Idocrase derives its name from Greek words “eidos”, meaning likeness and “krasis”, meaning composition. Collectively meaning “mixed form”, this is an allusion to its crystals showing a mixture of other minerals.

Idocrase is a fascinating gem originally discovered at the volcano, Mount Vesuvius. Not surprisingly, one of its other names is Vesuvianite.

Idocrase is both a rare and beautiful gem and extremely popular among gemstone collectors.



Idocrase’s color is normally green, but also can be brown, yellow, blue or purple. Idocrase forms as a result of contact between metamorphic rock and impure limestone, and is usually found with other exotic minerals. Due to variations in its composition, a range of physical properties occurs. Idocrase’s crystals are typically thick and stubby and striated along their length.

A massive green translucent gem variety of Idocrase is called Californite, after the location of its initial discovery. Often confused with Jade, this variety of Idocrase is sometimes incorrectly called Californian Jade or Vesuvian Jade. However, upon closer inspection, its crystal shape reveals its true identity.

Another popular variety of Idocrase is Cyprine. Sky blue in color, Cyprine is mostly found in Norway.

Transparent Idocrase suitable for jewelry is typically faceted using table or step cuts. However, gem quality crystals of Idocrase are incredibly scarce, making this gemstone highly collectable.