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MINERALS AND GEOLOGY 



forming schistose beds or chloritic iron slates. Also in sub-folia 

 or more or less compact and sectile beds, of economic value as pot- 

 stones in Bolton and Broughton. In the form of chloritic rock- 

 masses this mineral is especially characteristic of Huronian strata, 

 and is thus largely present throughout the wide extent of country 

 north of Lake Huron and Lake Superior. 



81. Chloritoid : Greyish-green, greenish-black, dark grey, In 

 thin lamellar masses, and also, occasionally in imbedded nodules of 

 foliaceous texture. H=5.5 6.0 ; sp.gr. 3.5 3.6. BB, in the 

 outer flame, becomes red ; in the inner flame, dark and magnetic ; 

 but resists fusion, or vitrifies only on the thinnest edges. Yields 

 water in the bulb-tube. Decomposed by sulphuric acid. A dark, 

 greenish-grey variety from Leeds, analysed by Dr. Sterry Hunt, 

 yielded : silica 26.30, alumina 37.10, protoxide of iron 25.92, pro- 

 toxide of manganese 0.93, magnesia 3.66, water 6.10. Occurs in 

 many of the schistose strata of the Eastern Townships, more es- 

 pecially in Brome and Leeds. 



Loganite (Altered Hornblende) : This substance is derived apparently from 

 the alteration and partial decomposition of hornblende (No. 52, above). It 

 occurs in small dull brown crystals, resembling those of hornblende, in the 

 crystalline limestone of Calumet Falls on the Ottawa, associated with serpen- 

 tine, phlogopite and apatite, H about 3.0 ; sp. gr., according to Hunt, 2.60 

 2.64. Infusible. Partially attacked by acids. Dr. Hunt's analysis shewed: 

 silica 33.28, alumina 13.30, magnesia 35.50, iron peroxide 1.92, volatile matter 

 (water, &c.) 16.00. 



Hydrous Diallage : This is also a product of alteration, derived apparently 

 from augite (No. 53, above). It occurs in cleavable masses of a greenish-grey 

 or pale green and somewhat waxy lustre, associated with apatite, calcite and 

 sphene, in crystalline limestone in North Elmsley, and also in association with 

 phlogopite in North Burgess. H = 1.5 3.0; sp. gr. =2.3 3.55. Infusible, 

 or nearly so. Composition somewhat variable, but essentially, after Hunt's 

 analysis: silica 36.50 39.70, alumina 10.8014.80, magnesia 25.6228 26, 

 iron protoxide, 4.329.54, water 14.017.66. 



Another variety, in greenish and somewhat pearly masses with H=5.0 and 

 sp. gr. about 3.0, from the Eastern Township of Orford, yielded Dr. Sterry 

 Hunt: silica 47. 10, alumina 3.50, magnesia 24.58, lime 11.34, iron protoxide 

 8.55, water 5.5. It is related apparently to the hydrous bronzite described 

 below. 



Hydrous Bronzite : Also an alteration product, derived apparently from 

 augite. Occurs in bronze coloured cleavable and scaly masses in schistose 

 strata in the township of Ham. Dr. Hunt's analysis gives : silica 50.00 

 magnesia 27.17, iron protoxide 13.90, lime 3.80, water 6.30. 



