378 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



sectrix normal to the perfect cleavage. Individual scales are too 

 small to 3^ield an interference figure in convergent light. The optical 

 character is positive, the indices of refraction as determined by 

 immersion being: 



a= 1.582 ±.003 



/J=1.582±.003 



7=1.593±.003 



a-7= .011 ±.003 



CHROMIUM-BEARING CHLORITE FROM WYOMING. 



Several specimens recently received at the United States Na- 

 tional Museum by transfer from the United States Geological Survey 

 consist of granular chromite containing veins and disseminated 

 crystals of a deep purplish red chlorite. The locality from which 

 these specimens were obtained is given as Deer Park, Wyoming. In- 

 dividual crystals of the chlorite reach a maximum diameter of 1 

 cm. and are somewhat crumpled as from pressure. Aside from the 

 chromite which makes up the bulk of the specimens, the only asso- 

 ciated mineral is a brilliant green clayey substance which lines 

 cavities in the specimens. This mineral, which is doubtless wol- 

 chonskoite, is not present in sufficient amount for analysis. 



By careful hand picking the chloritic mineral was obtained for 

 analysis free from all but a very little chromite, which under the 

 microscope was seen to occur as minute grains between the folia 

 of the chlorite itself. Upon analysis of this selected material the 

 following results were obtained: 



Analysis of chromiuia-bearing chlorite from Wyoming, 



This analysis yields the following ratios: 



Ratios of chlorite from Wyoming. 



