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



present method is based upon antiquated notions dating back to 

 electro-chemical theory of Berzelius. The ideal way would be to 

 record the constituent elements. This can be done with haloids, 

 sulfids, and sulfo-salts but not with the oxygen salts for there is no 

 method of determining oxygen directly. If haloids or sulfids are 

 combined with oxygen salts as in minerals of the apatite group there 

 is decided advantage in recording percentages of the metals and acid 

 radicals. In the silicates the acids and acid radicals are not known 

 and it is necessary to use the ordinary oxids as in rock analyses. 



In recording analyses it is well to give the molecular ratios of 

 elements and acid radicals in addition to the percentage composition 

 even if the purpose is not to establish a chemical formula.^* This 

 plan has been proposed for igneous rocks by Washington^^ but might 

 well be extended to cover minerals. Murgoci^" in an article on the 

 classification of the amphiboles uses a tabulated list of the molecular 

 ratios instead of the more usual percentage compositions. 



My suggestions concerning mineral names are far from carried 

 out at present. Out of Spencer's list^^ of about one hundred new 

 mineral names proposed between the years 1907-10 approximately, 

 not more than fifty-five can possibly be regarded as distinct mineral 

 spaces. That is, forty to fifty names proposed within this short 

 time are, in my opinion, practically useless. There are glendonite, 

 pseudopirrsonite, and pseudostruvite, names for pseudomorphs. 

 Fermorite, anemousite, spandite, and grandite are isomorphous mix- 

 tures. Spandite is an isomorphous mixture of spessartite and 

 andradite, while grandite is an isomorphous mixture of grossularite 

 and andradite. While these names may occasionally be convenient 

 they only increase the difficulty of naming a mineral. The names 

 are not exact for the limits are not defined. Azurmalachite, 

 sefstromite, and leesbergite are mechanical mixtures. Alomite, 



^s The tables in Kemp's " Handbook of Rocks," 5th edition, pp. 171-177, 

 will be found useful in converting percentage compositions into molecular 

 ratios. 



^^ Amer. Jour. Set. (4), Vol. 10, p. 59, 1900. 



20 Bull. Dept. Geol, Univ. of California Pub., Vol. 4, pp. Z77 and 383. 



21 Mineralogical Magazine, Vol. 15, p. 415, 1910. For previous lists see 

 ibid., Vols. II, p. 323; 12, p. 378; 13, p. 363; and 14, p. 394- 



