The Hebrew {kerach,} which generally denotes ice, doubtless here signifies crystal, ([krystallos,] from [kryos,] cold, ice, and [stellomai,] to concrete,) as it is rendered by the LXX. and Vulgate. It is a very large class of silicious minerals, hard, pellucid, naturally colourless, of regularly angular figures, and of simple plates; not flexible, nor elastic, but giving fire with steel; not fermenting by acid menstrua, but calcinable in a strong fire. There are three orders of pure crystal: the first is perfect columnar crystals, with double pyramids, of eighteen planes, in an hexangular pyramid at each end; the second is that of perfect crystals, without a column, of twelve or sixteen planes, in two hexangular pyramids: and the third is that of imperfect crystals, with single pyramids, of ten or twelve planes, in an hexangular or pentangular column. Terrible crystal seems to denote that which was well cut and polished, vividly refracting the rays of light.