216 



Others have supposed tta cracks to have been formed by the cooling 

 and shrinking of the mass from a heated and pasty state by which 

 cracks have been formed, which subsequently became filled with 

 asbestiform matter from below. In whatever way the fissures were 

 caused, and it is very probable that they have been formed by the 

 great processes of raetamorphism to which the rocks were exposed in 

 the change from dioritic matter to serpentine, the vein asbestus appears 

 more naturally to have been produced by a process of segregation 

 of serpentinous matter from the sides of the fissure, very much as 

 ordinary q artz in many mineral veins is known to have been 

 produced, the segregated or infiltrated matter gradually filling the 

 original fissure, and meeting at or near the centre, in proof of which 

 the presence of a comb of particles of iron is very often found occupying 

 the centre of the vein, and quite frequently these iron grains assume 

 sufficient size as to form a regular parting of iron ore in the fibre. In 

 this respect asbestus veins resemble very closely mineral veins with 

 quartz or calcite which frequently contain alternate layers of ore on 

 either side of a cential comb of crystals. The arrangement also of the 

 fibre at right angles to the sides of the containing fissure, except where 

 the rock has been disturbed, is confirmatory evidence in the same 

 direction. 



In some of the mines fibre of exceptional length is observed. 

 Sometimes there are veins caught along lines of fracture and drawn 

 out of their natural position. At other times this long fibre is, to 

 some extent at least, due to the friction of the r'ock walls by the 

 displacement of a fault. In this way the long woody fibred material, 

 known as hornblende to the miners, but which is rather a form of 

 picrolite, is probably produced. In the same position also, and due 

 probably to the same cause, are the long well fibred strips of asbestus 

 seen in some of the mines, and which at first sight might almost 

 be taken for vein matter of exceptional length. A very peculiar form 

 of asbestus is found on an island in Lake Nicolet, where also the 

 coarse picrolitic variety is well seen, which consists of small concretionary 

 pellets of asbestus containing a nucleus of serpentine and enclosed in a 

 steatitic rock. This peculiar development was first pointed out by Mr- 

 C. W. Willlmott, and has not been recognized at any of the other mines, 



