Iolite
Also Cordierite, Water sapphire
Violet-blue cordierite that changes colour as you turn it.
- Family
- Cordierite
- Formula
- (Mg,Fe)₂Al₄Si₅O₁₈
- Mohs
- 7 to 7.5
- System
- Orthorhombic
Drag to turn
Science
Iolite is the gem name for cordierite, a magnesium aluminium silicate of metamorphic rocks. It is among the most pleochroic gems: violet-blue in one direction, near colourless in another, yellowish in the third. Cutters must orient the rough carefully or the stone goes grey.
- Mineral
- Cordierite
- Formula
- (Mg,Fe)₂Al₄Si₅O₁₈
- Crystal system
- Orthorhombic
- Mohs hardness
- 7 to 7.5
- Specific gravity
- 2.61
- Refractive index
- 1.542 to 1.551
- Lustre
- Vitreous
- Colours
- Violet-blue, Grey, Yellow
Composition
(Mg,Fe)₂Al₄Si₅O₁₈. Made of Magnesium, Iron, Aluminium, Silicon, Oxygen.
Origin
- IndiaOdisha
- Sri Lanka
- Madagascar
- Brazil
- Tanzania
- Norway
Filled dots are primary sources
Rarity
Moderately available and inexpensive; clean stones over five carats are less common.
- 1 Abundant
- 2 Common
- 3 Uncommon
- 4 Rare
- 5 Exceptional
Hardness
Iolite sits at 7 to 7.5 on the Mohs scale. It will scratch glass and holds a polish in daily wear.
Energy
Associations from crystal-healing tradition, recorded here as folklore. They are not medical claims.
Chakras
- Third Eye
- Throat
Element
- Air
Zodiac
- Sagittarius
- Taurus
- Libra
Planets
- Moon
- Saturn
Properties
- Vision
- Inner journeys
- Leadership
- Sobriety
Lore
The Viking 'sunstone' that located the sun through cloud is sometimes claimed to be iolite, whose pleochroism polarises light; the historical evidence favours Iceland spar, but the story sticks.
In modern practice it is the stone of inner sight and of sober, clear guidance.
- NameFrom the Greek ios, violet.
- PleochroismThree distinct colours; the strongest of any common gem.