CORUNDUM n.
umina, as found native in a crystalline state, including sapphire, which is the fine blue variety; the oriental ruby, or red sapphire; the oriental amethyst, or purple sapphire; and adamantine spar, the hair-brown variety. It is the hardest substance found native, next to the diamond.
CRYSTAL n.
under Blood. -- Compound crystal. See under Compound. -- Iceland crystal, a transparent variety of calcite, or crystallized calcium carbonate, brought from Iceland, and used in certain optical instruments, as the polariscope. -- Rock crystal, or Mountain crystal, any transparent crystal of quartz, particularly of li…