THE MINING AND QUARRY INDUSTRY 



99 



rock adjacent to the ore is much more acid and contains practically 

 no dark silicates. The magnetite is gathered into layers or bands 

 or is distributed as small grains through the rock mass. When the 

 bands coalesce, they may form a body of high grade ore several 

 feet thick. Such rich zones were sought for and exploited in 

 preference to mining the whole breast of the deposit, so that there 

 is little system in the way in which the workings have been laid out. 



The principal openings in order from south to north, are known 

 as the Elliot, White Flint, Big pit, Summit, Lundrigan and Little 

 pit. With the exception of the Elliot, which seems to lie at a lower 

 horizon, the shifts are all in the same zone. The total length meas- 

 ured along the outcrop is over 2000 feet. There are also extensive 

 surface workings. The last mining was done in the Elliot slope 

 which is bottomed at 500 feet. It is said that the ore shows a 

 thickness of 9 feet in the lowest level. At the White Flint the 

 outcrop is about 20 feet from wall to wall and the greatest depth 

 reached 1200 feet. The Big pit is separated from the White Flint 

 by a diabase dike which extends north over the summit of the hill. 

 Another dike follows the line of outcrop, cutting vertically across 

 the ore body. The Big pit reaches a depth of 2200 feet on the dip. 

 which begins at 50 and gradually lessens until nearly horizontal. 



The principal gangue minerals accompanying the magnetite are 

 quartz and feldspar. According to former practice the material 

 was roasted, crushed by stamps and separated in a crude form of 

 jig. The object of roasting was simply to render the ore friable 

 so as to diminish the labor required for crushing. There is little 

 sulfur present. The composition of the ore is shown by the follow- 

 ing analyses kindly furnished by Mr W. Carey Taylor : 







1 



2 



3 



Ferric oxid (Fe 2 ( ).,).. 



46 



•152 



49-757 



67.274 



Ferrous oxid (FeO).. 



20 



•735 



22.354 



30.224 



Silica (Si0 2 ) 



3 1 



.70 



26 . 1 34 



3.000 



Sulfur (S) 





.008 



.016 



.08 



Phosphoric acid 











(P 2 O s ) 





.005 



.016 



.165 



Alumina (A1X)..,) .... 



1 



.076 



1 -531 





Manganous oxid 











(MnO) 





037 

 364 

 872 



.090 



•315 

 .229 





Lime (CaO) 







Magnesia (MgO)... 







100.949 100.442 100.743 



