a. Cryst. [f. as prec. + -AN. Cf. mod.F. trapézien (Littré).] Having trapeziform lateral faces in two rows between the two bases, as a crystal of barium sulphate.
1757. trans. Henckel’s Pyritol., 23. Prismatical, trapezian, or inegular.
1805–17. R. Jameson, Char. Min., 203. A crystal is said to be … Trapezian, when its lateral surfaces consist of trapezia, which lie in two rows, between two bases, as in trapezian heavy-spar…. It is a rectangular four-sided table, bevelled on the extremities, where the bevelling planes are trapeziums.
1828. in Webster. Hence in later Dicts.
