Moonstone
Feldspar with a floating blue sheen, from layers thinner than light.
- Family
- Feldspar
- Formula
- KAlSi₃O₈
- Mohs
- 6 to 6.5
- System
- Monoclinic
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Science
Moonstone is orthoclase feldspar layered with albite as the two unmixed on cooling. The layers are thin enough to scatter blue light, producing adularescence, a glow that moves beneath the surface. 'Rainbow moonstone' is actually labradorite.
- Mineral
- Feldspar (variety)
- Formula
- KAlSi₃O₈
- Crystal system
- Monoclinic
- Mohs hardness
- 6 to 6.5
- Specific gravity
- 2.58
- Refractive index
- 1.518 to 1.526
- Lustre
- Vitreous to pearly
- Colours
- Colourless, White, Peach, Grey
- Birthstone
- June
Composition
KAlSi₃O₈. Made of Potassium, Aluminium, Silicon, Oxygen, with trace Sodium responsible for colour.
Origin
- Sri LankaMeetiyagoda
- India
- MyanmarMogok, historic blue sheen
- Madagascar
- Tanzania
- SwitzerlandAdula Alps, adularia
Filled dots are primary sources
Rarity
Common as milky material. Transparent stones with a strong blue sheen, once from Mogok, are now rare.
- 1 Abundant
- 2 Common
- 3 Uncommon
- 4 Rare
- 5 Exceptional
Hardness
Moonstone sits at 6 to 6.5 on the Mohs scale. Glass and a knife blade are about as hard; it wears well with care.
Energy
Associations from crystal-healing tradition, recorded here as folklore. They are not medical claims.
Chakras
- Crown
- Third Eye
- Sacral
Element
- Water
Zodiac
- Cancer
- Libra
- Scorpio
Planets
- Moon
Properties
- Intuition
- Cycles
- Fertility
- New beginnings
- Emotional balance
Lore
Romans thought it was moonlight solidified; Hindu tradition sets it in the forehead of the moon god. Pliny wrote that its image waxed and waned with the moon.
René Lalique and the Art Nouveau jewellers made it their signature stone around 1900; Florida named it state gem in 1970 for the moon landing, although none is found there.
- AdularescenceLight scattering from alternating orthoclase and albite layers.
- AdulariaNamed for Mount Adula in the Swiss Alps, an early source.