19G Common Roclcs of the British Fro'cinces, 



ARTICLE XXXII.— O/i some of the Common Rods of the British 



Provinces. 



The student of nature in the country, who must depend upon reading- 

 and his own observation for the acquisition of a knowledge of the science of 

 geology, should first learn to recognise those minerals and rocks which are 

 the most abundant, and afterwards proceed to the study of those more rare. 

 In the following article we shall point out a few of the former, and give some 

 general accounts of then- distribution compiled from such sources as we have 

 at our command. 



There are a few simple minerals which, by their various combinations, 

 constitute the principal part of all the rocks visible upon the surface of the 

 earth, and when a person has learned to know these at sight, he has made an 

 important progress in practical geology. Thousands of square miles of the 

 British Provinces are covered with masses of rock composed altogether of 

 the five minerals, (juartz, felspar, mica, hornblende, and carbonate of lime. 

 The latter constitutes aU the limestone of the country, while of the other four 

 are composed nearly all those hard rocks, usually, but incorrectly called granite, 

 which may be seen in the hilly regions on the northern frontier of the settle- 

 ments, extending from the mouth of the St. Lawrence to the Georgian Bay. 

 Granite is comparatively rare throughout the greater portion of Canada, 

 although another rock which closely resembles it, and is composed of the 

 same ingredients, is the most abundant of all, either in mountain masses or 

 strewn in rounded boulders or angular blocks over the surface. This latter 

 is gneiss, of which there are many varieties, all however composed principally 

 of quartz, felspar, hornblende, and mica, combined in very variable propor- 

 tions. Of this rock, we shall give a more particular account hereafter. 



Of the minerals above mentioned, quartz is one of the most common, 

 and forms one of the principal ingredients in the structure of the hard crust 

 which constitutes the exterior covering of the earth. It is generally of a 

 white colour, and sufficiently hard to scratch glass or give fire with steel. — 

 In fact, all the gun-fiints once in use consist of a greyish or blackish variety 

 of quartz. The fragments of white mineral often picked up in the fields and 

 used for striking fire are quartz. Grains of quartz of greater or less size, 

 and often veins of it, may be seen in nearly all the boulders near the southern 

 margin of the Laurentine formations, while the great masses of rock which 

 constitute the rugged hills of those portions of the Province where this 

 extensive formation prevails, have often one fourth of their whole bulk 

 composed of it. 



Although the most common colour of quartz is milk white, yet it is often 

 perfectly transparent or of various shades of white, yellow, red, or violet, ar,d 

 it is variously called granular quartz, smoky quartz, fetid quartz, brovm 



