SOME COLORADO TUNGSTEN ORES 



95 



the gangue between the crystals. The hubnerite-wolframite specimen 

 showed a structure composed of black, bladed, acicular crystals, and, as 

 shown by the analysis, was a mixture of almost pure hubnerite and 

 woframite. 



The Black Hills specimen was a wolframite, was black and of a 

 coarsely granular structure. It contained some calcium carbonate. 



Below is given a series of tables showing the analyses of the various 

 specimens. 



No. i. Ferberite. Clyde Mine, Nederland, Colorado. 



W0 3 . 

 SiO a . . 

 FeO.. 

 CaO.. 

 MnO. 

 A1,0 3 . 

 MgO. 



Per cent. 

 6l. 



No. 2. Ferberite. Barker Ranch, Nederland, Colorado. 



Per cent. 



W0 3 .. 

 SiO a . . 



FeO.. 



Fe a 3 . 



CaO.. 



MgO.. 



MnO. 



ALO,. 



45 

 44 

 11 



35 

 50 

 37 

 10 



29 



No. 3. Ferberite. Conger Mine, Nederland, Colorado. 



WO,. 

 Si0 2 .. 

 FeO.. 

 CaO.. 

 MnO. 

 A1,0 3 . 

 MgO. 



Per cent. 



