AS 
TAB. CCXXIII. 
SILEX §steatites; var. indurata. 
Indurated Steatite. 
Perrnars this substance may have so much resembled 
Porcelain, that when polished it might be mistaken for na- 
tural Porcelain, and it may possibly be very nearly the 
same in regard to the component parts, especially with that 
which is made of Petuntse and Kaolin. The present specimen 
from Portsoy must be allowed to be softer than the Porcelain, 
but would nevertheless become harder by being heated. It 
is chiefly composed of Silex, Alumine, and Magnesia, like 
the last substance, but in a harder state, and the tints may 
give a lesson for a new way of preparing colours, if that 
were necessary, and may indeed be useful, though the 
colouring of Porcelain is now tolerably perfect. ~The co- 
lours in this seem chiefly to depend on Oxide of Iron in 
different states; thus the yellowish hue is owing to a 
mixture of a pale yellow Oxide in” a small quantity, and 
the red to a mixture of very deep Oxide of Iron; but the 
green may arise from a mixture, as it were, of Chlorite. | 
This is sometimes intimately mixed with Steatite, and is 
curiously dispersed ‘about the present specimen in lines, 
spots, &c. Indeed these and the larger yellower spots are 
nearly the same in appearance with the Hatchet Stone of 
the Leeward Islands, called Nephrite, Jade, &c.; but 
