Vesuvianite
Vesuvianite, also called idocrase, is a calcium aluminum silicate that typically forms prismatic crystals or massive aggregates. Usually green to brown, it is a characteristic skarn mineral and an occasional gemstone for collectors.
Vesuvianite properties at a glance
| Type | Silicate Minerals |
|---|---|
| Chemical formula | Ca10(Mg,Fe)2Al4(SiO4)5(Si2O7)2(OH)4 |
| Mohs hardness | 6.5 |
| Crystal system | tetragonal |
| Luster | vitreous |
| Streak | White |
| Cleavage | Poor |
| Fracture | Uneven |
| Specific gravity | 3.4 |
| Transparency | translucent |
| Common colors | Green, Brown, Yellow, Blue |
| Rarity | uncommon |
Geology & background
Vesuvianite forms by contact metamorphism of impure limestones, crystallizing in skarns and metamorphosed carbonate rocks where calcium, aluminum, and silica recombine.
Vesuvianite was described and named in 1795 from specimens collected on Mount Vesuvius. It became a classic mineralogical species and a model mineral for studying complex calcium silicates.
How to identify Vesuvianite
- Look for stout prismatic tetragonal crystals or massive aggregates with a vitreous luster.
- Green to brown color and occurrence in skarns help distinguish vesuvianite from garnet.
- Hardness near 6.5 and poor cleavage support identification.
Where Vesuvianite is found
Vesuvianite occurs in skarns and metamorphosed limestones worldwide, with the type locality on Mount Vesuvius in Italy and additional fine specimens from the United States, Canada, Russia, Norway, and Kenya.
How much is Vesuvianite worth?
| Entry-level specimen | $10 |
|---|---|
| Typical collector specimen | $55 |
| Premium specimen | $350+ |
Value depends on crystal size, color, transparency, locality, damage, and overall aesthetics.
Common uses
- Collector specimens
- Faceted and cabochon gemstones
- Ornamental californite stone
- Educational mineralogy
Interesting facts
- Vesuvianite was first found among the ejected blocks of Mount Vesuvius, giving the mineral its name.
- The alternate name idocrase comes from Greek words meaning mixed form, reflecting its varied crystal faces.
- A massive green variety called californite resembles jade and is cut as an ornamental stone.
- Rare blue cyprine vesuvianite owes its color to traces of copper.
Care & safety
Vesuvianite is fairly hard and durable, though crystals can still chip from sharp impacts.
Avoid inhaling dust. Do not cut, grind, or polish unknown specimens without eye protection and a proper respirator.
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