5fi8 Professor Emerson on HalVs Geological Collections. 



90. GliANULAll LIIMESTONE. 



The contents of this parcel were manifestly scraped \\\) from the foot of a 

 limestone cliff where it was exposed to the action of the sea, and includes, beside 

 the limestone and its contents, fragments of adularia and of a very ferruginous 

 quartzite. The limestone is white, coarsely granular, and very crystalline, and 

 contains (1) coccolite, disseminated in grains .1 to 2 mm. in diameter, and rounded 

 exteriorly as if fused. The color of these grains is a deep bottle-green. They 

 are transparent to translucent; (2) quartz, with rounded fused faces ; (3) minute red 

 spinal rubies, octahedra, with rounded edges ; (4,) phlogopite in small prisms wdth 

 rounded prism faces, and of pale plum color to bronze and dull yellow on the 

 cleavage faces. 



From White Island on the south side of Frobisher Bay, near the head of it. 



97. Coccolite. 



Large mass of fresh dark-green to blackish-green coarse coccolite. 

 From parcel labeled, " From various places up Frobisher Bay and near the 

 head of it." 



98. Coccolite. 



A finer-grained somewhat weathered green coccolite. 



French Head, Field B.iy. 



The resemblance of the series of rocks here described to the Laurentian of 



Canada and the Adirondacks and to the Montalban of New Hampshire and 



Massachusetts is very marked. The typical Labradorian rocks are absent. The 



dark-red massive quartzites agree well with the Canadian quartzites of Huron- 



ian age. 



ERUPTIVE ROCKS. 



99. QUARTZDIORITE. 



A grayish-black, compact, trap-like rock, seemingly quite fresh, but effer- 

 vescing with acids. In powder blackish, with shade of green. The rock is almost 

 aphanitic with glimmering luster ; with a lens the feldspar crystals can be seen 

 as extremely fine lines. In sections plagioclase in interlaced crystals, mostly 

 elongated, is seen to make up the mass of the rock, in the interstices between 

 wliidi the other constituents appear. The feldspar is opaque — white by reflected, 

 pale brown Ijy transmitted, light, being filled with a pale yellowish-brown dust, 

 which is sometimes spread over the whole surface of the section. More often, 

 Ii(jw('\er, there is upon this as a back ground a system of darker brown lines, 

 ])arallel to the greatest length of the crystal, formed by an accumulation of the 

 same material along the lines of boundary between the separate laminai of which 

 the crystal is composed (parallel to c/) O co), and to this is superadded in many 



