100 



MINERALS AND GEOLOGY 



FIG. 61. 



48. Vesuvian or Idocrase : Yellow, brown, yellowish-red, &c. 

 Tetragonal in crystallization : otherwise, both in composition and 

 general characters, identical with garnet. H = 6.5 ; sp. 



gr. 3.3 3.45. BB, more or less readily fusible. Occurs 

 in some of the crystalline limestones of the Ottawa Dis- 

 trict : principally in brown crystals, with tourmaline, at 

 Calumet Falls, and in the township of Clarendon ; and 

 also in small reddish-yellow crystals, with zircon, py- 

 roxene, graphite, &c., in the township of Grenville. 



49. Epidote : Green, yellowish-green, blackish-green, grey, <kc. 

 Monoclinic in crystallization, but well denned crystals are of rare 

 occurrence in Canada ; mostly in acicular crystals, and in columnar, 

 reniform and more or less compact masses, or in imbedded grains. 

 H = 6.07.0 ; sd. gr. 3.25 3.35. BB, swells up and forms a dull 

 slag-like mass, with rounded edges. This is generally magnetic, 

 but unlike the beads formed by hornblende, pyroxene, vesuvian, &c., 

 it resists further fusion. After strong ignition, epidote gelatinises 

 in boiling hydrochloric acid. (See under " Action of Acids," in 

 Part I.) General composition : silica 34 40, alumina 18 28, ses- 

 quioxide of iron 7 17, lime 20 25. This mineral is comparatively 

 rare in the Laurentian rocks of Canada, but it occurs, although with 

 more or less indistinct characters, in the gneissoid strata associated 

 with the iron-ore of Belmont, Seyour, and Marmora ; and in irregular 

 layers in a reddish gneiss at Carleton Place, in the township of Beck- 

 with, Lanark County, the rock, when polished, forming a handsome 

 ornamental stone. Epidote is far more abundant in the metamor- 

 phic stiata of the Eastern Townships, and it occurs thus in St. 

 Armand, Potton, Shipton, Melbourne, and elsewhere throughout 

 that region. Some of the best defined examples are found in spheroi- 

 dal masses of a peculiar slate-rock in the seignory of St. Joseph, the 

 epidote in these masses being associated with calcite, serpentine, 

 chlorite, and quartz. Epidote occurs also in some of the amygdaloi- 

 dal traps and greenstones of Lake Superior, as at Maimanse (with 

 mesolite, chlorite, brown garnet, &c.), and on the Island of Michi- 

 picoten. 



50. Allanite (Orthite) : Black, brown, yellowish-brown. Mono- 

 clinic, and like Epidote in crystallization, but occurring generally in 

 granular and amorphous masses, with strong resino-vitreous lustre. 





