d'oeuvre, whose engraver has been inspired by Michael Angelo.
This
stone was in the cabinet at Versailles, and was one day swallowed by an
enthusiast in gems; but fortunately Hardion, who was exhibiting the
treasures, observed the act, and before the honest man departed
persuaded him to take an emetic for the benefit of his stomach. The gem
was in this manner immediately recovered.
SECOND CLASS. THE ZIRCON.
The
zircon, called also the jargon, is altogether special in its
composition, being formed of silica, united with a peculiar
mineral—zircona, the oxide of zirconium.
The zircon crystallizes in four-sided prisms, with various modifications. Fig. JJ shows the primitive form, and Fig. 78 a modification approaching the form of the dodecahedron.
Generally
speaking, each of the two types has its own particular colour, which is
shared by the crystals belonging to it. The first is a brownish and
greenish-yellow, the second brownish-red. Werner called the rhomboidal
type hyacinth, and the prismatic zircon. Ancient lapidaries made the same
