OF CENTRAL CANADA PART II. 99 



the base is essentially lime. All the deeply-coloured garnets are 

 strongly ferruginous ; whilst in the light-coloured varieties, iron is 

 chiefly replaced by alumina, lime or magnesia. 



Garnets occur in Canada in many crystalline strata of the Lau- 

 rentian series ; also in the less ancient crystalline beds of the Eastern 

 Townships (see Part V.) ; and in some of the trappean rocks of Lake 

 Superior. In Laurentian strata, they affect principally the beds of 

 hornblende-rock, and gneiss, which lie in contact with, or adjacent 

 to, the interstratified bands of crystalline limestone, but they occur 

 also apart from these limestones. The best-known Laurentian locali- 

 ties comprise : the banks of the River Rouge and adjacent country 

 near the " Three Mountains," in the township of Clyde, Ottawa 

 County (pink and red ferro-magnesian varieties in gneiss and quartz 

 rock) ; Seignory of St. Jerdme, on the Ottawa (red and very abun- 

 dant in gneiss) ; Rawdon Township, in Montcalm County (in quart- 

 rock) ; Townships of Chatham, Chatham Gore and Grenville in 

 Argenteuil County (red and yellowish-red varieties) ; Hunterstown, 

 in Maskinonge Qounty ; Bay St. Paul (red, in quartz-rock); Murray 

 Bay (large crystals and rounded masses in gneiss) ; Madoc Town- 

 ship (Lot 11, Con. 11, in hornblende rock with iron pyrites, &c.) ; 

 Townships of Elzevir, Barrie, &c. (dark-red, in hornblende rock) ; 

 Marmora (in quartz rock, <fec.). It occurs thus in the Laurentian 

 area generally between the Ottawa and Georgian Bay. In the 

 altered strata of the Eastern Townships, yellowish-red or pale-brown 

 garnets occur in pyroxene rock on Brompton Lake, and minute 

 grains and crystals of bright-green chrome garnet are thickly dis- 

 seminated through a calc-spar vein at the same locality. Red gar- 

 nets are found also in crystalline magnesian limestone, with talc, 

 magnetic and chrome iron ores, &c., in the Townships of Broughton 

 and Sutton ; and with black hornblende in the serpentines of Mount 

 Albert in Gaspe*. In Orford, Dr. Sterry Hunt has discovered a 

 peculiar variety of a white or light-coloured calcareo-aluminous gar- 

 net, in rounded masses of somewhat waxy aspect, mixed with ser- 

 pentine ; and he has described the occurrence of a similar variety 

 in more or less compact beds, holding specks of hative gold, in St. 

 Francis (Rep. 63 : p. 496). Finally, it may be observed, garnets of 

 a pale red-brown colour occur sparingly, with epidote, &c., in amyg- 

 daloidal traps, at Maimanse, on the east shore of Lake Superior. 



