GEOLOGY OF MOOSE RIVER GOLD DLSTRICT — WOODMAN. 59 



The fissility of both slates and quartzites becomes more 

 marked, the cleavage laminse separating with increasing ease, 

 the slates turning a paler color, and the quartzites whitening 

 much from the grayish green so common in the unaltered con- 

 dition. Where pyrite lies in abundance along stratification 

 planes, its weathering aids in separating the strata and causing 

 the appearing of open spaces between them. 



PART U.— VEINS. 

 COMPOSITION. 



Constituents. — The gangue in the veins of Moose River is 

 chiefly quartz, with some calcite. Most of the leads have shown 

 only quartz, and the cross veins appear to have no other gangue. 

 The Little North has much calcite, and a few others have large 

 amounts erratically distributed ; but in no case does it form the 

 main part of the lead. It is mixed with the quartz without 

 apparent system, sometimes occupying the whole width of the 

 vein, again next the country rock, often in the center ; or in a 

 few instances interbanded with quartz in distinct layers. It is 

 surprising to find its cleavage planes often curved, giving a 

 resemblance to a light colored siderite. Tests, however, have 

 shown it to be calcite. The curving is gentle, but in a few 

 cases quite sharp monoclinal folds half an inch high have been 

 found. It is evident from a study of the adjacent rock that the 

 curving is a result of dynamic action subsequent to th^ forma- 

 tion of the veins. 



Arrangement of minerals. — The quartz is rarely cellular or 

 drusy. A few druses show very distinct crystal faces on the 

 walls. The cellular portions of the gangue are especially white, 

 or are rusted by decomposition of a sulphide. Normally, how- 

 ever, the gangue is dark and ribbony, and uniformly dense. 

 The gold is associated with this type, on the whole, more than 

 with the other. 



The leads never show a distinct comb structure. When 

 druses occur at all, they are in the interior of masses which are, 



