b CALIFORNIA ACADEMY OF SCIENCES. 



prove to be almost perfect dodekahedrons. With fluxes, 

 stroDg chromium reaction. H. above 6. Refraction very 

 strong. Between crossed nicols some grains are isotropic, 

 but the hxrgest number faintly double refracting, some 

 showing an approximate division in sectors. Garnets, as 

 well known, often present abnormal phenomena of double 

 refraction, and, according to Rosenbusch,* the uwarowite 

 always shows these optical anomalies. Uwarowite is 

 known from New Idria, California, occurring on chromite. 

 (See Dana's Mineralogy.) 



A green chromium mineral, also on chromite, from the 

 vicinity of Livermore, Cal., given to me as trautwinite, also 

 proved to be uwarowite, in microcrystalline form. 



Trautwinite t is a mineral associated Avith chromite from 

 Monterey County. In chemical composition it approaches 

 uwarowite somewhat, but differs, according to Gold- 

 smith, in its crystal form, it being hexagonal; it is, more- 

 over, very soft, while uwarowite has a hardness approach- 

 ing 7. 



3. Scorodite. 



At Steamboat Springs, Nevada, in the metamorphic series, 

 metalliferous veins occur with arsenopyrites among other 

 minerals. On this, in cavities and cracks, coatings of a 

 leek green scorodite are found, which, under the microscope, 

 prove to be often perfect crystals with the usual combina- 

 tion of pyramid and pinacoids (111.010.100). Refrac- 

 tion and double refraction very strong. This mineral 

 has recently been found by Professor A. H. Ches- 

 ter, at the Hornsilver miue,| Utah, and as deposit from ar- 

 seniferous thermal waters in the Yellowstone Park, by Mr. 

 A. Hague, g of the U. S. Geological Survey. 



* Microskopische Physiographie der Mineralien, 2d ed., p. 269. 



tE. Goldsmith. Proc. Ac. Philad., 1873. 9.348,365. 



t Am. J. Sc, April, 1887. 



§ Am. J. Sc, September, 1887. 



