MINERALS AND GEOLOGY OF CANADA. 153 
do not fuse. Common mica is essentially composed of silica, alumina, 
and potash; but other micas contain magnesia, oxides of iron, lithia, 
&c. Mica is a component of granite, of ordinary gneiss, mica slate, 
and other eruptive and metamorphic rocks, besides being of frequent 
occurrence in trachytes, lavas, &e. In Canada it occurs in more or 
less distinct specimens throughout the area occupied by our Lauren- 
tian rocks, and also in the metamorphic district of the Eastern 
Townships, both in the stratified-crystalline and in the trappean or 
trachytic rocks there present. Inthe erystalline limestone (Lauren- 
tian Series) of the township of Grenville, Argenteuil county, C.E., 
plates are obtained of sufficient size to be employed for stove-fronts, 
lanterns, &c. We possess some crystals of a yellowish-green colour, 
over half-an-inch in length, and perfectly translucent in a transverse 
direction or parallel with the cleavage-plane. They are imbedded in 
crystalline limestone and are said to have come from the Upper 
Ottawa. A lithia-containing mica, known as Lepidolite, in granular- 
scaly masses of a pink or reddish-grey colour, and pearly lustre, 
occurs in Maine, and elsewhere in the United States, but has not 
been found, as yet, in Canada. It fuses very easily and with con- 
tinued bubbling, tinging the flame red. 
Tale (certain varieties.)\—In white or greenish foliated massea, 
somewhat unctuous to the touch, and yielding readily to the nail. 
Most varieties give off water when heated, and hence this mineral 
is described more fully under division D 5 below. 
Asbestus.—In soft, fibrous, and more or less flexible masses, of a 
green, white, or other colour. Easily fusible. See under Horn- 
blende and Augite, C3, above. (Vol. V., p. 527.) 
§ 2, EFFERVESCING STRONGLY IN Coup Acrps. 
Calcite or Cale Spar.—Of all colours—white, grey, yellow, black, 
&c., with white streak. Occurs in lamellar, fibrous, and granular 
masses, in stalactites, &c., and in crystals of the hexagonal system, 
some of which are shewn in the accompanying figures. Cleavage 
strongly marked in three directions, producing a rhombohedron of 
105° 5’ and 74° 55’,—fig. 47 a. H.3°0; sp. gr.2°5—2°75. Infusible, 
but glows strongly before the blowpipe, and becomes caustic. Soluble 
with effervescence in acids. Composition: carbonic acid 44, lime 56 ; 
but a small portion of the carbonate of lime is generally replaced by 
carbonate of iron or magnesia, This substance, in the form of rock 
