II. 



passed over a Wilfly table, which gave three products, 

 concentrates, middlings, and tails. The middlings from 

 all three tables were treated on a fourth table which pro- 

 duced concentrates and tails. The concentrates after 

 draining were ready for shipment. 



The ore was graded, and sold according as the content 

 of chromic oxide was greater or less than 50 per cent. The 

 highest percentage reached was very rarely above 55, and 

 with some ores difficulty was experienced in obtaining even 

 50 per cent. This last trouble was evidently due to the 



Photomicrograph of chromite ore showing intergrowth of two varieties, — black, 

 opague iron and chromium-rich variety, showing black; and brown, translu- 

 cent, magnesian variety, showing mottled. The white streaks are glare from 

 films of inclosed serpentine. X 55. 



chromite having an undue amount of Cr 2 O3 replaced by 

 Al 2 O 3, so much so that the per centage of Cr 2 O 3 remain- 

 ed low even with a very complete removal of the gangue. 

 Thin sections of some of the ore show it to be composed 

 of an opaque black variety, high in Cr? O3, and a red- 

 dish, translucent variety containing less Cr 2 O3. 



35064— 8| 



