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Formula: BaSi2O5
Phyllosilicate (sheet silicate), barium-bearing mineral
Crystal System: Orthorhombic
Specific gravity: 3.70 measured, 3.77 calculated
Hardness: 5
Streak: White
Colour: Colourless to white
Solubility: Decomposed by acids
Common impurities: Al,Fe,Mg,Ca,Sr,H2O
Environments
Sanbornite is a major component of barium-silicate assemblages at or near the fringes of large
granite intrusives (Webmin), associated with witherite
and taramellite
(Dana).
Localities
At the Gun claim, Wilson Lake, Itsi Mountain, Watson Lake mining district, Yukon, Canada, sanbornite is associated with
gillespite, pellyite,
taramellite, fresnoite,
muirite and baryte
(HOM).
At the type locality, the Trumbull Peak barium-silicate deposit, Trumbull Peak, Clearing House, Clearing
House Mining District, East Belt, Mariposa county, California, USA, sanbornite occurs in veins in metamorphosed sediments, largely
quartzite and hornfels. Associated minerals include
quartz, gillespite,
diopside, schorl,
celsian, pyrrhotite and
witherite
(HOM).
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