An extremely hard stone, harder than steel, so hard that when two pieces are struck together a fire can be started from the spark. The Bible makes reference to flint when, in figures of speech, it emphasizes such qualities as hardness, durability, and resistance to opposition.​—Isa 5:28; 50:7; Eze 3:9.

Flint is found in limestone and chalk deposits in Israel and in the northern Sinai Peninsula. It is quite brittle and fractures with a glossy surface. Its chips have very sharp edges, a characteristic that man was quick to recognize and put to use. From very early times knives, axheads, chisels, spearheads, arrowheads, and other tools and weapons have been fashioned out of this rock. It was with a flint that the wife of Moses circumcised her son; when the nation of Israel reached Gilgal similar surgery was successfully performed by the use of knives made of flint. (Ex 4:25; Jos 4:19; 5:2, 3, 8, 9) Jehovah brought water out of flinty rock for his people in the wilderness.​—De 8:15; Ps 114:8.