Native iron is a rarity on our planet due to the oxygen-rich atmosphere. The oxygen in the air quickly oxidizes iron in metallic form to iron oxides. Only a few locations worldwide have the physico-chemical properties to produce iron. To do this, a basalt vein, which is rich in iron-containing minerals, must pass through a coal seam on its way to the earth's surface. The reducing conditions enable the formation of iron. Meteorites made of iron and nickel are also a source of collector's items.