Notes on Asbestus. 103 



At the Thetford mines, also, there are found veins of a soft 

 white mineral. On exposure to the air it hardens but does 

 not acquire a waxy lustre, but has much the appearance of 

 unglazed white earthenware, arid absorbs water with avidity. 

 On analysis its composition was found to be : — 



Silica..... 43.191 



Alumina 1.463 



Ferrous oxide 293 



Magnesia 41.520 



Water 14.000 



100.467 



The Laurentian serpentine also contains seams of soft 

 silicates. A Montreal gentleman who determined to ascer- 

 tain the character of the Laurentian asbestus at some 

 distance from the surface, in blasting the rock at a point 

 some miles north of Lachute, met with a soft mineral, 

 in physical characters much resembling those already 

 described. The writer received a small sample which was 

 laid aside in a warm and dry room, and examined from 

 time to time. It gradually hardened, then crumbled to 

 powder. After two months of exposure to warm and very 

 dry air, it was found to lose no less than 6.05 per cent, mois- 

 ture at 100° C. In composition this mineral is closely 

 related to sepiolite or meerschaum, as the following analysis 

 shows : — 



Silica 61.585 



Carbonic acid 1 - 290 



Alumina 



Lime = 4.037 



Magnesia 25.980 



Water 6.600 



99.492 



Fragments of light greenish-yellow serpentine were scat- 

 tered through this specimen, whilst particles of a darker 

 variety are disseminated through the Thetford mineral and 

 through some of the material from Coleraine. 



Other minerals found associated with the asbestus are 



