JOURNAL 



OF THE 



WASHINGTON ACADEMY OF SCIENCES 



Vol. 11 January 4, 1921 No. 1 



MINERALOGY. — .4 new classification of the sulfo-salt minerals. 

 Edgar T. Wherry and William F. Foshag, National 

 Museum.^ 



The data for this paper were collected while the senior author 

 was employed in the National Museum; the junior author, his 

 successor there, has aided in bringing them up to date. The 

 plan followed is essentially the same as that recently applied to 

 the sulfide minerals,- although formulas are stated in both ex- 

 panded and condensed forms, to bring out relationships as fully 

 as possible. The chief new features are: the systematic 

 assignment of minerals to divisions based on the ratios of basic 

 and acidic sulfides, and to groups based on crystallization; the 

 classing of minerals containing both univalent and bivalent 

 metals as double compounds rather than as isomorphous mixtures, 

 and the throwing out of evident admixtures before calculating 

 formulas from analyses; and the interpretation of certain 

 instances of high sulfur content as due to a higher state of oxi- 

 dation of the metal rather than the non-metal, resulting in the 

 discarding of a "sulfarsenate-sulfantimonate" division, such as 

 has usually been recognized heretofore. 



1 Published with the permission of the Secretary of the Smithsonian Institution. 

 Received November 12, 1920. 



2 This JouRNAi, id: 487. 1920. 



