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Eaft Indies , and fometimes in Europe : the Oriental 
are the fineft ; but the Bohemian , neverthelefs, very- 
beautiful. It is often found among the Earth of 
Mountains, on the Banks of Rivers, and bedded 
in Jafper. 
Ocuius Cati , the Cat’s Eye, by fome called Afte- 
ria, is of the Nature of an Opal, but harder, and 
Thews only two Colours, brown and white, the 
brown Teeming to be the Ground, and the white 
playing about it in the fame Manner the Fire Co¬ 
lour does in the Opal. This Stone takes a fine 
Polifh, but is ufually worn in its natural State: its 
Form is for the moft part that of the half of a fmall 
bifedted Globe, being fiattifh on one Side, round 
on the other. It is found in the Eafi and JVeJi In¬ 
dies, and fometimes in Europe , and has been often 
ranked among the Sapphires. 
Eurcois. This was long thought to be a natural 
Gem-, but it has fince been difcovered to be in reality 
the Bone of an Animal by Accident fallen into a Cop¬ 
per Mine, whence it derives its ftony and mineral 
Qualities: it has not that fine blue Colour when 
firft found, requiring fome Art to bring it to Per- 
fedtion, and when done it does not for any length 
of time continue, but becomes gradually green ; 
which is the Reafon of its not being fo valuable as 
it would otherwife be : whilft it holds its Colour it 
is indeed a moft beautiful Stone. 
Oculus Mundi is of a pale and uniform Colour, a 
whitilh grey, noways varied ; it is almoft entirely 
opake, and does not take a good Polifh : when put 
into Water for a fmall Space of Time, it becomes 
confiderably tranfparent, and takes the Colour of 
the yellow Cornelian, or rather Amber, that is, a 
very fine bright pale yellow; but it retains this 
Beauty only whilft in the Water, taking when dry 
