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Idocrase

Vesuvianite

By Tim Matthews, JD, FGA, GG, DGA,
CEO and President of JTV (retired)
Published: June 2014
Modified: September 2023
Idocrase Polished Idocrase Rough Idocrase Jewelry
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Table of Contents
  • General Information
  • Idocrase Colors
  • Alternate Names
  • Countries of Origin
  • Care

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.

General Information

  • Classification
  • Optical Properties
  • Characteristic Physical Properties
  • Chemistry & Crystallography
Common Name
Idocrase
Species
Vesuvianite
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
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
Chemical Name
calcium magnesium aluminum silicate
Chemical Formula
Ca10Mg2Al4(SiO4)5(Si2O7)2(OH)4
Crystal System
Tetragonal
Chemistry Classification
Silicate

Idocrase Colors

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

Alternate Names

Vesuvianite, Californite, Xanthite, Cyprine

Countries of Origin

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

Care

Moderately soft, so be mindful of scratching.

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