Description: Hematite occurs in a range of forms, and its color ranges from black to gray, or from red to brown depending on which variety is present. Regardless of appearance, all varieties of hematite produce a distinctive reddish-brown streak that serves to distinguish it from most common minerals.
Hematite is the most abundant and economically important source of iron in our world. Hematite is also prized for its red color: from lipstick to fire trucks and rusted scrap iron, most red pigments in our world and society are derived from hematite. Hematite stains many soils red, and the Martian landscape (minerals out of this world :).
Chemical Formula: Fe2O3
Crystal Form: Crystals generally thick to thin tabular, rarely prismatic or scalenohedral; also rarely rhombohedral , producing pseudo-cubic crystals. Commonly not crystalline, but rather in sub-parallel growths or as rosettes ("iron roses.") Sometimes in micaceous to platy masses. May be compact columnar or fibrous masses, sometimes radiating, or in reniform botyroidal masses with a smooth fracture ("kidney ore"), and stalactic. Frequently in earthy masses, also granular, friable to compact, concretionary and oolitic.
Crystal System: Trigonal
Color: Steel-grey to black in crystals and massively crystalline ores, dull to bright "rust-red" in earthy, compact, fine-grained material.
Streak: Reddish brown ("rust-red")
Luster: Metallic, Sub-Metallic, Dull, Earthy
Fracture: Irregular/Uneven, Sub-Conchoidal
Cleavage: None
Hardness: 5 to 6 on Moh’s scale
Density/Specific Gravity: 5.26 g/cm3 !!
Magnetism: N/A
Taste: N/A
Hydrochloric acid: N/A
Radioactivity: N/A
Fluorescence: N/A
Distinguishing Physical Properties:
Streak: Red-Brown,
Specific gravity: dense, heft
Photograph Attribution: Hematite specimen photograph by Sean C. Murphy, 2020.