USEFUL METALS 171 



Antimony : Its Properties, Occurrences and Uses 



Properties. Antimony, symbol Sb, is a tin white, cxtrvnu-ly 

 brittle metal. It is distinguished from all other metals, save I >i-- 

 muth, by its brittleness and from all the other metals in the char- 

 acter of its salts. In many respects these are more closely allied 

 to the salts of the metalloid arsenic than to those of the true 

 metals. It fuses easily before the blow pipe forming dense white 

 fumes of the white oxide, Sb 2 O 8 . If heated intermittently there 

 appears upon the button prismatic crystals of artificial valen- 

 tinite. The metal does not tarnish at the ordinary temperatures. 

 It is soluble in concentrated HC1; specific gravity, 6.7, molting 

 point, 630.5 C., and its atomic weight is 120.2. 



Ores of Antimony. Native antimony, Sb, 100 per cent. Sb. 

 Often alloyed with silver, arsenic and iron. 



Stibnite, Sb 2 S 3 , 71.4 per cent. Sb. Massive or in reticulated 

 crystals. 



Kermesite, 2Sb 2 S 3 ,Sb 2 03, 75 per cent. Sb. A cherry-red pris- 

 matic mineral. 



Valentinite, Sb 2 O 3 , 83.3 per cent. Sb. Occurring in white or- 

 thorhombic crystals. 



Senarmontite, Sb 2 O 3 , 83.3 per cent. Sb. Occurring in white iso- 

 metric crystals. 



Cervantite, Sb 2 3 ,Sb 2 O 5 , 78.9 per cent. Sb. Yellow or yellowish- 

 white in color. 



Antimony occurs also with many lead ores as galenite. From 

 this mineral the extraction of the antimony is somewhat difficult. 

 It occurs also with several silver ores. It is also associated with 

 some gold ores. 



Origin of the Ores. Native antimony is derived from the 

 reduction of the other ores of the metal. Stibnite is slightly sol- 

 uble in water at 80 C., and its recrystallization from such a 

 solution is perceptible. Stibnite has been reported from Tuscany 

 as a product of solfataric action. According to F. W. Clarke, this 

 mode of deposition is ascribed to the fact that the metal forms 

 easily volatile compounds. In most cases stibnite has been de- 

 posited from alkaline solutions which have the power to dissolve 

 silica. In this manner solutions bearing antimony may be trans- 

 ported a considerable distance from the original ore body. The 

 same alkaline solutions have the power to dissolve silica, and this 

 explains the presence of quartz as the most important gangue 

 mineral for stibnite. 



