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Pumpellyite-(Mg)

Year of discovery: 1925 (Keweenaw Co., USA), 1977 (Japan)

Locality list: 11 localities of pumpellyite-(Mg)

• Ca₂MgAl₂Si₃O₁₁(OH)₂,H₂O
• Ca₂(Mg,Fe,Al,Mn)Al₂Si₃O₁₁(OH)₂,H₂O
• [Ca²⁺₂][Mg²⁺][Al³⁺₂][(OH)₂|SiO₄|Si₂O₇]^13-,H₂O

• Class: Pumpellyite series - Pumpellyite group
• Class: Sorosilicate - Nesosilicate - Hydroxide - Hydrate

• Mg => Fe: Pumpellyite-(Fe2+) (Series)
• Mg => Mn: Pumpellyite-(Mn2+)

• Mg(OH) => AlO: Pumpellyite-(Al)
• Mg(OH) => FeO: Pumpellyite-(Fe3+)

• Al => Cr: Shuiskite

• MgAl₂ => Fe₃: Julgoldite-(Fe2+) (Series)

• Color: Green, Blue, Greenish black, Brown
• Streak: White
• Luster: Vitreous
• Diaphaneity: Translucent

• Habit: Acicular
• Aggregate: Loose radial

• Cleavage: Good on {001} and {100} (2 planes)
• Hardness: 5.5
• Density: 3.2

• System: Monoclinic
• Group: 2/m, A2/m
• Lattice: a=8.8, b=5.9, c=19.1, β=97.4

Etymology: Raphael Pumpelly (1837-1923), American geologist