MINERALS AND GEOLOGY OF CANADA. 529 
Albite or Soda Feldspar.—This mineral closely resembles common 
feldspar in colour and general characters, but differs in belonging to 
the Triclinie System, and by containing soda in place of potash. Its 
cleavage planes do not meet at right angles, but at inclinations of 
93° 36 and 86° 24’, It enters generally into the composition of 
trap rocks, and replaces the orthoclase of some granites and syenites. 
In Lanark County, C. W., a beautiful iridescent variety, the so-called 
** peristerite,” is met with. 
Labradorite or Lime Feldspar.—Chiefly light or dark grey, greenish, 
or lavender-blue, with frequently a beautiful reflection of green, blue, 
orange, and other colours. Commonly in cleavable, lamellar masses, 
the cleavage planes (one of which is usually striated) meeting at 
angles of about 933° and 865°. H.60; sp. gr. 2:67-277. Some- 
what easily fusible in thin splinters. Composition: essentially— 
silica, alumina, and lime, with a portion of the latter replaced by 
soda. Labradorite (or a mixture of various triclinic feldspars,) forms 
one of the metamorphic rocks of the Laurentian series, interstrati- 
fied with the gneissoid and other crystalline rocks of that age. Fine 
examples of the mineral occur in Lanark County, OC. W.; and in St. 
Jérome, Morin, Abercrombie, and the seignory of Mille Isles, in 
Terrebonne County, C. EH. Many of these examples are (externally) 
opaque-white, by weathering. Boulders containing opalescent feld- 
spar masses, occur also abundantly in Grenville, &c., in the neigh- 
bouring County ot Argenteuil.* Labradoritic rock (a mixture, 
according to Mr. Hunt, of labradorite and andesine,) occurs also in 
the parish of Chateau Richer in Montmorency County, C. BE. ; and 
opalescent specimens are cited from islands off the north-east shore 
of Lake Huron. 
Note.—Mineralogists have established under the names of Anorthite, Andesine, Oligoclase 
&c., various additional species of lime feldspar. These are triclinic in crystallization, and 
more or less closely related. As a general rule, indeed, they are only to be distinguished by, 
accurate chemical analysis. Practically, they may be classed with Albzte or Labradorite. 
To Anorthite, the so-called Bytownite is referred, This is 2 greenish-white feldspathic 
mineral, found in boulders about Ottawa city. Another smoky or greenish-blue mineral, of 
a somewhat feldspathic character, from Perth, Canada West, is referred also to the same 
species. 
Scapolite or Wernerite.—White, greenish, reddish, &c. Chiefly in 
lamellar and fibrous masses, and in crystals of the Dimetric System, 
* A beautiful vase worked from one of these boulders may be seen in the Museum of the 
Geological Survey in Montreal. 
