Spessartite (Spessartite Garnet)
Spessartite (spessartite garnet) is an orange to reddish-orange garnet rich in manganese. Its name is derived from the Spessart region of Germany, a classic locality. It forms solid solutions with other members of the garnet group, such as almandine, pyrope, and grossular, resulting in a continuous variation in composition and hue.
Spessartite with a beautiful, vivid mandarin orange color
Basic Information
| English Name | Spessartite / Spessartine Garnet |
|---|---|
| Japanese Name | Manban-zakuroishi (Manganese Aluminum Garnet) |
| Chemical Formula | Mn₃Al₂[SiO₄]₃ |
| Crystal System | Isometric |
| Hardness | 7–7.5 |
| Specific Gravity | Approx. 4.03 |
Characteristics, Localities, and Varieties
Stones from the Little Three Mine in California are relatively pure in manganese, displaying a vivid orange color, and are sold under the trade name "Mandarin Garnet."
In Japan, the Wada Pass in Nagano Prefecture is a known locality. These stones tend to have a darker color due to solid solution with almandine and are said to be slightly more brittle than almandine.
Additionally, mixed crystals with pyrope can lead to "color-change garnets" (alexandrite-type), which appear to change color depending on the light source; these are frequently reported in stones from Sri Lanka.
Identification, Treatments, and Similar Stones
Another garnet in the orange-to-golden color range is the grossular variety "golden garnet" (such as hessonite). When compared, spessartite features a higher refractive index and stronger brilliance.
Because it contains Mn, it shows a weak reaction to magnets, which serves as an identification tip. In contrast, grossular-type hessonite has almost no magnetism and often displays an internal structure that looks like molasses.
Stones with significant cracks may undergo resin impregnation to make the flaws less visible. Red-toned spessartite can look similar to zircon, while strongly orange ones can resemble hessonite garnet; however, no synthetic spessartite is currently known, and it is believed that only natural stones are on the market.
Handling Tips: Durability can vary depending on whether the stone has been impregnation-treated. When purchasing expensive loose stones or jewelry, it is recommended to confirm the treatment information for peace of mind. Understanding the differences from other orange garnets will also increase your satisfaction as a collector.