Mineralpedia Details for Muirite

Named in honor of John Muir who was an American mountaineer, conservationist, and naturalist who was closely associated with the Sierra Nevada Mountains in California, USA from where Muirite gets its type locality. Muirite is a rare mineral found in only its type locality on Big Creek in California and from the Gun Claim in Yukon Territory, Canada. At the type locality it occurs “in Sanbornite-quartz-bearing metamorphic rock.”

Ref. Handbook of Mineralogy, Anthony et al (1995) and MSA at http://www.handbookofmineralogy.org/pdfs/muirite.pdf

Formula

Ba₁₀Ca₂Mn²⁺TiSi₁₀O₃₀(OH)₁₀ 

Crystal System

Tetragonal 

Crystal Habit

Anhedral Grains 

Cleavage

Indistinct, Indistinct, None 

Luster

Vitreous (Glassy) 

Color

orange, brown 

Streak

light orange 

Class

Tetragonal - Ditetragonal Dipyramidal 

Hardness

2.5 

WebMineral

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Mindat

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Large brownish orange grains to 5mm in bluish Sanbornite matrix associated with minor pale yellow Fresnoite.

Special Info

Type Locality

Tiny, about 1mm and less, orange crystal grains scattered in Sanbornite rich metamorphic rock. Muirite, named after John Muir, is found in only two localities worldwide according to Mindat.org. This interesting locality boasts 11 type locality minerals.

Rich specimen with dozens of equant orange crystal grains less than 0.5mm. It is associated with flashy crystal grains of Sanbornite and Pyrrhotite.