FLINT, an opaque black, gray, brownish-black or smoky brown variety of very fine grained silica (silicon dioxide) possibly with some hydrated silica. Flint, which is allied to chalcedony (q.v.) is not as hard as many gem stones (Ezek 3:9), but is harder than steel and is used as an abrasive. It commonly occurs as hard, tough, structureless nodules (cf. Isa 50:7), particularly in chalk deposits which, to a large extent, consist of calcareous remains of minute organisms together with varying proportions of detrital sandy (siliceous) and clayey material. The concretionary nodules of flint represent the redeposition, from percolating ground water, of silica derived from the solution of small scattered sponge spicules, originally scattered through the chalkstone (q.v.). The nodules tend to be found mainly along bedding planes in the chalk where there was some detrital silica. This is the case for the flint nodules occurring in the chalks and chalky limestones of northern Samaria, parts of western Galilee and over large areas of Jordan E of the Jordan Rift Valley. In Jordan, particularly, the relatively soft chalkstone has been eroded away, mainly by the wind, and has left the hard impervious nodules as residual flint gravels.

Flint fractures into shell-like shapes as the result of either a blow or under thermal action (heat or frost). The flakes, which at their edges may be pale gray or yellowish-brown, afford sharp cutting edges. Because of this, and the hardness of the material, flint was extensively used by prehistoric man for weapons and tools.

Bibliography E. S. Dana, A Textbook of Mineralogy, 4th ed. (revised by W. E. Ford) (1932), 472, 473; E. M. Blaiklock (ed.), The Zondervan Pictorial Bible Atlas (1969), 438-452.