Facts & News 🧠 on Instagram: "Follow (us) @FCTS to learn something new everyday 🧠 This spark like flash can look as if heat alone is igniting the flint but the effect is actually mechanical in origin. Flint is extremely hard and brittle so when it makes contact with a hot metal surface it can shave off microscopic metal fragments from the stove or from trace impurities. Once separated those tiny metal particles are suddenly exposed to oxygen while already warm which allows them to oxidize almo