190 BULLETIN 42, UNITED STATES NATIONAL MUSEUM, 



M E R (3 U K Y . 



Meecury Minerals. 



mercury. (quicksilver.) 



Compositioii : Pure mercury. Occurs in small Quid globules scattered 

 througb a gangue. Free mercury is not common, but is found in small 

 amounts in a number of mines, and is illustrated by a single specimen 

 here. Six other specimens showing free mercury are included in the 

 ore and the New Almaden collections. 



(1) Free mercury globules, with ciunabar iu quartz. Rattlesnake Miue, Sonoma 

 County, California.. (,15936.) 



CINNABAR. 



Composition: HgS. Sulphide of mercury, containing mercury 86.2 

 per cent, and sulphur 13.8 per cent. 



It crystallizes in the rhorabohedral system, crystals being very com- 

 plex and not common ; it generally occurs granular and massive. It 

 varies in hardness from 2 to 2.5 ; its specific gravity is 8.99. It is cochi- 

 neal red in color, has aii adamantine luster, and is subtransparent to 

 opaque. Cinnabar is the universal mercury ore, and is illustrated by 

 four specimens : 



(1) Crystallized, cemeutiug a quartz conglomerate. Phcenix Mine, Pope Valley, 

 Napa County, California. (15985.) 



(2) Crystalline, botryoidal mass overlaid hy chalcedony. Phteuix Mine, Pope Val- 

 ley, Napa County, California. (65ol5.) 



(3) Massive, with layers of quartz. Pomposa Mine, Santa Barbara County, Cali- 

 fornia. (56420.) 



(4) Crystalline and massive. New Hope Mine, Fresno County, California. (Io08.}.) 



Mercury Ores. 



For the extraction of the metal mercury ores are roasted, by which 

 treatment the combination between the mercury and sulphur is broken 

 up and the mercury is set free. This roasting is carried on above the 

 boiling point of the metal, and it is therefore volatilized with the prod- 

 ucts of combustion. The products of combustion are conducted 

 through condensers, where the mercury collects and is drawn oft". 

 Mercury, on account of the fact that it is fluid at ordinary temperatures, 

 occupies a unique position among the metals. Moreover, its extensive 

 use in extracting the precious metals, for which enormous quantities 

 are used, makes it doubly interesting and valuable to the metallurgist. 



While specimens of cinnabar occur in many localities, yet the pro- 

 duction of mercury is mainly confined to three localities : Almaden in 

 Spain; California, especially New Almaden, and Idria iu Austria. 



