PRE-CAMBRIAN COPPER-BEARING VOLCANICS 503 



ville to the northwest corner of the township, and in Stoke they present two 

 parallel ranges included in a breadth of about 5 miles. 



In this range of hills the strata consist chiefly of chloritic rocks in harder 

 and softer bands, the softer and more schistose constituting chlorite slates, 

 while the harder may be termed chloritic sandstones. With these are as- 

 sociated micaceous and nacreous slates often presenting a very quartzose 

 character, and thin layers of agalmatolite of a somewhat fibrous texture are 

 sometimes met with. Some of the micaceous and nacreous slates are very 

 fine grained, and on the south side of the range afford excellent whetstones and 

 hones. Many of the whetstone beds appear to be micaceous slates passing into 

 argillite. Some bands of the slate are studded with chloritoid, and in Sher- 

 brooke they enclose a bed of blood-red Jasper, passing into a siliceous, red 

 hematite, and another of a somewhat siliceous conglomerate. 



In the same neighborhood the nacreous slates are marked by the occurrence 

 of copper pyrites, containing a little gold and silver, in a gangue of white 

 quartz running with the stratification. The chloritic slates are often marked 

 by iron and copper pyrites ; and on Haskell hill on the eighth lot of the eighth 

 range of Ascot, a band of slate five feet wide, holds such a quantity of copper 

 ore as to give promise of a profitable mine. 



Selwyn suggested that slates might be volcanic as well as sedimentary, 

 but subsequent reports added nothing to the lithologic description of these 

 rocks. 



The rocks of these belts consist of two parts, one of which is stratified 

 and the other unstratified. The latter is a volcanic rock, finely crystal- 

 line and of both acid and basic phases. Quartz porphyry and andesite 

 or diabase would originally have been the extreme types. Some of basic 

 phases are altered to serpentine and all have been highly metamorphosed. 

 It is only by very detailed field study, together with microscopic exami- 

 nation, that the volcanic character of some of these rocks has been 

 ascertained. 



Associated with these are stratified rocks of similar material, but which 

 have an original clastic structure. Part contains bands of nearly pure 

 chlorite, abundant quartz veins, and much iron ore. These are thought 

 to be stratified tuffs, while other rocks, generally more siliceous, as chlo- 

 ritic sandstones and graywackes, are probably true sediments. 



Although highly altered, the volcanics of this series show their original 

 characters in localities in which the deformation has been least. The 

 acid phase of the rock is largely a quartz porphyry. A specimen from 

 the hanging wall of the Silver Star mine at Suffield is light gray in color, 

 and on the weathered surface the quartz phenocrysts are quite conspic- 

 uous. Owing to the bleaching of the base, the rock has commonly been 

 mistaken for quartzite or a species of sandstone. The following is an 

 analysis by Mr M. F. Connor, of the Geological Survey of Canada, of a 



