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Atomic Positional Parameters
Fe 12c 0.0000 0.0000 0.3553
O  18e 0.3059 0.0000 0.2500

Reference
RL Blake, RE Hessevick, T Zoltai and LW Finger (1966) American Mineralogist, 51, 123

Mineral Chemistry
Hematite has the corundum (Al₂O₃) structure with an approximately hexagonal close-packed array of oxygens. Fe³⁺ ions occupy two thirds of octahedral sites between oxygens; each FeO₆ octahedron shares a face with another in the layer above or below. Iron atoms lie on planes spaced approximately one third and two thirds the distance between oxygen layers.

The crystal structure of ilmenite (FeTiO₃) is closely related to that of hematite; in ilmenite, titaniums replace half the irons forming alternating iron (2⁺) and titanium (4⁺) layers between oxygen planes.

Hematite occurs in igneous, metamorphic and sedimentary rocks. Large iron ore bodies of hematite are found in regionally metamorphosed rocks of sedimentary origin.

In the CHIME figure, oxygens are represented by red spheres, irons by ochre spheres.