GEOLOGY OF MOOSE RIVER GOLD DISTRICT — WOODMAN. 69 



estimate I have been able to make elsewhere, and it is probably- 

 fair to consider it as near a maximum for any considerable 

 breadth of rock. It is perhaps exceeded by two or three cases 

 near the Isaac's Harbour district. 



It is interesting to note, also, that in a portion where slate 

 appears at first sight to be the only sediment, a large amount of 

 arenaceous material is present. lu the north trench it amounts 

 to 33%. in the second trench to about 45%, and in the quarry on 

 areas 71 and 72, where the slate is unusually abundant and clear, 

 to 15%, in cross-section. 



P.VRT III. METALLIC COxMTENTS OF THE ROCKS, 



PYRITE 



Relation to stratification 'planes. — Pyrite is the most import- 

 ant sulphide, and the most abundant. In connection with it and 

 the arsenopyrite much of the gold occurs, in large part inti- 

 mately associated. The pyrite is here chiefly in small cubes 

 and granules, rarel}'' in clusters of crystals or large granular 

 masses. In the veins, however, granular accumulations are 

 not uncommon. Reference has already been made to the pres- 

 ence of pyrite along the major planes of division of the strata. 

 This is its most characteristic attitude in slates, or between slate 

 and whin, even when much folded. These major planes of separ- 

 ation mark the greater chancres in conditions ot' sedimentation, 

 resulting in greater textural alternations ; and the contiguous 

 strata have comparatively little cohesion. Hence, with the rust- 

 ing of the pyrites, fracture is easy along them. The minor 

 planes divide strata of greater similarity and cohesion. Within 

 quartzite, or between adjacent beds of it, the distribution of the 

 mineral is irregular for the most part, and the crystals lie in all 

 attitudes. Occasionally they occupy stratification planes in the 

 whin ; but rarely, for the rock is dense and homogeneous. 



In the slate, the sulphide lies irregularly in the stratum, or 

 more often is found along minor or major planes of separation. 



Proc. & Trans. N. S. Inst. Sci., Vol. XI. Trans. F. 



