276 REGINALD E. HORE 



greenish ones contain a fibrous chlorite. Frequently the aplites have 

 a considerable percentage of finely crystalline calcite, and small crys- 

 tals of titantite and grains of epidote are common. The quartz and 

 feldspar are usually in equidimensional grains as typical in aplites, 

 while occasionally there are micrographic intergrowths, and in some 

 specimens rounded grains of feldspar in a matrix of later-formed 

 quartz. Analysis by N. L. Bowen of a specimen from one of these 

 veins is given in the table on p. 275 (anal. No. 6).' 



On the property of the University Mine in Coleman Township is a 

 larger fissure-filling, exposed at intervals for eight hundred feet, and 

 in places over fifty feet wide. Analyses of specimens of this vein are 

 given in Columns 7 and 8. The specimen No. 7 is a fine-grained 

 gray soda granite taken from the wide part of the vein. The 

 specimen No. 8 was taken about three hundred feet from No. 7, 

 and is finer in grain and free from carbonates. Portions of the rock 

 contain a high percentage of calcite, which fills interstices between 

 the earlier-formed feldspar and quartz. 



Quartz and calcite veins. — The most common type of minor 

 fissure-fillings is composed of white quartz. Chlorite and fibrous 

 amphibole are common constituents and pyrite, chalcopyrite, and 

 galena are frequently present. In some of the quartz veins there is 

 considerable calcite filling interstices between well-formed quartz 

 crystals. 



Relation of the diabase and sodic aplitic veins. — In some large sills 

 there are portions, one to two hundred feet from the bottom, which 

 are pink, coarse grained, and more highly sodic than the gray, medium- 

 grained, main mass, into which they pass by insensible gradations. 

 Similar pink-colored rocks occur as irregular-shaped masses distinctly 

 marked off from the gray diabase. The microscopic examination 

 shows that the pink-textured portions have a higher percentage of 

 those minerals which were last to crystallize in the gray diabase. The 

 aplitic veins are composed almost entirely of the chief of these last- 

 formed minerals — sodic feldspar and quartz. 



There is a lack of evidence which would indicate any extensive 

 fusion and absorption of the intruded rocks. Xenoliths are not 



' N. L. Bowen, Canadian Mining Journal, April 15, 1909; see also Bulletin of 

 Canadian Mining Institute, December, 1909. 



