84

The main occurrence of peridotite is in the cliff immediately west of
the contact. It has been opened at a point 45 feet above where the contact
was exposed and 100 feet southwest of it. There the masses lie in a zone
that is 2 feet wide and trends north 29 degrees west and can be-followed to
the top of the cliff 75 feet above and 300 feet to the north.

The basalts appear to have come up for the most part quietly as flows
of molten rock, with little or no accompanying explosive action. In their
passage upward they have picked up and carried to the surface masses of
peridotite and quartz diorite. As the lava was extruded its internal
pressure was suddenly diminished through the escape of contained gases
and there was a gradual loss of heat. It is probable that the diminished
internal pressure caused the load of foreign material, peridotite and quartz
diorite, to sink to the bottom of the molten layers and to remain near the
point of extrusion while the main basaltic flow solidified farther on. This
may account for nearly all the larger peridotite masses being in the cliff
near the contact mentioned above. _

COMMERCIAL POSSIBILITIES.

A few, small prospect holes have been opened on top and on the sides
of the dyke-like cliff. A large percentage of the masses does not contain
peridot of the proper size or colour for commercial purposes, and a fairly
high proportion of waste must be looked for in mining. Further develop-
ment work should be done in the face of this cliff and possibly later by
sinking along the granite contact. Most of the waste rock will have to
be eliminated at the mine, so as to save freight charges. Since there is no
market for uncut stones in Canada nor in the United States, arrangements
will have to be made for cutting the stones before their exploitation can
be commercially successful.

MUSCOVITE.!

Mica is marketed in sheet, splittings, and ground form. The non-
inflammable and. non-conducting properties of sheet mica render it par-
ticularly suitable for the electrical industry and in place of glass in furnaces,
stoves, and so forth. It takes the place of glass in windows subjected to
shock and vibration, such as shields in aeroplanes, and windows in the
conning towers of warships. Ground mica is used for lubrication, for
annealing steel, as a filler in various compounds, in paints, wall-papers,
and for other purposes. Sheets for condensors should yield a rectangle
at least 13 by 2 inches in diameter. Prices per pound vary according to
size of sheets, colour, and freedom from stains. It is estimated that the
percentage of marketable sheet mica produced by Canadian mines averages
above 5 per cent of the run of mine and rarely exceeds 10 per cent. In
1917 split and trimmed Canadian amber mica (phlogopite) sold in
the United States at prices ranging from 11 cents per pound for 1 by 1-ineh
sheets, $1 per pound for 3 by 3-inch sheets, $3 per pound for 6 by 6-inch
sheets, to $5.50 per pound for 8 by 10-inch sheets. White mica, from the

ide Schmid, Hugh S., ‘‘Mica, its occurrence, exploitation, and uses.’’ Mines Branch, Department of Mines,

2nd edition, 1912, pp. 302-313. : :
Schaller, Waldemar, T., ‘‘Mica in 1917,”’ U.S.G.S., Mineral resources, 1917, pt. IT.

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