IOO 



INTRODUCTION. 



The purpose of this excursion will be to examine the 

 character and mode of occurrence of the asbestos and 

 chromite deposits of Quebec, and to observe the methods 

 of mining. At Thetford and Black Lake the asbestos 

 occurs in an igneous intrusion of stock-like proportions, 

 while at East Broughton it occurs in a sheet or sill. The 

 most typical deposits of chromite will be examined at 

 Black Lake. 



The district yields over three quarters of the world's 

 supply of asbestos, with an annual value, at present, of 

 about $3,000,000. 



The first geological work in the asbestos district was 

 carried on under Sir William Logan prior to the discovery 

 of the more important bodies of asbestos bearing rocks. 

 Sir William drew attention to the economic possibilities 

 of these rocks, and gives a large amount of general informa- 

 tion about them in his "Geology of Canada, 1863." 



Subsequent reports of the Geological Survey of Canada 

 added to this information, the next important advance 

 being the reports by R. W. Ells in 1886 and 1888, which 

 give the results of more detailed mapping after the develop- 

 ment of active mining. In 1903 a Bulletin on Asbestos 

 was published. 



A monograph by Fritz Cirkel was issued by the Mines 

 Branch in 1905, which describes the occurrence, uses, and 

 methods of mining and concentrating asbestos. Chromite 

 was also treated in a similar manner in a further report by 

 Cirkel in 1909. Both these volumes deal more especially 

 with the mining side of the subject, the geology receiving 

 relatively much less attention. 



In 1907 a detailed examination of the serpentine belt 

 in which the asbestos and chromite deposits occur was 

 begun for the Geological Survey by J. A. Dresser. His 

 reports of progress, appearing in the Annual Summary 

 Reports of the Geological Survey for 1907, 1909 and 1910, 

 give the fullest accounts of the geology of these deposits 

 yet published. The general description of the asbestos 

 producing area which follows is taken nearly verbatim 

 from Dresser's Summary Report for 1909. 



