Flint is a common ore that you can use to start a fire by placing it next to wood and hitting it with a metal weapon.

Best Sources of Flint

You will sometimes find large amounts of Luminous Stone Deposits clustered together. They can be found in caves, such as the Royal Hidden Passage, Corta Lake Cave, Rodai Lakefront Tunnel, and Calora Lake Cave. These large clusters of Luminous Stone Deposits have a fair chance of dropping flint.

Flint can also be found near most stables.

Regular Ore Deposits have the best chance of dropping Flint, but the chance is somewhat low.

Stone Tali of all types have a chance of dropping Flint, with Igneo Talus having the best chance of dropping Flint.

You can also purchase Flint for 10 rupees each from Shmid at the YunoboCo HQ Mineral Market, next to the road that goes south from Goron City. To restock his store, go some place far away and sleep or sit by a fire until morning.