Hematite (Oxide)
Fe2O3Hardness: 5.5 - 6.5
Specific Gravity: 4.9 - 5.3
Characteristics: Red, brown, or black; Metallic to earthy luster; slowly dissolves in HCl; may be iridescent; subconchoidal fracture; aggregates may be massive, in rosettes, botryoidal, reniform, micaceous and foliated, or earthy.
Found in some sandstones; banded iron formations; granitic intrusives; felsic volcanics; various metamorphic rocks; common in at least trace amounts in many other lithologies.
Hematite accounts for aproximately 90% of all the iron mined in the US. It is the primary ore of iron.
(Primary text: Perkins, D. 2002. Mineralogy. Prentice Hall.)