('OL|,K(jri<)NS IN KOONOMU^ (JKOI.OtJV A\l> M l! P ALI-TKOV. 1^7 



\-l) licsitlimm, nMnainiii;^ in tlio oxide fmiiam's afttM- th(« rxtractiou of tlu) zinc, 

 . (iiitains iron and munjjant'so, which iiro oxtrat'toil in a hhist rnrnaco aa spiegoleiHon. 

 (.■)-lia."<.) 



(:t> Rcsidiiniii. I'loiii oxide I'lii nacos, sliowin^j crystallized oxide of zinc. (54i:W.) 



.^ru.i.i.L ruJi'XACE .sahplks. 



(l) Re.sidnuni, the residue after the extraction of tiie zinc from Franklinito ore in 

 in' zinc oxide furnace. It contains the iron ami nuiuj^aneso of the ore. (.'j4UG.'>. ) 



[0.) Coal, anthracite coal used for fuel. (54U(!«>.) 



(:i) Limestone, calcite, containing a little pyrite; used for llux. I'roni Sinj,' Sinf;, 

 Westchester County, Now York. (.')19fi7.) 



(J) Slas- (r)4<H;4.) 



(ii) Graphite, carbon, in spiegel slasj. (5490:1.) 



((')) .Spiegeleisen,an alloy of iron and niansanese, rich iu combined carbon ; used 

 in tiie manufacture of steel. (.0406"'.) 



(7) Zinc oxide, from the ga.s ways. (54969.) 



TIN. 



Tin Mineral. 



cassiterite. (tin stone, stream tin.) 



Composition: S11O2. Oxidt' of tin, containing' tin 78.67 per cent, and 

 oxygen 21.33 per cent. 



[t crystallizes in the tetragonal system, crystals being very com- 

 plex and generally tNvinned. It sometimes occurs in globular form 

 with fibrous stru(;ture, and also ma.ssive. It varies in hardness from 6 

 to 7 and in s[)ecitic gravity from (>.4 to 7.1. Its general color is brown, 

 l)ut it occurs of several .shades of red and gray, also white. Sometimes 

 it is nearlj" transparent, and graduates into opaque. 



Ca.s.siterite is the universal tin ore and can readily be distinguished 

 from niost minerals with which it could be confounded by its higii spe- 

 cilic gravity. It is represented by a single specimen here. Others will 

 be found with the tin ores. 



(1) Rough crystals. Irish Creek, Kockbridgo County, Virginia. (30866.) 



Tin Ores. 



It has been generally supposed that tin was a rare metal in this 

 country. This, however, is only partially triu', the occurrence of cas- 

 siterito, the l>inoxide of tin, in small (piantities, being known to min- 

 eralogists frtnn a large extent of territory for many years; but it is 

 oidy in very rare instane.es that tliis oe(Mirrenee has given «'ven the 

 slightest evidenw of tlu're being a deposit wiiieli would pn»ve of any 

 commercial value. The first discovery that was at all favorable was 

 made by Professor . I aekaon in New (lampshire in ISIO. Specimens of 

 this ore, together with a bar of tin produced, have bi'eii in the Museum 

 many years. 



