180 



MINERALS AND GEOLOGY 



Jerome, Escott, Lansdowne, Burgess, Madoc, Marmora, Galway, ant 

 indeed throughout the Laurentian region generally, lying between the 

 Ottawa and Georgian Bay. In Laurentian strata, likewise, on the- 

 River Rouge, east of the Ottawa, and at Stony Lake, in the Township 

 of Dummer or Burleigh, as well as in Bathurst and Burgess, granitic 

 veins containing albite or soda-feldspar replacing or accompanying 

 orthoclase, have long been known. The opalescent variety of Albite 

 known as Peristerite (see Part II., No. 58) coems from a vein of this 

 kind in Bathurst. Other veins and some considerable masses of 

 granite occur on the north and north-east shores of Lake Superior, 

 as in the vicinity of Michipicoten, at Point-aux-Mines, and here and 

 there about Bachewahnung Bay, and elsewhere. A mass of red 

 granite, inferred by Sir William Logan to be of Huronian age, is 

 described as having broken through and tilted up Laurentian gneissoid 

 stnta south of Lake Pakowagaming on the north shore of Lake 

 Huron; and granitic dykes and veins occur in the Bruce Mines- 

 District. A flesh-red granite underlies beds of Trenton limestone in 

 the Township of Storrington, north of Kingston. Finally, intrusive 

 masses and dykes of white or light-coloured granite occur on Lake 

 Memphremagog in the Township of Stanstead, and others in the 

 Townships of Hereford, Barnston, and Burford, of that district. 

 Similar masses have been noticed on Lake St. Francis, Lake Megantic,. 

 and in the intervening townships. Some of these granitic masses, as 

 described in the Revised Report of the Geological Survey (1863), 

 cover areas of from six to twelve square miles. 



A granite which contains hornblende in place of mica, was formerly 

 defined by most geologists as /Syenite, but this term is now generally 

 restricted to a granitic greenstone, or mixture of orthoclase and horn- 

 blende. Keeping to the latter definition, we have in syenite a more 

 or less distinctly granular or granite-like aggregate of potash-feldspar, 

 and hornblende : the feldspar being usually red or white, and the 

 hornblende green or black. Quartz in small amounts ia also occa- 

 sionally present. As in ordinary granite, both coarse and fine-grained 

 varieties of syenite occur. In the latter, the component minerals 

 are blended into a more or less uniform dark-green mass, and the- 

 rock resembles, and can rarely be distinguished from, an ordinary 

 greenstone. From this trappean rock into well-defined syenite, indeed,, 

 an evident transition may be occasionally traced. On the other- 



