IRON. 



183 



Wolframite. — Wolfram. Iron-Manganese Tungstate. 



Monoclinic. Sometimes pseudomorphous in octahedrons 

 formed by the alteration of tungstate of lime. Also massive. 

 Color dark grayish-black ; streak dark reddish-brown. 

 Lustre submetallic, shining, or dull. H. =5-5*5. G. = 

 7-1-7 -5. 



Composition. (Fe,Mn) 4 W. A typical variety affords 

 tungsten trioxide 76*47, iron protoxide 9*49, manganese 

 protoxide 14*04 = 100. A manganese wolframite has been 

 named Hiibnerite. B.B. fuses easily to a magnetic globule ; 

 with aqua regia dissolved with the separation of yellow 

 tungsten trioxide. 



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 Camdage 

 Farm, near Blue Hill Bay, Me. ; near Mine la Motte, Mis- 

 souri ; in the gold regions of North Carolina ; in Mammoth 

 Mining district, Nevada Hiibnerite. 



Columbite. 



Trimetric. In rectangular prisms, more or less modified. 

 Also massive. Cleavage parallel to 

 the lateral faces of the prism, some- 

 what distinct.* 



Color iron-black, brownish-black ; 

 often with a characteristic iridescence 

 on a surface of fracture ; streak dark 

 brown, slightly reddish. Lustre sub- 

 metallic, shining. Opaque. Brittle. 

 H.=5-6. G. =5*4-65. 



Composition. Iron columbate, of 

 the formula F 6 Cb 2 = Columbium 

 pentoxide 79*6, iron protoxide 164, 



manganese protoxide 4'4, tin oxide 0*5, lead and copper 

 oxides 0'1 = 100. Tantalum often replaces part of the 

 columbium, and in this case the mineral is of higher speci- 

 fic gravity. B. B. alone infusible. It imparts to the borax 

 bead the yellow color of iron. 



Diff. Its dark color, submetallic lustre, and a slight iri- 

 descence, together with its breaking readily into angular 

 fragments, will generally distinguish this species from the 

 ores it resembles. 



