97 
SHALE AND SLATE. 
Shale is a fine textured argillaceous rock of sedimentary 
origin. It splits into thin fragments parallel to its bedding. 
Slate is also an argillaceous rock of fine texture. It has 
been subjected to lateral pressure which has developed cleavage 
planes at right angles to the direction along which the pressure 
acted, permitting it to be broken readily into thin slabs. 
USES. 
Soft shales are frequently ground and used for brick-making. 
Large quantities are used in a number of localities in Canada 
for this purpose. No record of quantities is available. 
Slate is used as a roofing material. It is split into thin 
sheets and trimmed to convenient dimensions. There is only 
a small market in Canada for slate shingles, as they do not 
withstand the effect of our severe winters satisfactorily. It is 
a lso used to make electric switchboards, school slates, and 
blackboards. 
Crushed slate or shale is used for making “ready roofing.” 
L°r this purpose it is crushed to about one-eighth or one-quarter 
inch size. 
When ground very finely these rocks are used as filler for 
Wood. Paint manufacturers prepare wood-filler by mixing the 
ground material with oil. 
PRICES. 
The price of finely ground shale or slate ranges from $9 
to $23 per ton. 
Amount of ground slate and keystone used in the manu- 
fact 
nnng industries, as reported by the consumers:— 
Location 
Quebec" 16 Provinces - 
Ontario.’ 
Brie ^ Provinces, 
ntish Columbia. 
Canada 
No. of firms 
reporting 
consumption 
10 
Domestic 
Tons 
Imported 
Tons 
221 
239|g