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Idocrase, also known as vesuvianite after its discovery at Mount Vesuvius, has crystals that are prismatic and glassy. It is usually green or chartreuse in color, but may be found in yellow to brown, yellow-green, red, black, blue or purple hues.

Idocrase Polished
Idocrase Classification
Common Name Idocrase
Species Vesuvianite
Idocrase Optical Properties
Transparency Opaque-Opaque
Dispersion Strength: Weak Fire Value: 0.019
Refractive Index 1.700-1.746 Tolerance: (+0.003/-0.013)
Birefringence 0.003- 0.006
Optic Character Uniaxial
Optic Sign Positive or Negative
Polariscope Reaction Aggregate (AGG), Doubly Refractive (DR)
Fluorescence SWUV: inert to yellow
LWUV: inert
Pleochroism Dichroic, unobservable or weak, varying shades of body color
Idocrase Characteristic Physical Properties
Hardness 6-7
Streak White
Specific Gravity 3.250-3.500 Typical:3.400
Toughness Varies
Luster Vitreous, Resinous, Greasy
Fracture Conchoidal, Granular, Uneven
Cleavage Poor, in three directions
Idocrase Chemistry & Crystallography
Chemical Name calcium magnesium aluminum silicate
Chemical Formula Ca10Mg2Al4(SiO4)5(Si2O7)2(OH)4
Crystal System Tetragonal
Chemistry Classification Silicate

Idocrase Colors

  • Purple Idocrase Purple
  • Green Idocrase Green
  • Brown Idocrase Brown
  • Yellow Idocrase Yellow
  • Black Idocrase Black
  • White Idocrase White
  • Red Idocrase Red
  • Blue Idocrase Blue

Alternate Names

Vesuvianite, Californite, Xanthite, Cyprine

Countries of Origin

Myanmar; Cameroon; Papua New Guinea; Malaysia; Kazakhstan; Portugal; Greece; Austria; Mongolia; Korea (the Republic of); Morocco; Mali; Brazil; Argentina; United States of America (the); Hungary; Japan; Taiwan (Province of China); India; New Zealand; Canada; Turkey; Namibia; Finland; Italy; South Africa; Antarctica; Jamaica; Peru; Germany; Afghanistan; Czechia; Madagascar; Thailand; Sweden; Pakistan; China; Ireland; Russian Federation (the); Poland; Sudan (the); Slovakia; Bulgaria; France; Serbia; Kyrgyzstan; United Kingdom of Great Britain and Northern Ireland (the); Cote D'Ivoire; Romania; Uzbekistan; Kenya; Switzerland; Spain; Cuba; Norway; Mexico; Philippines (the); Australia; Greenland; Montenegro; Tajikistan; Indonesia


Moderately soft, so be mindful of scratching.

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Tim Matthews

Tim Matthews is President and Chief Executive Officer of Jewelry Television® (JTV), as well as a member of the company's Board of Directors. He oversees and leads all aspects of the company's powerful omni-digital retail platform that uniquely specializes in fine jewelry and gemstones. His passion for business and gemstones has led him to become a recognized expert in the field of gemology. He is a life member of the Gemmological Association of Great Britain (Gem-A) and has earned Gem-A's highest degrees, the Gemmology (FGA) and Diamond (DGA) diplomas. He is also a Graduate Gemologist (GG) of the Gemological Institute of America (GIA) and has also completed GIA's Graduate Diplomas in Diamonds, Colored Stones and Pearls. Under his leadership, JTV has become the leader in the sourcing and selling of color gemstones and jewelry.

This page was created on June 27, 2014.

This page was last edited on October 24, 2019.