Spessartine

spessartine

rhodonite

tephroite

pyroxmangite

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Formula: Mn2+3Al2(SiO4)3
Nesosilicate (insular SiO4 groups), garnet group, forms a series with almandine, manganese-bearing mineral
Crystal System: Isometric
Specific gravity: 4.12 to 4.32 measured, 4.19 calculated
Hardness: 7
Streak: White
Colour: Pink, orange, light brown to dark brown
Solubility: Insoluble in hydrochloric, sulphuric and nitric acid
Common impurities: Ti,Fe,Mg,Ca,H2O,Y
Environments:

Plutonic igneous environments
Volcanic igneous environments
Pegmatites
Metamorphic environments

Spessartine occurs in plutonic igneous rocks and pegmatites and in skarn. In skarn and maganese-rich assemblages of metasomatic origin it is associated with rhodonite, tephroite, pyroxmangite and other manganese minerals. In granite pegmatites the garnet is usually an almandine-spessartine solid solution (Lauf p135).

At Broken Hill, New South Wales, Australia, spessartine is associated with galena (Lauf p136).

At Tongbei, Fujian province, China, spessartine occurs with smoky quartz and feldspar (Lauf p135).

At Ruby mountain, Chaffee county, Colorado, USA, small spessartine crystals are found in rhyolite (Lauf p135).

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