Also found in: Dictionary, Thesaurus, Medical, Financial, Acronyms, Wikipedia.
mineral, one of two crystalline forms of the element carbon (see allotropy), the hardest natural substance known, used as a gem and in industry. Properties
..... Click the link for more information. .
Imperfectly crystallized diamond material unsuitable for gems because of its shape, size, or color and because of flaws or inclusions; used for abrasive and cutting purposes. Also spelled boart.