Rainbow Moonstone

Feldspar

By Tim Matthews, JD, FGA, GG, DGA,
CEO and President of JTV (retired)
Published: June 2014
Modified: September 2023
Rainbow Moonstone Polished Rainbow Moonstone Rough Rainbow Moonstone Jewelry

Rainbow moonstone is a term sometimes used to describe fine colorless, transparent labradorite that displays a rainbow-colored iridescence. Internally repeating feldspar layers scatter the light that enters the stone creating a mystical blue glow that reminds one of moonbeams known as adularescence.

General Information

Common Name
Rainbow Moonstone
Species
Feldspar
Transparency
Translucent-Transparent
Dispersion
Strength: None
Refractive Index
1.559-1.568
Birefringence
0.009
Optic Character
Biaxial
Optic Sign
Positive
Polariscope Reaction
Aggregate (AGG), Doubly Refractive (DR)
Fluorescence
SWUV: weak pinkish orange
LWUV: moderate chalky blue
CCF Reaction
None
Pleochroism
Unobservable
Hardness
6-6.5
Streak
White
Specific Gravity
2.650-2.750
Toughness
Poor
Inclusions
Moonstone occasionally contains colorless inclusions and might show parallel multiple twinning planes.
Luster
Vitreous
Stability
Good
Fracture
Uneven, Splintery
Cleavage
Perfect, in two directions
Chemical Name
calcium, sodium aluminum silicate
Chemical Formula
NaAlSi3O8 and CaAl2Si2O8
Crystal System
Triclinic
Chemistry Classification
Silicate

Rainbow Moonstone Colors

  • Gray Rainbow Moonstone
    Gray
  • White Rainbow Moonstone
    White

Alternate Names

Labradorite Moonstone

Countries of Origin

Unknown; Sri Lanka; Brazil; Madagascar; India

Care

Normal Care