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Barroisite [abbr. Brs, Bar ]

Year of discovery: 1922 (Cleary creek, USA), 1960 (Japan)

Locality list: 42 localities of barroisite

• []NaCaMg₃Al₃Si₇O₂₂(OH)₂
• []NaCa(Mg,Fe²⁺)₃(Al, Fe³⁺)₂AlSi₇O₂₂(OH)₂
• [][Na⁺Ca²⁺][Mg²⁺₃Al³⁺₂][(OH)₂|AlSi₇O₂₂]^15-

• Class: Na-Ca amphibole subgroup < w(OH,F,Cl)-dominant amphibole group < Amphibole supergroup
• Class: Ino-Aluminoslicate (Double chain) - Hydroxide

• Mg => Fe²⁺: Ferro-barroisite (Series)

• Al => Fe³⁺: Ferri-barroisite

• NaAl => CaMg: Magnesio-hornblende

• NaSi => CaAl: Tschermakite

• Al₂ => MgSi: Winchite

• []Si => NaAl: Taramite

• Color: Bluish green-Green
• Streak: White
• Luster: Vitreous
• Diaphaneity: Translucent

• Habit: Prismatic

• Cleavage: Perfect (2 planes, 120 degree)
• Hardness: 5-6
• Density: 3.0

• System: Monoclinic
• Group: 2/m, C2/m
• Lattice: a=9.8, b=17.9, c=5.3, β=104.5