6? 
mineralogy. 
SEC t. LX. 
The Sardonyx. 
Is a mixture of the chalcedony and cor- 
nelian, fometimes ftratum-wife, and fome- 
times confufedly blended and mixed toge- 
ther. 
a. Striped with white and red ftrata : this 
ferves as well cut in cameo as the onyx. 
#. White, with red dendritical figures. 
This very much relembles that agate 
which is called the Mocha ftone, but with 
this difference, that the figures are of a 
red colour in this, inftead of black, as in 
that agate. 
I have unwillingly diftinguiftied the 
onyx, cornelian, chalcedony, fardonyx, 
and agate, as feparate fpecies, fince there 
is no real difference between them, except 
fome inexplicable degrees of hardnefs ^ 
' but I have been induced to continue thefe 
names for the reafons before given in 
ped. liv. 
SECT. LXL 
The Agate, Achates, 
This name is given to flints that are va- 
riegated with different colours, promifcuouflv 
blended together; and they are efteemed 
in proportion to their mixture of colours, 
their beauty and elegance. Hence alfo they 
have obtained variety of names, mofliy 
Greek, as if the bufmefs of the lapidary in 
cutting of them, and admiring their fevefal 
beauties and figures, had been derived from 
^h^t nation alone. 
Fa As 
