EntityQ377086· pop 14· linked from 15 articles

hercynite

Hercynite is a spinel mineral with the formula FeAl2O4.

Key facts

Mineral.name: Hercynite
Mineral.category: Oxide minerals Spinel group Spinel structural group
Mineral.image: Hercynite.jpg
Mineral.imagesize: 260px
Mineral.formula: Fe2+Al2O4
Mineral.IMAsymbol: Hc
Mineral.molweight: 173.81 g/mol
Mineral.strunz: 4.BB.05
Mineral.system: Isometric
Mineral.class: Hexoctahedral (mm) H-M symbol: (4/m 2/m)
Mineral.symmetry: Fdm (no. 227)
Mineral.color: Black
Mineral.habit: Euhedral crystals. Also massive to granular
Mineral.cleavage: [111] indistinct
Mineral.fracture: Uneven – flat surfaces (not cleavage) fractured in an uneven pattern.
Mineral.mohs: 7.5
Mineral.luster: Vitreous (glassy)
Mineral.refractive: n = 1.8

via Wikipedia infobox

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Hercynite is a spinel mineral with the formula FeAl2O4.

It occurs in high-grade metamorphosed iron-rich argillaceous (clay-containing) sediments as well as in mafic and ultramafic igneous rocks. Due to its hardness it also is found in placers.