Flint

Flint is a hard variety of chert (a form of quartz) found abundantly in the limestone regions of Palestine, the Sinai, and throughout the wilderness territories through which Israel traveled. Its extreme hardness and ability to hold a sharp edge made it the preeminent stone-tool material for cutting instruments before iron became widely available. Flint knives were used for circumcision in the wilderness period: Joshua circumcised the Israelites with "sharp flint knives" at Gilgal (Joshua 5:2-3).

Flint is used in two striking metaphorical expressions. In Isaiah 50:7 — part of the third Servant Song — the Servant declares: "I have set my face like flint, and I know I will not be put to shame" (Isaiah 50:7), describing unwavering determination in the face of suffering and opposition. Ezekiel 3:9 uses the same image when God strengthens the prophet: "Like the hardest stone, harder than flint, I have made your forehead" (Ezekiel 3:9). Both passages exploit flint's legendary hardness as a metaphor for resolute, divinely-given courage.