242 THE CANADIAN NATURALIST. [Jan. 



on the south shore. These rocks have been generally described 

 in the Geology of Canada as sandstones, conglomerates, stratified 

 traps and amygdaloids. In referring to them more minutely, the 

 following rock-varieties may be distinguished as belonging to the 

 upper group of the series : — 



Granular Melaphyre, — A large number of the rocks of this 

 series which have hitherto been described as traps and greenstones, 

 belong to this species. The simplest variety of it is seen at the 

 north-west end of Michipicoten Island, and consists of two 

 minerals only, a felspar and a greenish black mineral. The 

 felspar is the principal constituent, possesses a red, almost pink, 

 colour, which it loses on ignition, and being readily fusible and 

 but slightly decomposed by acids, is most probably oligoclase, or 

 closely allied to that species in composition. The dark coloured 

 mineral is easily fusible and has the appearance of augite. Some 

 of it appears soft and decomposed, and has most probably been 

 converted into delessite. These two minerals are combined into a 

 small grained, distinctly compound rock, which does not effervesce 

 with acids, and whose red colour is visible at a considerable 

 distance. It is very seldom however that this rock is observed 

 with such a bright colour, or with constituents so distinctly 

 separated. Much more frequently the felspar has a dark reddish- 

 brown colour, and the grains of augite or delessite have a very 

 indistinct contour. This is the case with some of the melaphyres 

 of Mamainse and Gros Cap. When the brown coloured felspar 

 predominates, and the augitic or chloritic constituent becomes 

 scarcer and even more indistinct, rock-varieties are developed 

 belonging to the species Porphyrite, hereafter to be described. 

 When, on the other hand, the dark greenish constituent gains the 

 upper hand, and is recognisable as consisting almost exclusively 

 of delessite, it gives rise to the variety of melaphyre next 

 described. 



Delessitic Mela pi tyre. — This rock has a greenish-gray colour 

 and consists of a granular mixture of felspar and delessite, with 

 small portions of magnetite and undecomposed augite. In some 

 instances mica is also found as a constituent. The delessite, 

 besides occurring in small grains, often forms larger rounded 

 particles and amygdules, without however imparting to the rock 

 a very marked amygdaloidal structure. The rocks enclosing the 

 cupriferous beds of the Pewabic and Quincy Mines, and that from 

 the Quincy adit are examples of this variety, and have already been 



