610 ROGERS— THE NOMENCLATURE OF MINERALS. [May 14, 



same method can be used with varieties. Thus we can use the 

 term fibrous brucite instead of nemalite. 



Such names as soda-orthoclase, natroalunite, ferrogoslarite, and 

 manganocolumbite are ambiguous. Soda-orthoclase may mean an 

 orthoclase in which a portion of the potassium is replaced by sodium 

 or it may mean the sodium compound corresponding to ortho- 

 clase. The best method is to use a distinctive name for the 

 monoclinic feldspar in which sodium predominates molecularly 

 over potassium. For such a mineral, which has been found 

 at several localities, Schaller^^ has proposed the name barbierite 

 after the French chemist, Barbier. Note the inconsistency in 

 these compound names. Ferrogoslarite is an iron-bearing zinc sul- 

 fate while manganocolumbite is a manganese niobate isomorphous 

 with ferrous niobate. It might be well to restrict these compound 

 names to artificially prepared members of isomorphous series not 

 yet found in nature. Thus we could use the term soda-anor- 

 thite instead of carnegieite. The names silver-analcite, soda-leu- 

 cite, zinc-romerite are examples. 



If my suggestions are adopted a number of mineral names will 

 be discarded. Embolite will be either cerargyrite (chlorargyrite) 

 or bromyrite. Petzite will be auriferous hessite. Pisanite will be 

 either cupriferous melanterite or ferriferous boothite. Hyalophane 

 will be barium-bearing orthoclase. Mesitite will be ferriferous mag- 

 nesite. Nigrine will be ferriferous rutile. 



On the other hand, a few new names or resurrected old names 

 will be necessary. Thus the name montebrasite would be resur- 

 rected for the basic lithium aluminum phosphate which is isomor- 

 phous with amblygonite, lithium aluminum fluo-phosphate. Very 

 few new names will be necessary for synonyms and varieties can 

 often be elevated to the rank of distinct mineral species. 



Some exceptions to my rule should be made. The isomorphous 

 mixtures of three or four common and important mineral groups 

 now have distinctive names which should be retained. Thus we 

 have oligoclase, andesine, labradorite, and bytownite in the plagio- 

 clase group. Olivine is a convenient name for the isomorphous 



^'^ Amer. Jour. Sci. (4), Vol. 30, p. 358, 1910. 



