Spessartine Garnet
(c) 2005 Andrew Alden, licensed to About.com, Inc. (fair use policy)
Spessartine is one of the aluminum garnets, along with almandine and pyrope forming the "pyralspite" group. (The calcium or "ugrandite" garnets consist of uvarovite, grossular and andradite.) Its ideal composition is Mn3Al2(SiO4)3, with the silica groups (SiO4) being isolated, not linked in chains or sheets as in most silicate minerals. Almandine and pyrope have iron (Fe) and magnesium (Mg), respectively, instead of the manganese (Mn).
Spessartine is an uncommon garnet. It ranges in color from red-brown to yellow-brown. Its orange occurrence is a gemstone known as mandarin garnet.
This spessartine specimen is from the Tongbei area in Fujian province, China. The matrix material appears to be fine-grained quartz. The field of view is about 2 centimeters.
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