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BULLETIN 131, UNITED STATES NATIONAL MUSEUM 



luster than azurite. This showy rosette attracted attention to the 

 specimen and the mineral was found, by chemical tests, to be linarite. 

 This led to a more detailed examination of other specimens of sup- 

 posed azurite from this mine and one other specimen was found to 

 be linarite. This consists of massive cerusite colored dark by 

 included unoxidized galena and encrusted by linarite, limonite, lead- 

 hillite, and a little caledonite. The linarite is implanted both upon 

 the cerusite and the limonite in the form of minute blue flat prismatic 

 crystals. Examined under the microscope these are seen to be 

 elongated on the & axis and flattened, probably parallel to the basal 

 pinacoid giving parallel extinction between crossed nicols which 

 suggests orthorhombic symmetry. They are transparent bright 

 blue by transmitted light and are nonpleochroic. While the crystals 

 are not very satisfactory for measurement one was measured and 

 found to have the habit shown in Figure 160. It gave the following 

 angles : 



Measurements of linarite from the Caledonia mine, Wardner 



It is probable that linarite was of fairly frequent occurrence in this 

 mine, but it was confused with azurite while the oxidized ores were 

 being worked. 



Some small crusts of linarite have been seen on specimens from the 

 Sierra Nevada mine in Deadwood Gulch. 



Linarite occurs as a fine blue crust of indistinct columnar crystals 

 associated with a little caledonite and leadhillite and some cerusite 

 surrounding a lump of granular galena containing some chalcopyrite 

 from the Lookout Mountain mine on Pine Creek. 



A fine large crystal of linarite has been seen in a cavity in a mass of 

 cerusite said to have come from the Hercules mine. 



