380 DR T. THOMSON on Asbestus, Chlorite, and Talc. 



The texture was foliated and curved, and the folia were ra- 

 ther thick. 



Lustre pearly, or between pearly and resinous. 



Slightly translucent on the edges. 



Feel soft. Rather sectile. 



It does not scratch calcareous spar ; but it scratches sulphate 

 of lime very readily. 



Has an earthy smell when breathed on. 



Specific gravity 2.512. 



Its constituents were found to be, 



Silica, ...... 39.524 



Magnesia, .... 35.080 



Protoxide of iron, . . 11.528 



Alumina, . . . . . 6.200 



Volatile matter (water ?) 8.120 



100,452 



It is obvious at a glance that this mineral differs entirely in 

 its contitution from talc. Its atomic constituents are very near- 

 ly, fciiww Lratiffi 9& te djfeift* oiL-ttu! ari 



7 atoms silica, 



5 atoms magnesia, 



1 atom protoxide of iron, 



1 atom alumina, 



1 $ atom water. 



Hence it consists of simple silicates, and is obviously a com- 

 pound of, 



5 atoms silicate of magnesia, 



1 atom silicate of iron, 



1 atom silicate of alumina, 



1 atom water. 



