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The bent and metamorphosed condition of the calcite shows the shearing and crushing which the rock has undergone. 11 Phyllite same location as No. 9. A dark red, finely laminated rock consisting chiefly of decomposed biotite and feldspar, occasional quartz grains and sericite and much iron oxide.
A barrier-berg bearing north-west appeared to be about 25 miles long. We pushed the ship against a small banded berg, from which Wordie secured several large lumps of biotite granite. While the 'Endurance' was being held slow ahead against the berg a loud crack was heard, and the geologist had to scramble aboard at once.
The labradorite contains inclusions of rutile and biotite and has a well-developed wedge structure and cross fracture due to the pressure and shearing which it has undergone. It is also somewhat stained by the decomposition of the magnetite. On the map of the portage route to Lake Michikamau; that lake, the Grand River and Groswater Bay are taken from the map accompanying the report of Mr.
Plagioclase, microcline and quartz are the predominating minerals, while biotite, titanite, epidote, apatite, zircon and garnet are present in smaller quantities. There is also a small amount of hematite, pyroxene and sericite. The rock, which is of a granitic composition, contains numerous crystallites and has been subjected to considerable strain and crushing, which has resulted in foliation.
The mica in recent volcanic rocks, gabbros, and diorites is usually Biotite, while that so common in metamorphic limestones is usually, if not always, Phlogopite. Amphibole is a general name for all the different varieties of Hornblende, Actinolite, Tremolite, etc., while Pyroxene includes Augite, Diallage, Malacolite, Sahlite, etc.
Biotite. This is a variety of mica in small crystals, of a dark brown color, and quite plentiful in the gneiss inclosing the veins of limestone. Up in the older quarries it is more abundant; on the north wall of the vein it is often in very fine specimens, and there even in large number, in a locality, generally a pocket in the gneiss.
5-Mica Granite Gneiss Country Rock near Caribou Ridge. In the hand specimen the rock has the same appearance as No. 4, if anything, it is somewhat more compact. The principal minerals are, plagioclase, biotite and microcline, with smaller quantities of quartz, iron oxide, pyroxene and garnet. The feldspar is decomposed with the resulting formation of epidote, which is quite prominent.
In the hand specimen it is an apparently pure orthoclase but in the thin section small scattered quartz grains are observed; as well as the alteration products, Kaolin and sericite. The minerals at contact are quartz, biotite, magnetite and hornblende. Both the quartz and orthoclase contain dust inclusions and crystallites, while the evidences of shearing and crushing are abundant.
Muscovite is often called common or potash mica; Lepidolite is characterised by containing lithia in addition; Biotite contains a large amount of magnesia and oxide of iron; whilst Phlogopite contains still more of the former substance. In rocks containing quartz, muscovite or lepidolite are most common.
Half way to the head of the lake is a dike having a total width of eight feet, consisting of a central band of segregated quartz, six feet wide, cut by numerous thin sheets of biotite, which probably mark the planes of shearing. The quartz is bordered on either side by a band of orthoclase, one foot in width.
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