OF CENTRAL CANADA PART II. 117 



(10) GROUP OF TALCOSB SILICATES. 



[The minerals of this group are essentially non-aluminous mag- 

 nesian silicates, foliated or compact in texture, very sectile, and more 

 or less greasy or soapy to the touch.] 



82. Talc, including Steatite or Soapstone : Silvery or greenish- 

 white, pale-green, greyish ; often mottled in grey and greyish tints. 

 Hexagonal in crystallization, but occurring mostly in foliated or scaly 

 masses, the folia flexible but not elastic (Talc}, or in beds of a sub- 

 granular, slaty or compact texture (Steatite or Soapstone). Very 

 sectile, and more or less soapy to the touch. H=1.0 2.0 ; sp. gr. 

 2.56 2.8. BB, sometimes exfoliates, but melts only on the thinnest 

 edges. In the bulb-tube, yields, generally, a little water. Scarcely 

 attacked by acids. Average composition ; silica 63, magnesia 33, 

 water 4 ; but some specimens contain merely a trace of water, whilst 

 others yield 6 or 7 per cent. Talc appears to be of rare occurrence 

 in the more ancient metamorphic rocks of Canada, but abed of grey 

 and dark greyish-green steatite, mixed with magnesian carbonate of 

 lime occurs near the village of Bridgewater in Elzevir, County of 

 Hastings. It is also said to have been found in Galway or Somer- 

 ville. In the higher metamorphic strata south of the St. Lawrence, 

 talcose slates, on the other hand, are not uncommon, and beds of 

 steatite are comparatively abundant. These lie principally in the 

 townships of Bolton, Sutton, Potton, Stanstead, Leeds and Vaudreuil. 

 As shown by Dr. Sterry Hunt, they frequently contain traces of 

 oxide of nickel, A bed of mottled and pale-green steatite of excel- 

 lent quality has been found recently by Mr, Peter McKellar near 

 Thunder Bay, on Lake Superior. A specimen analysed by the 

 writer, yielded : silica 62.67, magnesia 33.40, oxide of iron 0.86, 

 water 1.88. The more compact kinds of steatite are capable of 

 economic employment in the manufacture of fire-bricks, stoves, 

 baths, gas burners, culinary vessels, table ornaments, &c., and other 

 varieties are used as a paint material. Powdered talc or steatite 

 appears also to be occasionally added to ordinary lead paint with a 

 view to produce increased lustre ; and it has been employed to lessen 

 friction in machinery. 



Pyrallolite or Renselaerite : This substauee agrees essentially in composition 

 and general characters with steatite, but presents the cleavage and occasionally 

 the crystalline form of augite. It is evidently a product of alteration. Mostly 



