Rainbow Moonstone
Plagioclase Feldspar var. Labradorite (White) · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Triclinic; typically found in massive forms or as rounded tumbled stones showing internal twinning planes.
Mineral Group
Silicates (Tectosilicates); Feldspar group; Plagioclase series.
Chemical Formula
(Na,Ca)(Al,Si)4O8 with common inclusions of Black Tourmaline (Schorl)
Formation Process
Igneous formation via slow cooling of magma, where alternating layers of albite and anorthite create the conditions for light interference.
About This Crystal
A translucent to opaque white-grey stone with a vitreous to pearly luster. This specific specimen is a tumbled stone featuring visible black inclusions (Schorl) against a milky white background. It exhibits a subtle schiller effect.
Physical Characteristics
Color: White/Grey with black spots; Streak: White; Cleavage: Perfect in two directions at 90 degrees; Density: 2.6 – 2.7; Fluorescence: Weak bluish-white under longwave UV.
Optical Properties
Exhibits adularescence (a blue or multi-colored 'glow') caused by light scattering from internal lamellar structures. Refractive Index: 1.540 – 1.553; Biaxial positive.
Hardness & Durability
Origin Region
Primarily Bihar, India and Madagascar; forms in plutonic igneous rocks and pegmatites.
Hardness & Durability
Mohs Hardness: 6.0 – 6.5. Fairly brittle with perfect cleavage, making it prone to cracking if struck. Moderate wearability.
Care & Maintenance
Clean with warm soapy water and a soft brush. Avoid ultrasonic cleaners, steam cleaning, and harsh chemicals. Store separately to prevent scratching from harder gems.
Rarity & Value
Relatively common in commercial markets. Value is determined by the strength and color of the adularescence (blue flash is most prized), clarity, and size.
Special Characteristics
Labradorescence/Adularescence; contains prominent black tourmaline inclusions which create a 'Dalmatian' or 'Spotted' aesthetic.
Lore & History
Historically associated with lunar deities and protection for travelers. In modern crystal healing lore, it is believed to represent new beginnings, inner growth, and emotional balance, often linked to the Crown and Third Eye chakras.