Mineral description : Gahnite

Dark blue gahnite in an anthophyllite - mica matrix. From Näverbergsgruvan, Falun.

Mineral class	Oxides : Corundum - Spinell - Chrysoberyll group
Chemical formula	ZnAl2O4
Crystal system	Cubic
Habitus	Crystals octaedric, sometimes as cubes or dodecahedrons. Twinning according to the spinel twin law could create pseudo trigonal crystals. Common as massive or grains.
Cleavage	None, fracture conchoidal.
Hardness	7.5-8
Density	4.55-4.60
Color	Dark gray, dark blue, green, brown, yellow.
Streak	Gray
Luster	Vitreous, translucent to opaque.
Description	A rare spinell mineral.
Occurance
Associates	Calcite, garnets, anthophyllite.
Notes	Type locality : Falun, Sweden.
Locations	A rare mineral with several good crystal localities in Sweden. Falu mine, Dalarna. As ark gray octaedric crystals up to a couple of cm in size. Näverbergsgruvan, Falun, Dalarna. As blue green rounded grains with anthophyllite. Östra Silfberg, Ludvika, Dalarna. Garpenbergsgruvan, Dalarna. Kobergsgruvan, Persberg, Värmland. Kaveltorpsgruvan, Ljusnarsberg.

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