Corundum

(n.) The earth alumina, 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.

卡洛斯录入

• The Eastern nations have used corundum for this purpose for ages. 威廉·亨利·杜利特. 世纪发明.
• Knight says: The corundum stone used by the Hindoos and Chinese is composed of corundum powdered, two parts; lac resin, one part. 威廉·亨利·杜利特. 世纪发明.

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