Hematite

Formula:  Fe2O3

Origin of name:  From Greek aima - blood

 

Crystal system:  Hexagonal

Crystal class:  -3 2/m

Twinning:  On {0001}, penetration; on {10-11}, lamellar

Unit cell: a = 5.04 Ǻ, c = 13.75 Ǻ

 

Colour:  Steel-gray to iron-black, thin fragments deep blood

Diaphaneity: 

Luster:  Metallic, submetallic, dull

Habit:  Crystals thin to thick tabular, rhombohedral, pyramidal, or prismatic; tabular crystals may form rosettes; massive

Hardness:  5 to 6

Specific gravity:  5.26

Cleavage:  2; {0001} and {10-11} parting due to twinning

Tenacity:  Subconchoidal to uneven; brittle

Streak:  Deep red or brownish red

 

Synonyms/varieties:  Martite (replacing magnetite), specularite (micaceous var.), turgite, oligiste iron, persian red

 

Comments:  Dimorphous with maghemite

 

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