Muirite
Muirite is an IMA-recognized mineral species in the silicate class, with the chemical formula Ba₁₀Ca₂Mn²⁺TiSi₁₀O₃₀(OH,Cl,F)₁₀.
It crystallizes in the tetragonal crystal system (space group P4/mmm).
Key properties: Mohs hardness 2.5; specific gravity 3.86; Pale orange streak; Subvitreous luster; optically uniaxial.
IMA symbol Mui, IMA status: approved, named in 1964.
Found in sanbornite-quartz-bearing metamorphic rock (Fresno Co., California, USA).
It is found associated with Sanbornite, verplanckite (Fresno Co., California, USA); gillespite, sanbornite, taramellite, fresnoite, pellyite, barite (Itsy Mountains, Yukon, Canada).
The name refers to John Muir (1834–1914), American mountaineer, conservationist, and naturalist, whose name is intimately associated with the California Sierra Nevada.