Crystal

Easton's Bible Dictionary

(Ezek 1:22, with the epithet “terrible,” as dazzling the spectators with its brightness). The word occurs in Rev 4:6; 21:11; 22:1. It is a stone of the flint order, the most refined kind of quartz. The Greek word here used means also literally “ice.” The ancients regarded the crystal as only pure water congealed into extreme hardness by great length of time.

International Standard Bible Encyclopedia

kris'-tal: In English Versions of the Bible the word is probably intended to signify rock-crystal, crystallized quartz. This the Greeks called krustallos, "ice," believing it to have been formed from water by intense cold. Thus in Rev 4:6; Rev 21:11; Rev 22:1, either "crystal" (EV) or "ice" (Greek, krustallos) suits the context. The word rendered "crystal" in Ezek 1:22 (qerach) is ambiguous in precisely the same way (the Revised Version, margin "ice"). In Job 28:17 the context favors the King James Version "crystal," rather than the Revised Version (British and American) "glass" (zekhukhith). Finally, in Job 28:18 the Revised Version (British and American) reads "crystal" for the King James Version "pearls" (Hebrew gabhish; the weight of evidence favors the Revised Version (British and American) in spite of the parallelism suggested by the King James Version).