ii7 



the southeast shore of Porcupine lake is made up largely of 

 fibrous serpentine, together with residual iron oxides 

 which in arrangement suggest original crystals like olivine. 

 The remainder of the rock is dolomite. A chemical test 

 showed the absence of chromium oxide in this rock. 



A spotted rock, from the northeast part of the West 

 Dome in lot 5 in the first concession of Tisdale, is probably 

 an altered amygdaloidal lava. The schistose matrix con- 

 sists of secondary material, dolomite, sericite, etc., and the 

 amygdules, whose margins are stained with limonite, are 

 filled with calcite, sericite, and quartz. Some of the 

 amvgdules are an inch in length. 



Ellipsoidal, Keewatin, greenstone, Night Hawk lake. 



An amygdaloidal rock from the 100-foot level of the 

 Vipond mine is entirely decomposed. The amygdules are 

 now stained with red iron oxide and show much clear cal- 

 cite. Rims of chlorite surround the amygdules, along 

 which are scattered grains of magnetite. There are also 

 some minute grains of a secondary mineral, quartz or feld- 

 spar. 



A sample from the main shaft at the Dome Extension is 

 quite schistose in thin section. Rods of plaeioclase can 

 still be recognized, while the ferro-magnesian mineral is 

 entirely altered to chlorite. Quartz is present in small 



