Washington — Suggestion for Mineral Nomenclature. 151 



Datolite Group. 



Datolates, R" 8 R'" 9 Si 2 O 10 , monoclirric. 



Datolite, H 2 Ca 2 B 2 Si 2 O 10 Acid calcium bori-datolate 



Euclase, H 2 Gl 2 Al 2 8i 2 O in Acid glucinum alumi-datolate 



Gadolinite, FeGl 2 Y 2 Si 2 O 10 Ferro glucinum yttri-datolate 



Homilite, FeCa 2 B 2 Si 2 :o Ferro calcium bori-datolate 



Spinel Group. 

 Sjrinelates, R // R'" 2 4 , isometric. 



Spinel, MgAl 2 4 Magnesium alumispinelate 



Hercynite, FeAl 2 4 Ferrous alumispinelate 



Gahnite, ZnAl 2 4 Zinc alumispinelate 



Magnetite, FeFe 2 4 Ferrous ferrispinelate 



Chromite, FeCr 2 4 Ferrous chromispinelate 



Apatite Group. 

 Apatates, R" 5 (F, 01) ((P, As, Y)0 4 ) 3 , hexagonal. 



Apatite, Ca 6 (F,Cl)(P0 4 ) 3 Calcium phosphapatate 



Pyromorphite, Pb 5 Cl(PU 4 ) 3 Lead phosphapatate 



Mimetite, Pb 5 Cl(As0 4 ) 3 Lead arsenapatate 



Svabite, Ca 5 F(As0 4 ) 3 Calcium arsenapatate 



Yanadinite, Pb 5 Cl(Y0 4 ) 3 Lead vanadapatate 



Locust, N. J., November, 1911. 



