218 REVIEWS THE ECONOMIC MINERALS OF CANADA. 



*' 1. Walton Quarry, Melbourne, lot 22, range 6. .. .Benjamin Walton, Montreal. 

 " a. Specimens of roofing slate. 



" This band of slate is in immediate contact with the summit of the serpen- 

 tine. It has a breadth of one-third of a mile, and dips about S. E.<80°. Mr. 

 Walton commenced opening a quarry upon it in 1860, and found it necessary, 

 in order to gain access to the slate, to make a tunnel through a part of the 

 serpentine. To complete this, and to expose a suflScient face in the slate to 

 pursue profitable working, has required two years of time, and $30,000 of 

 expenditure. The face now exposed has a height of seventy-five feet ; but the 

 band of slate crosses the St. Francis and the fall from the position where the 

 quarry is now worked, to the level of the stream, is upwards of 400 feet, the 

 distance being one and-a-half miles, so that by commencing an open cutting oa 

 the slate, at the level of the stream, a much greater exposure can be ultimately 

 attained. Up to a comparatively recent period, the^ usual coverings of houses 

 in Canada have been wooden shingles, galvanized iron or tin-plate, but so many 

 destructive fires have occurred from the use of the first of these, that they 

 are now interdicted in all large towns. Slate, as a covering, costs about one- 

 third more than shingles, but one-half less than tin, and one-third less than 

 galvanized iron. 



" The quarry has now been in operation since the spring of 1861 ; 2000 squares 

 have been sold, and some of the slates have been sent to a distance of 550 miles 

 from the quarry ; a quantity of them having been purchased for Sarnia on the 

 River St. Clair. To show that slate, as a covering, is well adapted to resist the 

 influences of a Canadian climate, it may be here stated that slates from Angers 

 in Prance, have been exposed on the roof of the Seminary building on the 

 corner of Notre Dame and St. Francois Xavier Streets, in Montreal, for upwards 

 of 100 years, without any perceptible deterioration. The strong resemblance 

 between these and the slates of Melbourne, as well as those from Bangor in 

 Wales, may be seen in the following comparative analyses by Mr. T. Starry 

 Hunt :— 



Welsh. French. Melbourne. 



Silica 60.50 57.00 64.20 



Alumina 19.70 20.10 16.80 



Protoxyd of Iron 7.83 10.98 4.23 



Lime 1.12 1.23 0.73 



Magnesia 2.20 8.39 3.94 



Potash 3.18 1.73 3.26 



Soda 2.20 1.30 3.07 



Water 3.30 4.40 3,40 



100.03 100.13 99.63 



The proximity of the serpentine leaves no doubt as to the geological horizon 

 of these slates. — Quebec Group, Lower Silurian. 



These quotations will sufficiently illustrate the character of the 

 information afforded. Its extent and variety can only be understood 



