HOFFMAN ON THE MINERALOGY OF NEVADA. 733 



BiotUe. lu fiue crystals at Silver Peak; also in the caiioa about ten 

 miles west of Palmetto. 



Borax. In moderately sized crystals in the desert south of San An- 

 tonio ; Death Valley. 



Bornite. Sparingly in Galena and Eailroad Districts. 



Borono-calcite. Hot Springs. (Loew.) 



Bournontite. Accompanies silver-ores at Lone Mountain. 



Bromid of silver. See Bromyrite. 



Calcite. In simple and modified rhombohedra, four inches in length, at 

 Bull Eun. Smaller crystals, occasionally scaleuohedra, at Eeese Eiver. 

 At Morey acute rhombohedra occur of various shades of pink, often 

 rose-colored, where they are frequently associated with rhodocrosite. 

 Two analyses show great variation of composition, although they did 

 not exhibit any perceptible difference in measurement or coloration. 

 No. 1 was taken from the extreme northeastern portion of the mine, 

 and No. 2 about twenty yards southwest of that locality. 



No, 1. No. 2. 



Carbonic acid 53.74 52.36 



Manganous oxide 3.87 4.97 



Ferrous oxide trace 0. 21 



Lime 42.28 41.42 



Silicic acid...' — 0.97 



Loss 0.11 0.07 



100. 00 100. 00 



These samples contain a large quantity of carbonate of manganese, 

 but the calcite, wherever it appears in the region between Morey and 

 Austin, contains more or less, frequently so much so as to present 

 the characteristic tints; these, however, may to some extent be due 

 to the presence of iron. 



One mile south of Mineral Hill, in a cave, occur the following 

 varieties : — 



a. Earely, small flat rhombohedra, with the lateral angles removed, 

 known as nail-head spar: 



]}. Small scalene dodecahedra ; 



c. Fine aggregations of acute rhombohedra; and 



d. Drusic and acicular incrustations and clusters, assuming great 

 varieties of form. 



Some of the acicular crystals measured nearly three-fourths of an 

 inch in length, and occurred radiating from various places from the 

 roof of the cave. 



Carbonate of copper. Bee Malachite. 



Garhonate of iron. See Siderite. 



Carbonate of lead. See Cerussite. 



Carbonate of lime. See Calcite. 



Carbonate of manganese. See Rhodocrosite. 



