Iron Oxide

Iron oxide, hematite, also called oligist, is a mineral widespread on the surface of the Earth and its identification is easy. It has a black metallic luster with characteristic red reflections and, above all, when it is streaked with a lime, it gives a red powder which allows it to be unambiguously distinguished from other minerals resembling it.

Its crystals are stocky and most often flattened, or lamellar and tangled, sometimes arranging like the petals of a rose, hence the name "iron rose" (or "micaceous hematite"), by analogy with the appearance of the "sand rose" of gypsum.

Hematite also appears in concreted masses: either pisolitic, oolithic, fibrous or kidney-shaped in earthy or red and loose clayey gangues - it gives red ocher -; or in nipple kidneys more shapeless than those of marcasite which, themselves, are most often spherical.