r 44 ] 
veral diftin£l Species ; and for the mod part found 
in thofe Farts of the World that produce the Onyx, 
particularly the warmer and Eaftern Climates. 
In this Table alfo are many Specimens of the 
different Kinds of Jafper, of which fome Account 
has been given Page 37. 
And there is a rough Egyptian Pebble, which is 
broke ; on each Piece of it is a perfeft Refemblance 
of the Head of Chaucer , as he is ufually painted : 
this is quite the Work of Nature, not having been 
at all affifted by Art- 
Some Pieces of Lapis Lazuli , or azure Stone, by 
the Ancients called Cyaneus and Cceruleum. It is of a 
blue Colour, veined and (potted with white and 
yellow: it is not difficult to imitate it by Art; but 
the genuine good Stone Ihould be able to refift Fire 
and Smoke, and come forth with new Luflre •, of 
this is made Ultramarine. • It is found in Mines of 
Gold, Silver, and Copper, and more frequently in 
Pits of Marble, which lafl is that generally ufed. 
We next come to a great number of Specimens 
of precious Stones of all Kinds, opake and tranfpa- 
rent, rough and polifhed, fome loofe, others fet. I 
fhall give rhy Reader a few Remarks on the Nature 
of fome of them '; and begin with the 
Opal, fuppofed to be the Pyropus of Ovid ; this 
is the fofteft of all Gems, generally from the Size 
of a fmall Pea to a Horfe-bean, but fometimes 
larger than the Bean, and often fmailer than the 
Pea: its Colour is whitifh, or rather that of the 
finefl Mother of Pearl, but fo tranfparent that one 
may fee deep into the Stone : it is net eafy by De- 
feriptien to give an Idea of it; for, as it is turned 
about, it fhews almoft all Colours, as yellow, red, 
blue, green, purple, and a milky grey. It is pro¬ 
duced in Egypt, in Arabia, feverai Parts of the 
Eafi 
