Hercynite
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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.<ref name=Handbook/>
It was first described in 1847 and its name originates from the Latin name for the Harz, Silva Hercynia, where the species was first found.<ref name=Handbook/><ref name=Webmin/>
Hercynite is a spinel of regular symmetry and normal cation distribution, but some disorder occurs in its structure. It consists of ferrous (Fe2+) ions and aluminium ions (Al3+); however some ferric ions (Fe3+) may be located in the structure of hercynite.<ref>Template:Cite journal</ref>
Melting point of this mineral is inbetween Template:Convert.<ref>Template:Cite journal</ref>