526 A POPULAR EXPOSITION OF THE 
nowhere, apparently, in very prominent specimens. Mr. Murray, in 
his report for 1858, cites the east shore of Portage Harbour, Lake 
Huron, as a locality of this mineral. 
Hornblende.— Dark or light-green, black, brownish, and sometimes 
light-grey or colourless. In prismatic crystals (of the Monoclinic 
System) figs. 39 and 40, or more frequently in amorphous masses of 
a fibrous or lamellar structure. The dark varieties are commonly 
known as Hornblende or Amphibole; the bright or light-green 
varieties, as Actynolite; and the greyish or colorless varieties, as 
Tremolite, II. 55-60; sp. gr. 3°0-3'4. Hasily fusible, the dark 
specimens yielding magnetic beads. Composi- 
tion: silica and magnesia, the Jatter in part 
replaced by protoxide of iron or lime; alumina 
being also sometimes present. This mineral 
forms one of the essential components of many Fig. 39. _—“Fig. 40. 
metamorphic and eruptive rocks. It thus occurs in syenitic gneiss, 
hornblende-slate, &e., throughout the large area occupied by the Lau- 
rentian strata, and in the intrusive syenites associated with these—as 
in the township of Grenville, Argenteuil county, C. E., and other 
localities. It occurs also in crystals and fibrous masses in the beds of 
crystalline limestone belonging to this series. Amongst other Lauren- 
tian localities, we may enumerate, Grand Calumet Island (Tremolite, 
&e.) ; Blasdell’s Mills, river Gatineau; Grenville, &c.,—in Canada 
East; with the neighbourhood of Verth, &c., in Lanark County, 
C. W. (the acicular variety termed ‘‘ Raphilite’’) ; Elzevir township, 
Hastings County (dark-green, and in places, black fibrous masses 
which have been taken for coal); Barrie and other townships in 
Frontenae County ; the Muskoka river, the Falls of the Madawaska, 
&c.,—in Canada West. In the more modern metamorphic district 
south of the St. Lawrence, hornblende occurs largely as a rock con- 
stituent, as in Beauce and other counties. Also in crystals and 
crystalline grains in the eruptive masses of Shefford, Belwil, &c., of 
that district. 
Augite.—This mineral in colour and all general characters, as well 
as in composition and blowpipe comportment, closeiy resembles 
Hornblende. The crystals belong likewise to the Monoclinic Sytem, 
but differ in aspect, as shown. by fig. 41, one of the most common 
combinations. The front prism-angle (and the angle of cleavage- 
