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Groutite

Year of discovery: 1945 (Mahnomen pit, USA, and Sagamore Mangan no.2 pit, USA), 1959 (Japan)

Locality list: 8 localities of groutite

• MnO(OH)
• α-[Mn³⁺][OH|O]^3-

• Class: Diaspore group
• Class: Oxide - Hydroxide

• Polymorph: Feitknechtite (β, Trigonal), Manganite (γ, Monoclinic)

• Mn => Fe: Goethite (α), Akaganeite (β), Lepidocrocite (γ), Feroxyhyte (δ)
• Mn => Al: Diaspore (α), Böhmite (Bohmite) (γ)
• Mn => V: Montroseite
• Mn => Cr: Guyanaite, Bracewellite
• Mn => Ga: Tsumgallite
• Mn => Co: Heterogenite

• Color: Black, Bluish black
• Streak: Dark brown
• Luster: Metallic
• Diaphaneity: Opaque

• Cleavage: Perfect on {010} (1 plane), Distinct on {100} (1 plane)
• Hardness: 3.5-4
• Density: 4.1

• System: Orthorhombic
• Group: mmm, Pnma
• Lattice: a=4.6, b=10.7, c=2.9