COLLECTIONS IN KCONOMl* ' (;r.()l-< >(;V AM) MKTALIJKGV. 20l 



SU L r II I i:. 



SlLI'inU MiNKRALS. 



suLPiii i;. 



Composition: S. I'liiv siilpliiir, trcqnnitlN roiitaiiiiii^' r\ny aiitl car- 

 boaaceoiis iiiattrrs. 



It ciystalli/.i's ill tlu' oitlioilioiiibic system, sliowiiij^ especially a lai<,'e 

 variety of oetalu'dial planes, crystals often complex and lre«piently 

 twinned. It also occurs massive and in layers. It varies in hardness 

 from 1.5 to 2.5 and the si»ecitic {^^ravity is '^.0.2. It has a (characteristic 

 yellow color, but is sometimes reddish or «j:reenisii. It is trans|iarent 

 to translucent, and is sectile. 



It is found in all volcanic rej^ions, but especially on the Islaml ot 

 Sicily. Larjje deposits of it are known in Utah and Nevada. A siufj^le 

 specimen is shown : 



(1) (.'ryntals on niassivc. Rabbit lliile Mini-, lluiiilxtlilt ('tmntv, N'evadji. 



(ir.i.-K-,./ 



The sulphide of iron, pyrite, and the sulphide of zinc, Ideiide, the 

 sulphur of which is sometimes utilized for the manufacture of sulphuric 

 acid, have beeu described under iron and ziuc minerals. 



Sulphur Ores. 



Sulphur is found in nature, free, combined directly with various met- 

 als, ami in oxidized compounds, of these the latter can not he used as a 

 source of sulphur. Of the sulphides, only the bisulphide of iron, pyrite, 

 and the sulphide of zinc, blende, have been utilize<l for their sulphur, 

 and the latter only in connection with roastinj,' the blende to remove 

 the sulphur previous to smeltin<; for zinc. Practically the only sources 

 of sulphur are free sulphur and iron i)yrite. 



Free sulphur is found in all volcanic re<^ions, bur a very iar^e jmh tion 

 of the world's supply is drawn from the Island of Sicily. It is found 

 in large amounts in our Western country, but too far from transporta- 

 tion to be utilized. Iron pyrite is a very common mineral, but large de- 

 jiosits fre*^ enough from arsenic, to be used, are not common. Two or 

 three mines, however, in this country produce large anu)unts of pyrite 

 which are used for acid-maUing. When, as is cpiite fre(puMit, pyrite 

 contains a small amount of copper, the sulphur is sometinu's utilized, 

 and tiien the copper is extracted. 



Almost the sole use of sulphur is for the manufa<tm'e of sulphuric 

 acid. For this purpose the sulphur is burned to sulphurous acuI 

 (SOi) on a grate, and then <'ondu<Med witli a slight excess of air into 

 large lead chambers and mixed with steam and nitrous fumes, where 

 the sulphurous acid (SOj) is oxidized to sulphuric ardiydride (SO3) 



