Hercynite
Hercynite is an oxide mineral recognized for its hardness and durability, with notable Chinese occurrences.
About Hercyniteextended article
Hercynite is the iron-bearing end-member of the spinel group, an iron aluminium oxide (FeAl2O4). It is the dark counterpart of gem spinel: typically black to very dark green or brown, opaque, and rarely of facet quality. Its name comes from the Hercynian Forest of central Europe.
Properties
Like other spinels it is isometric and hard (7.5–8), often forming octahedral crystals or granular masses, and it can be weakly magnetic where it grades toward magnetite. It frequently forms in solid solution with other spinel-group oxides.
Occurrence
Hercynite forms in high-temperature, aluminium-rich metamorphic rocks (emery deposits, granulites) and in some mafic igneous rocks. It is a member of the wider spinel group of oxides.
About Hercynite
Hercynite is an oxide mineral in the spinel group and has the chemical formula FeAl₂O₄. It crystallizes in the cubic system and ranks among the harder species, with lasting durability.
Identification & care
Hercynite typically forms octahedral crystals, massive, granular. Its color is typically dark green to black and brownish-black. The luster is vitreous, the streak is grayish-green, and specimens range from translucent to opaque. The cleavage is imperfect on {110}. The fracture is conchoidal, which aids identification.
Collector context
Collector notes
For collectors, Hercynite is a benchmark crystalline species. Documented Chinese occurrences are recorded at Dachang ore field, among others.
Frequently asked questions
What is Hercynite?
Hercynite is an oxide mineral recognized for its hardness and durability, with notable Chinese occurrences.
What crystal system does Hercynite belong to?
Hercynite crystallises in the Isometric crystal system.
References & databases
Mindat.org is the world’s largest open mineralogy database. Our descriptions are written independently and fact-checked.