36 The Ottawa Naturalist. [May 



district, the amount of gold per ton of quartz of 2,000 lbs. being 

 stated at 11.725 ounces and of silver, 52.323 ounce.«. The size 

 of the sample from which this assay was made was small, and if 

 the vein from which the specimen was taken could be located 

 there would seem to be a prospect for further developments in 

 this direction. 



It may not be out of place here to suggest that the attempts 

 to obtain accurate information as to the quantity of gold con- 

 tained in the quartz veins, which traverse many of the rocks in 

 the Ottawa district, by mere assay of small samples is never 

 likely to prove satisfactory. This can only be done by submit- 

 ting a large sample of from one to three tons to a special mill 

 test. Such tests can now be readily made in the new mining 

 schools of Kingston or McGill college, and in this way definite 

 knowledge can be obtained as to the commercial value of the 

 ore, and the possibility of obtaining satisfactory lesults from its 

 extraction. 



It is very interesting to notice in connection with the occur- 

 rence of gold in this area that the same agencies which have 

 played so important a part in the development of the deposits 

 of mica and apatite, viz., that of intrusive granite or diorite, 

 have also been exerted here. Thus it has been clearly shown 

 that all the most productive mines are situated in close proxi- 

 mity tu igneous masses which have penetrated the country rocks, 

 generally composed of schists and slates, and it may be broadly 

 stated that the same general principle applies to all the valuable 

 mining areas both to the east and west. The productive 

 mineral zones of the Lake Superior district conform to this 

 general rule, and the deposits of copper and nickel at Sudbury 

 are also found in intimate associations with great intrusions of 

 granite and greenstone. It would therefore seem to be a well 

 established fact that these intrusive masses have exercised a 

 direct and favorable influence upon the presence of the economic 

 minerals. 



In the new group of mines on the Calumet Island, up the 

 Ottawa, the masses of blende and galena are always found con- 



