398 BULLETIN 131, UNITED STATES NATIONAL MUSEUM 



been studied in detail because of lack of material and the identifi- 

 cations are tentative. 



CUSTER COUNTY 



A specimen sent to the National Museum for identification from 

 Challis, by Dr. C. L. Kirtley, consists of a rounded nodule of brown 

 jasper invested in a friable granular green layer which appears to be 

 impure chloropal of the variety known as nontronite. 



A specimen from the Reed and Davidson mine, Copper Basin 

 district, is a soft and greenish rock to some extent resembling epidote. 

 This is found, upon microscopic examination, to consist of granular 

 diopside altering to what is probably the nontronite variety of 

 chloropal. The rock contains much magnetite and a little chryso- 

 colla and copper pitch. The chloropal appears under the microscope 

 as confused and felted aggregates of very fine scales of moderately 

 high birefringence which in transmitted light are moderately deep 

 greenish brown in color and show no notable pleochroism. The 

 index of refraction is somewhat variable with a mean of about 

 1.615 ±0.005. 



SHOSHONE COUNTY 



Greenish-brown grains and masses in quartz which contains grains 

 of chalcostibite(?) from the Standard Mammoth mine at Mace are 

 transparent, greenish brown and isotropic to metacolloidal with 

 very fine microcrystalline structure under the microscope. The 

 refractive index is about 1.625 to 1.627. Only a very small amount 

 of the material was available for examination. It was not rare in 

 the mine, however, where it occurred in quartz seams cutting the 

 vein, and plenty of it can probably be found on the waste dump of 

 the Mammoth lower tunnel. It is probably chloropal, but requires 

 more detailed examination on more material. 



HISINGERITE (506) 



Hydrated ferric iron silicate, approximately Amorphous. 



Fe 2 3 .2Si0 2 .4H 2 0. 



Hisingerite is a hydrated iron silicate which closely resembles some 

 forms of limonite, on the one hand, or brown opal and much copper 

 pitch ore. It is probably of rather common occurrence, but has been 

 largely overlooked or mistaken for one of the minerals mentioned. 

 The only place where the mineral has been definitely identified is in 

 the Minnie Moore mine in Blaine County. 



BLAINE COUNTY 



Hisingerite is common in the Minnie Moore mine near Bellevue 

 in the Wood River region, where it was first identified by D. F. 

 Hewett. The material has been subjected to a detailed investiga- 

 tion by Messrs. Hewett and Schaller, whose results will be published. 



