. Annual report . sts now essentially of two minerals, hornblende and plagio- 1913 Cobalt=Nickel Arsenides and Silver 55 clase, while quartz, leucoxene, chlorite, pyroxene, saussurite and other minerals aresubordinate in amount. In a few cases it can be clearly seen thai the hornblende issecondary after pyroxene. Quartz occurs sometimes in beautiful micrographlc inter-growths with feldspar. Thin sections from the Argentite (the southeast corner of the northeast quarterof the south half, lot eight, in the fifth concession of Coleman township), were exam-ined by M. B. Baker in the laboratory of
. Annual report . sts now essentially of two minerals, hornblende and plagio- 1913 Cobalt=Nickel Arsenides and Silver 55 clase, while quartz, leucoxene, chlorite, pyroxene, saussurite and other minerals aresubordinate in amount. In a few cases it can be clearly seen thai the hornblende issecondary after pyroxene. Quartz occurs sometimes in beautiful micrographlc inter-growths with feldspar. Thin sections from the Argentite (the southeast corner of the northeast quarterof the south half, lot eight, in the fifth concession of Coleman township), were exam-ined by M. B. Baker in the laboratory of Prof. Rosenbusch, Heidelberg, Baker found the rock to consist of a fibrous, felt-like groundmass of talc, musco-vile, saussurite and plagioclase. Scattered through this matrix are hypidiomorphicto idiomorphic crystals of diallage. Mr. Baker considered the rock to be a doleriteor diabase. A chemical analysis was made of the diallage by Mr. N. L. Turner, andit was found to have the following composition:. Fig. 25. Torsion cracks in Keewatin greenstone, lot 15 in the second concession of Bucke. SiO., i1^ I , | CaO MgO Combined water (3) ACID INTRUSIVES The acid igneous rocks of the Keewatin, which are not widely distributed in theCobalt area, include felsite, feldspar-porphyry and quartz-porphyry. At the north end of Sasaginaga lake an occurrence of a white to light greyfelsite presents a striking appearance on account of its light color. It is finein grain and comparatively fresh, and consists of feldspar and quartz, the feldsparpredominating. The rock has a micro-porphyritic texture, due to the presence ofphenocrysts of feldspar and quartz. Often the feldspar rods in the matrix are arrangedin parallel lines, which curve around the phenocrysts, producing what is known as a !( Bureau of Mines No. 4 flowage texture. Colored constituents appear to be absent. Some secondary calcite ispresent, with which also occurs some secondary quartz. M
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectminesandmineralresou
