68 



coarse-grained, biotite granite, with a characteristic pink 

 color. At Kirk lake it invades the Keewatin greenstone, the 

 Keewatin iron formation (Grenville series), the Temiskam- 

 ing sediments and the lamprophyre dikes. Whether some 

 of the quartz and feldspar prophyries, described under the 

 Keewatin series, are genetically connected with the Lorrain 

 granite is not as yet known. The granite is overlain uncon- 

 formably by the Cobalt series. Its relative age is therefore 

 accurately known. Where it invades the adjacent form- 

 ations it sends out in every direction many fine-to-medium- 

 grained aplite dikes. In hand specimens these dikes are 

 similar to some of the aplites which are the end phase of the 

 Nipissing diabase. The latter dikes, however, contain only 

 small quantities of potash, while the granite aplites at Kirk 

 lake have normal percentages of soda and potash, as will be 

 seen from the analyses given below. The intrusion of the 

 Lorrain granite was probably the means whereby the Temis- 

 kaming sediments were tilted up into their present more or 

 less vertical position. Near the contact the intrusion has 

 sometimes developed garnets in the adjacent rocks. 



Analysis No. I, given below, is from the coarse-grained 

 parts of the granite, while No. 2 is from the aplite dikes a 

 few inches in diameter. In each case about a dozen speci- 

 mens were taken in order to arrive at average results. 



Si0 2 



FeO 



Fe 2 0, 



A1 2 



CaO 



MgO 



Na o 



K„6 



H 2 



100.38 100.47 



While the Lorrain granite has been intruded by the 

 Nipissing diabase, silver-cobalt deposits of importance have 

 not been found in it. That silver is rapidly deposited on 

 the surfaces of or in cracks in the granite is shown bv the 



I 



2 



71.86 



76.03 



2.34 



1.29 



173 



1.44 



15.11 



13.02 



■51 



•15 



■43 



.16 



370 



3.68 



348 



374 



1.22 



.96 



