wherry: sulfide minerals 487 



MINERALOGY. — The nomenclature and classification of sulfide 

 minerals. Edgar T. WhERRY, Washington, D. C.^ 



In a paper published in this Journal over 3 years ago^ the 

 writer put forward a plan for the nomenclature and classification 

 of the native elements, based in a general way upon that fol- 

 lowed in Dana's System of Mineralogy (6th edition), but differ- 

 ing in certain important respects. The fundamental rules of 

 nomenclature are as follows: If only one form of an element 

 is known, the chemical name is used ; polymorphous forms are 

 named by applying crystallographic adjectives to the chemical 

 names; and varieties based on isomorphism are also described 

 by adjectives, constructed by adding the suffix iferous to the 

 names of the elements present in the lesser amounts. The rules for 

 classification are: Two main divisions, non-metals and metals, 

 are recognized, and these are subdivided into groups on a 

 strictly crystallographic basis. For use with minerals composed 

 of two or more elements in combination, this plan obviously 

 requires some modification, and in the present paper a set of 

 rules applicable to the sulfides and related minerals is formulated. 



Nomenclature. — The name first proposed for each mineral is 

 adopted, foreign names being translated or transliterated. The 

 ending ite is added in every case, except where some name with- 

 out such ending is in common use. Separate mineral names are 

 used for polymorphous forms. ^ In minerals in which one ele- 

 ment is clearly essential and others replace it isomorphously, in 

 widely varying but never significant amounts, the plan adopted 

 in the preceding paper is followed: the name of the replacing 

 element, with the suffix iferous, is used as an adjective. On the 

 other hand, in minerals which belong to complete isomorphous 

 series, single names are given to the series, and separate ones to 



^ The data for this paper were assembled while the writer was Assistant Curator 

 of the Division of Mineralogy and Petrology in the U. S. National Museum. Re- 

 ceived July 26, 1920. 



2 This Journal 7: 447-456. 191 7. 



2 The use of Greek-letter prefixes, which has certain advantages, has not been 

 introduced systematically, since it is ordinarily limited to discussions of stability, 

 relationships, etc. 



