Idocrase (Vesuvianite)

Vesuvianite (also known as Idocrase) is situated in colors ranging from green to brown as well as a variety that is blue Cyprine. The complexities of its chemistry cause the number that is wide of and properties. The variety that is green similar in color to Peridot gems. Cyprine, the variety that is blue of, is colored by the addition of copper to its chemistry and it is also referred to as Cupreous Idocrase or Cupreous Vesuvianite.

There are numerous sources of Vesuvianite such as Asbestos, Quebec, Canada; California, Colorado and the brand new England region of USA; Mt. Vesuvius, Italy; Ural Mountains, Russia, Switzerland, Tanzania and Kenya. However, you can find just a few resources of gem quality crystals. An amount that is small of material has come from Asbestos, Quebec, Canada. Recent finds in Tanzania and Kenya have brought some very nicely colored gems to the market. One way to obtain the product is from California, USA and has been Californite that is nick-named or Jade. This bright opaque that is green translucent product arises from near Happy Jack mine, Siskiyou County and near Pulga, Butte County, California.

Category: Sorosilicate
Chemical Formula: Ca19Al4Fe(Al,Mg,Fe)8Si18O7
Calcium Aluminum Iron Silicate
Molecular Weight: 1,422.09 gm
Composition: Calcium 28.18 % Ca 39.43 % CaO
Magnesium 3.42 % Mg 5.67 % MgO
Aluminum 7.59 % Al 14.34 % Al2O3
Silicon 17.77 % Si 38.03 % SiO2
Hydrogen 0.28 % H 2.53 % H2O
Oxygen 42.75 % O
  100.00 % 100.00 % = TOTAL OXIDE


Crystallography: Tetragonal – Dipyramidal
Crystal Habit: Crystals commonly as short pyramidal to long prismatic crystals, to 15 cm, morphologically complex, with up to 30 forms reported on one crystal; columnar, granular, massive. Californite is found in massive form, not as crystals.
Twinning: Twinned domains observed at a very fine scale.


Cleavage: Indistinct on {110}, {100} and {001]
Fracture: Irregular/Uneven, Sub-conchoidal
Tenacity: Brittle
Moh’s Hardness: 6.0 – 7.0
Density: 3.32 – 3.47 (g/cm3)
Luminescence: None
Radioactivity: Not Radioactive


Color: Green, Brown, Colorless to White, Blue (Cyprine), Violet, Bluish green, Pink, Red, Black, commonly zoned; in transmitted light, Colorless to light Yellow, Green, Brown
Transparency: Transparent, Translucent
Luster: Vitreous, Resinous
Refractive Index: 1.698 – 1.742  Uniaxial ( -/+ ) and Biaxial
Birefringence: 0.0040 – 0.0060
Dispersion: Strong; 0.019 – 0.025
Pleochroism: Weak; O = colorless to yellowish, E = yellowish, greenish, brownish