266 BULLETIN 131, UNITED STATES NATIONAL MUSEUM 



ONEIDA COUNTY 



Azurite is reported to have been mined with other copper minerals 

 at the Blackstone mine. 



SHOSHONE COUNTY 



Azurite has been found in moderate amounts in ores of the Horst- 

 Powell (Empire), Handspike, and Riverside mines in the Little 

 North Fork section. Some azurite has also been noted in oxidized 

 lead ore in the Hypotheek mine south of Kingston. Similarly occa- 

 sional specimens have been found in most of the lead mines, especially 

 the Standard-Mammoth, Sierra-Nevada, and Caledonia. It was 

 fairly common in the oxidized ores of the Caledonia mine, occurring 

 usually as stains and impregnations in quartzite. Some specimens 

 show crusts of fine deep blue drusy crystals and others show tabular 

 crystals 5mm. in diameter. Some azurite has also been found in the 

 Snowstorm mine and some of the other copper-bearing veins east of 



Mullan. 



AURICHALCITE (290) 



Basic zinc-copper carbonate, Monoclinic. 



2 (Zn,Cu)C0 3 .3(Zn, Cu)(OH) 2 . 



The basic double carbonate of zinc and copper, aurichalcite, has 

 been seen from a single locality in Idaho, although it probably occurs 

 elsewhere in oxidized zinc and copper-bearing ores. 



CUSTER COUNTY 



The specimen containing the aurichalcite is labeled as being typi- 

 cal ore from three sets above the 450-foot level of the Empire Copper 

 Co.'s mine at Mackay. The aurichalcite occurs as a minutely bladed 

 crust of pale delicate blue color, lining cavities in a dense greenish 

 garnet rock which contains some fluorite. Under the microscope the 

 aurichalcite is seen to form very thin plates which are transparent 

 and pleochroic in tones of pale blue parallel to their elongation and 

 colorless perpendicular to it. The mineral is biaxial, negative with 

 small optical angle. Plates on edge are sky blue in color and have an 

 extinction angle of 41°-42°. The indices of refraction are a= 1.6G0. 

 |8= 1.740, 7=1.745, 7 — a = .085. These optical properties indicate 

 the identity of the material with aurichalcite. Minute blades of 

 calamine are associated with the aurichalcite. 



HYDROMAGNESITE (300) 



Basic hydrous magnesium carbonate. Monoclinic, earth)'. 



4Mg0.3C0 2 .4H 2 0. 



BANNOCK COUNTY 



Hydromagnesite occurs as several deposits within 4 miles of Soda 

 Springs in Bannock County. The mineral forms small disconnected 

 surface deposits, one of which has a surface area of 13 acres, another 



