IRON ORES. 245 



streak dark reddish brown. Luster submelallic, shining, or 

 dull. H=5— 55. Gr=7-1— 7-9. 



Composition : lungstic acid 75*89, protoxyd of iron 19*24, 

 protoxyd of manganese 4*97. Fuses with difficulty. Gives 

 a green bead with borax, and a deep red giobule with salt of 

 phosphorus. 



Found often with tin ores. Occurs in Cornwall, and at 

 Zinnwald and elsewhere in Europe. In the United States 

 it is found at Monroe and Trumbull, Conn. ; on Camdag 

 farm near Blue Hill, Me. ; near Mine la Motte, Missouri 

 in the gold regions of North Carolina. 



SILICATES OF IRON. 



There are several compounds of silica andoxyd of iron, none of which 

 are of special interest in an economical point of view. 



Hedenbergite is a variety of augite, consisting essentially of these in- 

 gredients, (see page 151.) 



Iron chrysolite differs from ordinary chrysolite in containing oxyd of 

 iron in place of magnesia. 



Isopyre is a black glassy amorphous mineral, found in granite. H= 

 6—6-5. Gr=29— 3. Consists of silica 47* 1, alumina 13 9,peroxyd of 

 iron 20*1, lime 154, oxyd of copper 1*9. 



fyevrile, (called also yenite and ilvaite.) Occurs in rhombic prisms, 

 often with the sides much striated or fluted ; color black or brownish 

 black. Luster submetallic. Streak black, greenish or brownish. H= 

 55 — 6. Gr=38 — 41. Contains about 50 to 55 per cent, of oxyd of 

 iron with 14 of lime and 29 of silca. Fuses to a black globule. From 

 the island of Elba in large crystallizations ; also from Norway, Siberia, 

 Silesia. At Cumberland, Rhode Island, yenite occurs in slender black 

 or brownish-black crystals, in quartz. 



The following are hydrous species, giving off water when heated in 

 a tube before the blowpipe. 



Nontronite and pmguite, are earthy almost like clay, of a yellowish 

 or greenish color. 



Chloropal is a harder species, (H=3 — 4,) of a greenish-yellow or 

 pistachio-green color. Grengesite, thuringiie, knebelite, and kirwan- 

 ite, are other allied species. 



Green earth. Includes different compounds of a green earthy ap- 

 pearance. The green earth occupying cavities in amygdaloid is near 

 chlorite. It is a silicate of the peroxyd of iron with some potash, mag- 

 nesia and water ; often with other ingredients. The green grains of 

 the green sand of New Jersey, consist of silica 515, alumina 64, pro- 

 toxyd of iron 24'3, potash 996, water 77. 



Hisingerite, crons'edtite, anthosiderite, pnlyhydrite, sideroschisolite 

 chamoisite, stilpnomclane, and xylite, are names of dark brown o| 

 black species. 



Of what does wolfram consist ? With what ores is it usually associ 

 ated 7 What is said of the compounds of oxyd of iron with silica ? 



