Långbanite
Långbanite is an IMA-recognized mineral species in the silicate class, with the chemical formula Mn²⁺₄Mn³⁺₉Sb⁵⁺O₁₆(SiO₄)₂.
It crystallizes in the hexagonal crystal system (space group P31m).
Key properties: Mohs hardness 6.5; specific gravity 4.92–4.94; Dark reddish brown streak; Metallic, brilliant luster; optically uniaxial.
IMA symbol Lgb, IMA status: approved, named in 1888.
Found in crystalline limestones and manganese-rich skarns in metamorphosed manganese deposits.
It is found associated with Manganoan aegirine, richterite, braunite, magnetite, hausmannite, rhodonite, hedyphane.
The name refers to the place of its original discovery, Lº angban, Sweden.
Index entry. This entry combines official IMA/RRUFF species data with published physical-property data — a full written entry hasn’t been published yet.
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