Moonstone-Labradorite | Gemopedia

Moonstone is a variety of feldspar that displays an amazing optical phenomenon called, adularescence. Internallyrepeating feldspar layers scatter the light that enters the stone creating a mystical glow reminiscent of moonbeams.This glow comes to life, rolling across the gems surface, when it is moved. Adularescent labradorite with a multi-colored glow is sometimes called Rainbow Moonstone.
Alternate
Names
Rainbow Moonstone
Colors
Colorless, White, Slight Orange, Green With Blue Sheen

Moonstone-Labradorite Classification

Common Name

Moonstone-Labradorite

Species

Labradorite

Variety

Moonstone

Colors

Colorless, White, Slight Orange, Green With Blue Sheen

Alternate Names

Rainbow Moonstone

Gemstone Groups

Feldspar

Key Separations

refractive index, fracture, fluorescence and maybe birefringence.

Comments

Moonstone describes a near colorless variety of labradorite feldspar when adularescence in the appearance of a blue sheen is observable.

Moonstone-Labradorite Optical Properties

Transparency

Transparent - Translucent

Refractive Index

1.559-1.568

Birefringence

0.009-0.009

Optic Character

Biaxial

Optic Sign

Positive

Polariscope Reaction

Doubly Refractive (DR)

Fluorescence

SWUV: weak pinkish orange
LWUV: moderate chalky blue

CCF Reaction

Pleochroism

Unobservable

Dispersion

Comments

Moonstone-Labradorite Chemistry & Crystallography

Chemical Name

calcium, sodium aluminum silicate

Chemical Formula

NaAlSi3O8 and CaAl2Si2O8

Synthesis

Crystal System

Triclinic

Classification

Silicate

Nature

Natural

Crystallinity

Crystalline

Comments

Moonstone-Labradorite Characteristic Physical Properties

Hardness

6-6.5

Streak

White

Specific Gravity

2.65-2.75 Range:+/-0.05 Typical:2.69

Toughness

Poor

Inclusions

Moonstone occasionally contains colorless inclusions and might show parallel multiple twinning planes.

Luster

Vitreous

Stability

Fracture

Uneven, Splintery

Cleavage

Perfect, in two directions

Comments

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