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Pharmacosiderite

Year of discovery: 1813 (Tincroft mine, UK, and Carharrack mine, UK), 1897 (Japan)

Locality list: 29 localities of pharmacosiderite

• KFe₄(AsO₄)₃(OH)₄,6-7H₂O
• [K⁺][Fe³⁺₄][(OH)₄|(AsO₄)₃]^13-,6-7H₂O

• Class: Pharmacosiderite group
• Class: Arsenate - Hydroxide - Hydrate
• Soluble in: HCl, NH₃aq (turn red)
• Electrical: Piezoelectric (Weak), Pyroelectric (Weak)
• Radioactive: Very weak
• Alter to Limonite and Wad.
• Substitution pseudomorph: Replace Siderite.

• K => Na: Natropharmacosiderite
• K => H₃O: Hydroniumharmacosiderite
• K => Ba_0.5: Bariopharmacosiderite

• Color: Green, Yellowish green, Brown
• Tarnish: Red (by NH₃aq)
• Streak: Yellowish green
• Luster: Adamantine
• Diaphaneity: Transparent-Translucent

• Habit: Cubic, Hexagonal prism
• Aggregate: Radial

• Cleavage: Imperfect on {001} (3 planes)
• Hardness: 2.5
• Density: 2.8

• System: Cubic
• Group: (-4)3m, I(-4)3m
• Lattice: a=8.0