264 BULLETIN 131, UNITED STATES NATIONAL MUSEUM 



all of the oxidized lead-silver deposits associated with cerusite, 

 having been noted in the upper levels of the Mammoth, Last-Chance, 

 Hercules, and other lead mines. Radial bunches and small mam- 

 millary masses occurred in oxidized lead ore in the Sierra Nevada 

 mine in Deadwood Gulch and in the lead-copper ore of the Cale- 

 donia mine. In the latter mine, which produced more malachite 

 than any other lead mine in the district, much of the malachite 

 formed a green impregnation in quartzite surrounding other copper 

 minerals. Fibrous or mammilla^ green forms occurred with ceru- 

 site and cuprite and delicate acicular crystals were found in spongy 

 masses of limonite. Occasionally pearly crystals of cerusite were 

 stained a delicate green by a thin outer layer of malachite. 



Some beautiful little specimens showing radiating acicular prisms 

 of malachite embedded in soft limonite have been obtained from the 

 Horst-Powell (Empire) and Handspike mines on the Little North 

 Fork of Coeur d'Alene River. Specimens showing radial and small 

 mammillary masses of malachite in limonite-silica skeletons and 

 others having radiating green needles in cavities in quartz have been 

 seen from the Hypotheek mine on French Gulch, 3 miles south of 



Kingston. 



AZURITE (289) 



Basic copper carbonate, 3Cu0.2C0 2 .H 2 0. Monoclinic. 



The fine blue copper carbonate, azurite, occurs commonly with the 

 related green carbonate malachite as stains, incrustations, and deep 

 blue crystals where primary copper sulphides have been subjected 

 to oxidation. The mineral is almost coextensive in distribution with 

 malachite as the two are almost invariably formed together. Azu- 

 rite is a little less common or abundant than malachite, however, 

 since malachite is the more stable compound and azurite tends to 

 change to malachite. 



ADAMS COUNTY 



In Adams County azurite is common as blue stains and incrusta- 

 tions in many of the copper mines of the Seven Devils district, but 

 it is nowhere very abundant or in exceptionally fine specimens. As 

 an ore mineral, it is fourth in importance in the oxidized ores. 77 



BLAINE COUNTY 



Azurite has been found in small amounts in the Wood River region, 

 where it forms from the oxidation of tetrahedrite and other copper- 

 bearing primary minerals. In the Hamilton (Clyde) district azurite 

 has been found in the Copper Bluff mine l}4 miles from the mouth 

 of Basinger Canyon northeast of Clyde as thin blue crusts and 

 stains with malachite along bedding planes in massive blue dolo- 

 mite. 78 



n D. C. Livingston and F. B. Laney. Idaho Bur. Mines and Gcol. Bull. 1, p. 67, 1920. 

 78 J. B. Umpleby. U. S. Geol. Survey, Prof. Paper 97, p. 113, 1917. 



