Gahnite

oxide

hercynite

Formula: ZnAl2O4 multiple oxide, spinel group, gahnite-hercynite series, gahnite-spinel series.
Specific gravity: 4.57
Hardness: 7½ to 8
Streak: Grey
Colour: Dark blue-green, yellow, brown, black
Solubility:
Environments:

Pegmatites
Metamorphic environments

Gahnite occurs in crystalline schist, in granite pegmatites especially those rich in lithium, and in contact metamorphosed limestone. It also occurs in high temperature replacement ore deposits in schist or marble (Dana).

Common impurities: Fe,Mg

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