Despite being a common mineral, pyrite or "Fool's Gold" has a fascinating history. Fragile and poisonous when heated, it requires care in its use. It has traditionally been used in the manufacture of steel. The iron contained in it is extracted through carefully controlled heat treatment. The industry also obtains sulfuric acid from it, which it uses in oil refining, in fertilizers, paints and explosives. Pyrite is found in many parts of the world, especially where marble and slate are common. Easily combustible, true pyrite would have been used by the ancient Greeks to make fire. In the 16th century, when gunpowder was invented, it was an essential part of firearms. As it was fragile, it was replaced by flint, which is more reliable. By its shiny appearance, pyrite deceives novice miners, who mistake it for gold. Pyrite seems to be responsible for the old story that "the streets of London were paved with gold". This phenomenon occurs because the splashes of ferrous pyrite seen on the pavement shine like gold when illuminated by the sun. Likewise, the golden particles that glisten in the sparkling lapis lazuli gem are nothing more than pyrite. Nowadays it is also used to obtain sulfur and sulfuric acid, both with different industrial uses.