Spessartine
Spessartine is the manganese aluminum member of the garnet group, prized for its bright orange to reddish-orange color. It forms well-shaped dodecahedral or trapezohedral crystals, often in pegmatites or on smoky quartz, and the most vivid stones are cut as gems.
Spessartine properties at a glance
| Type | Silicate Minerals |
|---|---|
| Chemical formula | Mn3Al2(SiO4)3 |
| Mohs hardness | 7 |
| Crystal system | cubic |
| Luster | vitreous |
| Streak | White |
| Cleavage | None |
| Fracture | Conchoidal to uneven |
| Specific gravity | 4.19 |
| Transparency | transparent |
| Common colors | Orange, Red, Brownish red, Yellowish orange |
| Rarity | uncommon |
Geology & background
Spessartine is the manganese-rich garnet end member, crystallizing in granite pegmatites, in skarns, and in some manganese-rich metamorphic rocks and rhyolites.
Recognized as a distinct garnet species in the 19th century, spessartine remained a collector curiosity until major finds in Namibia and Nigeria in the 1990s brought orange garnet into wider use as a gemstone.
How to identify Spessartine
- Look for bright orange to reddish-orange isometric crystals with dodecahedral or trapezohedral faces and no cleavage.
- High hardness near 7 and high density help separate spessartine from softer orange minerals.
- Composition often lies between spessartine and almandine, so confirm gem-grade stones with proper testing.
Where Spessartine is found
Spessartine occurs in granite pegmatites and metamorphic rocks, with notable specimen and gem localities in the United States, Brazil, Namibia, Nigeria, China, and Madagascar.
How much is Spessartine worth?
| Entry-level specimen | $15 |
|---|---|
| Typical collector specimen | $120 |
| Premium specimen | $900+ |
Value depends on color saturation, transparency, crystal form, size, locality, and whether material is gem grade.
Common uses
- Faceted gemstones
- Jewelry
- Collector specimens
- Mineralogical reference material
Interesting facts
- Spessartine is named for the Spessart district in Bavaria, Germany, where it was first described.
- Vivid orange gem material is marketed as mandarin garnet.
- It forms a continuous chemical series with the iron garnet almandine, so many stones are intermediate in composition.
- Bright spessartine crystals perched on smoky quartz are among the most sought-after pegmatite specimens.
Care & safety
Spessartine is hard and durable but brittle, so it can chip or fracture on sharp impact.
Avoid inhaling dust. Do not cut, grind, or polish unknown specimens without eye protection and a proper respirator.
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