110 Canadian Record of Science. 



of a fibrous mineral, as above described, and partly of a 

 clear one, which often affords rather rich polarisation tints, 

 and presents some resemblance to quartz. Its precise 

 nature is difficult to determine, owing to the absence of 

 distinctive characters, but I believe it to be of secondary 

 origin. Rock fragments are not common in the first 

 (interior) specimen (vii) ; one, however, is probably an 

 altered shale, and another possibly a limestone. This is 

 bordered by a pale pyroxenic mineral piercing into the 

 grains of calcite. In the second specimen (vi) fragments 

 are rather common : among them are those of diabase, 

 ranging from fine to coarse, one speciuien of the latter, 

 originally, perhaps, an inch in diameter, showing an 

 ophitic structure ; felspar and augite both being rather 

 altered, seemingly by infiltration, and one small fragment 

 resembles a subcrystalline limestone. Specimen (v) does 

 not materially differ, but seems to contain more carbonate 

 than the others. The dark streaking is due to grains of 

 iron oxide or serpentine with much opacite ; rock frag- 

 ments few and small. Specimen (iii) from the thin vein 

 contains a very few small rock fragments, mudstone, or 

 shale, more or less altered, possibly also a compact dia- 

 base. The " country rock " is a mudstone, consisting of 

 small chips of quartz and felspar, variable in size, em- 

 bedded in a dusty matrix, including a carbonate, which is 

 more abundant within about a fiftieth of an inch from the 

 junction. Tlie part is slightly stained, but I was unable 

 to detect any signs of contact metamorphism. Specimens 

 (ii) and (iv) are generally similar, but the former contains 

 some small rounded bits of varieties of diabase, and one 

 may represent a crystalline limestone. The veins are 

 filled with calcite and other secondary products, and are 

 bordered by a very thin film of a brown micaceous mineral, 

 like that desciibed as often permeating the " blue." Both 

 specimens suggest micro-mineralogical changes, such as 

 might be produced by the passage of hot water. 



