WOLFRAM. 



Dull — shining. Streak bluish-green and 



shining. Adheres slightly to the tongue. 



Verv fragile. Fracture sub-conchoidal. H. 



2 to' 2-5. S.G. 2-213 to 2-303. 



Camp. Impure hydrated silicate of chrome, 



containing from 18 to 3-1 per cent, of chrome 



oxide. 



Analysis, by Ivanow :. 



Silica 36-84 



Oxide of chrome . . . 18-8o 

 Peroxide of iron . . . IrSo 

 Alumina .... 3-50 

 Peroxide of manganese . trace 

 Lime ..... 1'39 

 Water 22 46 



100-89 



Gelatinises in hot concentrated muriatic 

 acid. 



Locality. Okhansk, in Siberia. 



Name. In honour of the Russian Prince 

 Wolchonsky. 



Brit. Mus., Case 39. . 



Wolfram, Werner, Allan, Dana, Nicol, 

 Hausmann, Haidinger, v. Kohell, Naumann. 

 Rhombic : primary form a right rhombic 

 prism. Occurs massive and crystallized. 

 Colour dark greyish- or brownish-black. 

 Opaque. Lustre brilliant ; often metallic. 

 Streak dark reddish-brown. Sometimes 

 feebly magnetic. Brittle. Structure la- 

 mellar. Fracture uneven. H. 5 to b-o. 

 S.G. 7-1 to 7 6. 



Fig. 463. Fig. 464. Fig. 465. 



Comp. Tungstate of iron-protoxide, or 



WFe, with a greater or less proportion re- 

 placed by tungstate of manganese-protoxide. 

 Analysis, from Godolphin's Ball, by 

 Kerndt : 



Tungstic acid . . . 75-92 

 Protoxide of iron . .19-35 



Protoxide of manganese . 4-73 



100-00 

 BB on charcoal fuses to an iron-black 

 magnetic globule, exhibiting externally an 

 aggregation of laminar crystals. With car- 

 bonate of soda, is reduced to tungstide of 

 iron, easily separated by levigation. With 

 borax, dissolves with tolerable facility, and 

 gives the reaction of iron. 



WOLFRAM. 409 



Is decomposed by strong aqua-regia more 

 quickly than by muriatic acid ; the small 

 quantity of tungstic acid dissolved in the 

 liquid is precipitated together v/ith iron, on 

 the addition of water. 



Localities. — English. Cornwall : Huel 

 Fanny, (Jigs. 464, 465), Poldice, Stenna 

 Gwvnn near St. Austell, Godolphin's Ball, 

 Drake Walls Mine, Kit Hill, Huel Maudlin 

 in pseudomorphs after Scheelite. Cumber- 

 land ; Brandygill, Carrock Fells, Lockfells. 

 — Scotch. Island of Rona, in granite. — 

 Foreign. Altenberg, Geyer, and Ehrenfrie- 

 dersdorf, in Saxony, with tin-ore ; also at 

 Schlackenwald and Zinnwald, in Bohemia, 

 and in France. The Harz. Lane's Mine, 

 Connecticut, U. S., in Quartz. Nertchinsk, 

 in the Ural. Ceylon. 



A variety of Wolfram with a composition 



represented by the formula Fe W + 4Mn W 

 is said to occur about a mile and a half from 

 St. Francis River, St. Francis co., Missouri,'' 

 associated with Quartz and Mica. S.G. 6-67. 



Name. From wolfrig (eating^, because the 

 presence of the mineral diminishes the per- 

 centage of tin in smelting. 



Brit, Mus., Case 38. 



3L P. G. Principal Floor, Wall -cases 9 

 (British) ; 20 (Foreign). 



Crystals of Wolfi-am are extremely rare 

 in England, but are common in Bohemia 

 and Saxony. 



Wolfram is distinguished by its reddish- 

 brown streak from Tinstone, which gives a 

 grey streak. It is confined to primitive 

 rocks, and is frequently associated with the 

 tin-ores of Cornwall, Saxony, and other 

 countries; sometimes it occurs in such abun- 

 dance as to render the dressing of the tin- 

 ore difhcult, in consequence of the little 

 difference in the specific gravity of the two 

 ores. The separation of the Wolfram is, 

 however, now easily effected by the process 

 discovered by Mr. Oxland, which is as fol- 

 lows : " After crushing or otherwise pound- 

 ing the mixed substances, they are roasted, 

 and, the Wolfram still remaining unaiTected, 

 after again washing, they are roasted with 

 carbonate of soda, thus decomposing the 

 Wolfram, and tungstate of soda being formed, 

 the tin-ore is then fitted for further treat- 

 ment in the smel ting-house." * {Sir H. T. 

 De la Beche.) 



The tungstate of soda formed in this pro- 

 cess is used for giving hardness to Plaster of 



* In the modificr.tion of the above process, 

 which is now generally adopted, sulphate of soda 

 and carbon are substituted for the carbonate of 

 soda. 



