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Foitite

Year of discovery: 1993 (California, USA), 1994 (Japan)

Locality list: 7 localities of foitite

• Fe₂AlAl₆Si₆O₁₈(BO₃)₃(OH)₄
• ([],Na)(Fe,Al)₃Al₆Si₆O₁₈(BO₃)₃(OH)₄
• [][Fe²⁺₂][Al³⁺][Al³⁺₆][(OH)₃|OH|(BO₃)₃|(SiO₃)₆]^25-

• Class: Vacant-subgroup 1 < X-vacant-tourmaline group < Tourmaline supergroup
• Class: Cyclosilicate (Single ring) - Borate - Hydroxide
• Electrical: Piezoelectric, Pyroelectric

• []Al => NaFe: Schorl

• Fe => Mg: Magnesiofoitite

• Fe(OH) => AlO: Oxy-foitite

• Fe₂ => LiAl: Rossmanite

• Color: Dark bluish gray, Bluish black
• Streak: Grayish white
• Luster: Vitreous
• Diaphaneity: Transparent-Translucent

• Cleavage: No
• Hardness: 7
• Density: 3.2

• System: Trigonal
• Group: 3m, R3m
• Lattice: a=16.0, c=7.1