WGNHS
Wisconsin Geological and Natural History Survey

Spessartine

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Spessartine crystal from pegmatite dike. SEM photo. Waterloo Quarry, Dodge County, Wisconsin. (Tom Buchholz sample and image.)

Formula: Mn3Al2(SiO4)3 Isometric

Description:Spessartine is a member of the garnet family. It is usually red to orange in color and is found generally in granite pegmatites, where it can form large gemmy crystals. It is also found in metamorphic rocks formed from manganese-rich protoliths.

DODGE COUNTY: Small crystals of spessartine occur in pegmatite dikes cutting quartzite in the Michels Materials corporation Quarry near Waterloo. (Tom Buchholz, personal communication.)

FLORENCE COUNTY: Subhedral red crystals of spessartine occur as grains up to 1.4 cm in diameter in a zoned pegmatite in the NE NE sec. 22 T.39N. R.17E. Associated minerals are albite var. cleavelandite, quartz, microcline, and polylithionite (formerly called zinnwaldite) (Koehler, 1989, pers comm.).

RUSK COUNTY: Spessartine occurs as small dodecahedral porphyroblasts in chlorite schist at the Flambeau Mine, Sec. 9 T.34N. R.6W. (May, 1977).