LARSEN AND SCHALLER : HINSDALITE 



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mania Tungsten Mine, Washington. The yellow to brownish- 

 yellow mineral is decomposed by acids, yellow oxide of tungsten 

 separating out. 



Analyses of two samples from the same specimen gave : 



The formula deduced is Fe 2 3 . W0 3 . 6H 2 0. 



MINERALOGY — Hinsdalite, a new mineral. E. S. Larsen 

 and W. T. Schaller. Geological Survey? To appear in 

 the American Journal of Science. 



Hinsdalite was first collected (by E. S. L.) from the dump at 

 the mouth of one of the tunnels of the Golden Fleece mine, near 

 Lake City, Hinsdale County, Colorado where it is abundant as 

 an original vein mineral associated with quartz and a little pyrite, 

 galena, tetrahedrite, and barite. It occurs in bands an inch or 

 so across and as crystals imbedded in granular quartz. 



The crystals are either rhombohedrons, resembling cubes, or 

 pseudo-hexagonal tablets. The angle rr' is about 91.3° from 

 which the value 1.268 is calculated for the c axis. If the appar- 

 ent hexagonal base be taken as the true base, there is a per- 

 fect basal cleavage, but the cleavage faces are nearly all wavy and 

 striated. The optical data indicate that the mineral is only 

 pseudo-hexagonal. The hardness is about 5; the luster is vitreous 

 to greasy. The fresh mineral is pale greenish, but much of the 

 material is dark grey from inclusions. The streak is colorless. 



The indices of refraction are somewhat variable but the values 

 for the principal zones are about a = 1.670, /3 = 1.671, 7 = 1.688. 

 Sections normal to the cleavage show parallel extinction, while 

 those parallel to the cleavage are in many cases hexagonal in 



