spessartine

Spessartine, also spelled spessartite, is a manganese aluminum garnet with the chemical formula Mn3Al2Si3O12. It is a member of the garnet group and crystallizes in the isometric (cubic) system. Spessartine commonly forms well-shaped crystals, often dodecahedra or trapezohedra, and ranges from transparent to translucent.

The mineral takes its name from the Spessart region of Germany, where it was first described. Its characteristic orange to reddish-orange color is the most diagnostic feature, though it can appear pinkish or brownish in some specimens. Like other garnets, spessartine is hard and durable, with a Mohs hardness around 6.5–7.5 and a relatively high specific gravity (approximately 3.9–4.3). It is typically non-pleochroic and shows a strong, high-refractive luster in well-formed crystals.

Spessartine forms in Mn-rich metamorphic rocks and in pegmatites associated with granitic intrusions. It occurs with quartz, mica, tourmaline, and other garnet varieties such as almandine and pyrope. Notable sources include the Spessart region in Germany (the origin of the name), as well as deposits in Namibia, Brazil, Madagascar, Sri Lanka, and the United States.

In the gem trade, spessartine is valued for its vivid orange to orange-red colors. It is used as a gemstone in jewelry, frequently cut as faceted stones or cabochons. Color can sometimes be enhanced by heat treatment; irradiation or other treatments may also be used in some cases, with disclosure customary in reputable sales.