Spessartine Garnet

Spessartine is the manganese-aluminum garnet, named after the Spessart Mountains in Germany where it was first identified. The pure end-member is colored vivid orange by manganese. Most natural spessartine contains some almandine (iron) component, which shifts the color toward reddish tones.

It forms in granitic pegmatites, some metamorphic rocks, and rarely in rhyolites. The finest gem-quality material comes from pegmatites where manganese-rich fluids created pockets of clean, intensely colored crystals. The Nigerian and Namibian sources that produce the most vivid 'mandarin garnet' quality stones formed in such environments.

In the late 1990s, electric-orange spessartine from Namibia hit the market and was branded 'mandarin garnet.' The trade name stuck, and vivid orange spessartine is now among the most sought-after colored garnets. Nigerian production from around 2000 onward increased supply of this electric orange material significantly.

Spessartine is identified by its vivid orange color, isometric crystal system (forming dodecahedra and trapezohedra), and relatively high specific gravity (4.18) for a garnet. It's singly refractive, which helps separate it from similarly colored doubly refractive gems.

Distinguish from hessonite garnet (grossular species, lower RI, different SG), fire opal (amorphous, lower SG, lower hardness), and citrine (hexagonal, much lower RI and SG). Spessartine's combination of vivid orange, high SG, and garnet crystal habit is distinctive.