hematite

{{Infobox mineral |boxtextcolor=#FFFFFF|boxbgcolor=#0e0d0b| name = Hematite | category = Oxide minerals | image = WLA hmns Hematite.jpg | imagesize = 260 | caption = Hematite crystals from Brazil | formula = iron(III) oxide, Fe2O3, α-Fe2O3 | IMAsymbol = Hem | strunz = 4.CB.05 | dana = 4.3.1.2 | symmetry = Rc (no. 167) | unit cell = a = 5.038(2) Å; c = 13.772(12) Å; Z = 6 | color = Metallic grey, dull to bright "rust-red" in earthy, compact, fine-grained material, steel-grey to black in crystals and massively crystalline ores | habit = Tabular to thick crystals; micaceous or platy, commonly in rosettes; radiating fibrous, reniform, botryoidal or stalactitic masses, columnar; earthy, granular, oolitic | system = Trigonal | class = Hexagonal scalenohedral (m) H–M symbol: ( 2/m) | twinning = Penetration and lamellar | cleavage = None, may show partings on {0001} and {101} | fracture = Uneven to subconchoidal | tenacity = Brittle | mohs = 5.5–6.5 | luster = Metallic to splendent | streak = Bright red to dark red | diaphaneity = Opaque | gravity = 5.26 | density = 5.26 - 5.3 | opticalprop = Uniaxial (−) | refractive = nω = 3.150–3.220, nε = 2.870–2.940 | birefringence = δ = 0.280 | pleochroism = O: brownish red; E: yellowish red | references = }}

Hematite (), also spelled as haematite, is a common iron oxide compound with the formula Fe2O3 and is widely found in rocks and soils. Hematite crystals belong to the rhombohedral lattice system which is designated the alpha polymorph of . It has the same crystal structure as corundum () and ilmenite (). With this crystal structure geometry it forms a complete solid solution at temperatures above .