Composition of Limestones and Dolomites 29 



Calciferous Formation. 



5. From the township of Rigaud, near to the Riviere a la 

 Graisse and also to the boundary line between Quebec and 

 Ontario. A hard rusty-weathering dolomite supposed to 

 be from the Calciferous formation. Its analysis gave : 



Calcium carbonate 39.91 



Magnesium " 32.85 



Alumina and ferric oxide. 3.56 



Insoluble matter , 23.54 



99.86 

 The insoluble portion contained, 



Silica 76.34 



Alumina and ferric oxide 14.74 



Lime 1.02 



Magnesia 7.99 



100.09 



6. McNab, Ontario, Range III, lot II. .A compact, dark 

 brownish-grey limestone with conchoidal fracture. It was 

 found to contain : 



Calcium carbonate 81 . 78 



Magnesium " 13.68 



The stone is somewhat fossiliferous and probably less 

 magnesian than the average material from the Calciferous. 

 It has been used for building purposes at Arnprior. 



1. McNab, Ontario, Range XIV, lot IX. From close to 

 the shore of Lac des CJiats on the Ottawa, and about two 

 miles above the mouth of the Madawaska. A compact 

 brownish-grey dolomite dotted with occasional crystals of 

 white calcite. A partial analysis gave : 



Calcium carbonate 53.00 . 



Magnesium " 43.88 



From the same set of beds as No. 6, but considerably 

 lowor in the formation. 



Chazy Formation. 

 8. Pembroke, Ontario, Range I, lot XII. Compact, light 



