ii4 



over screens, close above which are the inlets of suction 

 fans by which any fibre is removed. The undersize passes 

 on to the next screens while the oversize is ground further. 

 Partial grading of the asbestos is effected by this removal 

 of the fibre at the various stages in the crushing process, 

 and this grading may be further improved by screening. 

 Magnets are usually employed over the shaking screens to 

 eliminate particles of iron ore. 



The milled fibre is separated into three or more grades, 

 and the crude asbestos usually into two. 



Chromite. 



The most important chromite deposits are reached 

 from Black Lake village, but as they all present similar 

 characteristics, the Montreal pit is described as a typical 

 example. 



Mode of Occurrence. — The Montreal pit is in a 

 serpentinized peridotite near a contact with diabase, — the 

 latter rock occurring in the opposite slope of the little 

 valley. The ore body consists chiefly of a series of lens- 

 shaped bodies of massive chromite. Associated with this 

 is a large quantity of ore consisting of disseminated grains 

 of chromite in the serpentine country rock, sufficiently rich 

 to concentrate. 



The whole deposit has been faulted and squeezed to 

 such a degree as to produce an infinite number of slick- 

 ensided surfaces. For this reason the ore is deceiving, 

 as it tends to break along the film of serpentine in these 

 slickensides so that what may appear to be merely a block 

 of serpentine is in reality massive ore. Cutting the serpen- 

 tine are several kaolinized granitic dykes, numerous blocks 

 from which are to be found on the dump and some of which 

 contain an unusual pink vesuvianite. 



Mining and Milling. — The ore was mined by means 

 of open cuts, and by a drift from the bottom of the main 

 or lower pit. At least 2,200 tons of crude and 500 tons of 

 concentrated ore have been shipped from these workings. 



In the method of concentration used, the ore, after 

 preliminary breaking in a jaw crusher, was fed to three 

 batteries of five stamps each. The pulp from each battery 



