128 



westward at angles varying from 45 to nearly 90 . In 

 the case of No. 1 deposit, the ore body at its outcrop at 

 the northern end has a thickness of 105 feet (32 m.). In a 

 drill hole which intersected the body at a vertical depth of 

 410 feet (125 m.), the ore body had a thickness of 65 feet 

 (19-8 m.). As indicated by the results obtained from a 

 magnetometric survey, the ore body has a length of about 

 2,000 feet (610 m.). 



It is believed, for the following reasons, that the ore 

 bodies have formed through the partial replacement of 

 schistose quartz porphyry by iron ore, along sharply 

 defined zones. 



The prominent banding of the ore, sometimes on a coarse 

 scale, sometimes microscopic in its fineness, is, when seen 

 in thin sections under the microscope, very regular, and 

 gives the impression of being an original structure, not a 

 secondary one imparted in some way to the ore after its 

 formation. 



The parallelism of the banding of the ore (seemingly an 

 original structure) and its attendant slaty cleavage, with 

 the walls of the ore bodies and with the planes of schistosity 

 in the neighbouring rocks, forcibly suggests that the ore has 

 replaced a schistose rock, and has partly preserved the 

 original schistose structure. 



The finely granular quartz present throughout the ore, as 

 well as the less abundant granular feldspar, may readily 

 be regarded as representing original constituents of the 

 replaced, schistose rock, possibly sheared quartz porphyry. 

 That the original rock was schistose is supported by the fact 

 that in all cases where observations were possible the 

 country rock, as it neared the ore bodies, was found to be 

 progressively more schistose. 



Under the above hypothesis, the occasional narrow bands 

 of dark green schist seen in No. 1 body may represent a 

 rock variety that more strongly resisted the replacing 

 action of the ore bearing solutions. The apparently basic 

 composition of these bands, and the occurrence of schistose 

 diabase along the western walls of the ore body, suggest 

 that they may represent dykes of diabase. 



As regards the quartz veins, in the case of a thin section 

 of ore charged with small reticulated and crenulated quartz 

 veins, it was seen that the alternating microscopically 

 fine lines and extremely narrow bands of quartz, quartz 

 impregnated with iron ore, and nearly pure iron ore, 



