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Gahnite [abbr. Ghn ]

Year of discovery: 1807 (Falun mine, Sweden), 1953 (Japan)

Locality list: 14 localities of gahnite

• ZnAl₂O₄
• [Zn²⁺][Al³⁺₂][O₄]^8-

• Class: Spinel subgroup < Oxyspinel group < Spinel supergroup
• Class: Oxide
• Insoluble in: HCl

• Zn => Mg: Spinel (Series)
• Zn => Mn: Galaxite
• Zn => Fe: Hercynite (Series)
• Zn => Be: Chrysoberyl

• Al => Mn: Hetaerolite
• Al => Cr: Zincochromite
• Al => Fe: Franklinite

• Color: Dark bluish green, Yellow, Black
• Streak: Gray
• Luster: Vitreous
• Diaphaneity: Opaque

• Habit: Octahedral

• Cleavage: Indistinct on {111} (4 planes)
• Hardness: 7.5-8
• Density: 4.3

• System: Cubic
• Group: m3m, Fd3m
• Lattice: a=8.1

• Coexist: Quartz (An exceptional example of Spinel group minerals)