I. Chemistry and Physics. 



1. The Relative Abundance of Several Metallic Elements. — 

 F. W. Clarke and George Steiger have published the results 

 of analyses of composite samples of several materials in order to 

 show the amounts of some of the minor constituents occurring in 

 the earth's crust. A great many different samples of each kind 

 of material were mixed and the small constituents were deter- 

 mined in large portions of the combined samples. Interesting- 

 data were thus obtained in regard to the percentages of several 

 familiar metals : 



A. "Red clay " of oceanic depths, 51 samples. 



B. Blue and green " terrigenous clays " from oceanic deposits, 

 52 samples. 



C. Mississippi silt, 235 samples. 



D. American igneous rocks, 329 samples.' 



