182 THE CANADIAN NATURALIST. [May 



granite consists mainly of red ortlioclase, with a comparatively 

 small quantity of quartz, with which a still smaller quantity of 

 greenish mica is associated. The specific gravity of the granitic 

 gneiss is 2-G76, and that of the coarse-grained rock of the veins 

 2-594. On the north-east shore of the Bay, close to the landing 

 place of the Begley Mine, rocks are observed consisting principally 

 of granitic gneiss, in hand specimens of which, no parallel structure 

 can be detected. At some places, however, in larger masses, a 

 schistose appearance is observable, with a strike of N. 75 Q E. This 

 rock, which is syenitic, contains masses and contorted fragments 

 of gneiss very rich in hornblende. Both the fragments and 

 enclosing rock are intersected by veins of large-grained granite, 

 containing little or no hornblende or mica. In the most south- 

 easterly corner of Bachewahnung Bay, rocks occur, which, although 

 they are totally devoid of any approach to gneissic structure, 

 and possess a very different composition, bear some resemblance in 

 the manner of their association to those just described. A dark- 

 coloured, small-grained mixture of felspar and greenish-black 

 mica, with occasional crystals of reddish orthoclase, and, more 

 rarely, of greenish-white oligoclase, is enclosed in and intersected 

 by another rock consisting of a coarsely granular mixture of 

 orthoclase and soft dark-green mica, enclosing crystal of orthoclase 

 (but no oligoclase) from one-quarter to three-quarters of an inch 

 in diameter. Both of the rocks might be called micaceous 

 syenites, but as they possess a pdelorphyritic structure, they 

 probably belong to the rock species called minette. The matrix 

 of the first-mentioned and darkest coloured rock is fusible, 

 but the orthoclase which it encloses is less readily so. In both 

 rocks, where exposed to the action of the waters of the Bay, the 

 micaceous constituent has been worn away, and the grains and 

 crystals of orthoclase project from the mass of the rock The 

 specific gravity of the small-grained rock is 2-85, and that of the 

 coarse-grained enclosing rock 2-65. They are both intersected by 

 narrow veins of granite, consisting of felspar and quartz only, the 

 specific gravity of which is 2.62. At Goulais Falls, about fifty 

 miles up the Goulais River, gneiss occurs, which is very distinctly 

 schistose, contains a considerable quantity— about one-third— of 

 brownish black mica, interlaminatcd with quartzo-felspathic 

 layers, in which a transparent triclinic felspar is observable. The 

 gneiss possesses a specific gravity of 2-74 to 2-76. Its strike and 

 dip are variable ; the former seems, however, to average N. 55° E., . 



