15 
and bevilled edges; various hemitropic crystals saloon. 
or macles of diamonds, &c. With these are also Nat. Hist. 
placed specimens of the alluvial rocks in which 
the diamonds occur in the East Indies and in 
Brasil .—Zircon : to which belong the common 
jargon of various colours, and the orange-colour¬ 
ed, considered by some as the true hyacinth , 
from Auvergne, Chili, &c. ; also the variety call¬ 
ed zirconite, from Friedrichsvarn in Norway, im¬ 
bedded in syenite, a rock composed of feldspar 
and hornblende .—Corundum : which compre¬ 
hends the precious stones commonly called ori¬ 
ental gems (the sapphire, ruby, oriental amethyst, 
oriental topaz, oriental emerald), of the crystal¬ 
line forms of which the principal modifications are 
here deposited; and the common or imperfect 
corundum from Bengal, Mysore, China (the dia- 
mantspath of Werner), Lapland, Piedmont, &c. 
•—As appendix to these are added, the jibrolite 
(bournonite of Lucas), one of the concomitant 
substances of common corundum ; and the emery 
which owes its hardness and consequent useful¬ 
ness in polishing to an admixture of blue corun¬ 
dum. Between the common corundum of this 
and the feldspar of the contiguous opposite table- 
case, is placed the andalusite , which was first 
considered as a congener of the former, and 
afterwards referred to the latter (as feldspath 
apyre ), but appears to be distinct from both. 
(Cases 3,4.) Among the many varieties of spinel 
we 
