Rainbow Moonstone
Feldspar Group - Orthoclase/Albite Intergrowth (Commercial name: Rainbow Moonstone, technically White Labradorite) · Semi-Precious Gemstone
Crystal System
Triclinic, typically found in massive, granular, or tumbled forms
Mineral Group
Silicates (Subgroup: Tectosilicates, Feldspar group)
Chemical Formula
(Na,Ca)(Al,Si)4O8
Formation Process
Igneous and pegmatitic formation, specifically crystallizing from cooling magma or hydrothermal solutions, where intergrowth of albite and orthoclase creates lamellae
About This Crystal
A polished, tumbled smooth specimen that is predominantly off-white to translucent grey with a characteristic pearly sheen and distinctive dark black tourmaline or biotite inclusions clustered at one corner
Physical Characteristics
White to grey body color with a white streak, perfect cleavage in two directions at nearly 90 degrees, uneven to conchoidal fracture, specific gravity around 2.68 to 2.72, brittle tenacity, and typically inert under UV light
Optical Properties
Biaxial positive with a refractive index ranging from 1.525 to 1.560, displaying strong adularescence (schiller effect) caused by light scattering between alternating layers of albite and orthoclase
Hardness & Durability
Origin Region
Madagascar, India, Sri Lanka, Australia, and the United States
Hardness & Durability
Mohs hardness of 6 to 6.5, moderate toughness, sensitive to sharp blows due to distinct cleavage, fair stability requiring care in jewelry settings
Care & Maintenance
Clean with warm soapy water and a soft cloth, avoid ultrasonic and steam cleaners, harsh chemicals, and prolonged exposure to direct sunlight
Rarity & Value
Common to Uncommon, value depends on the intensity of adularescence, transparency, and lack of distracting dark inclusions, though black inclusions are sometimes prized for contrast; generally affordable
Special Characteristics
Displays adularescence (a milky, bluish shimmer floating across the surface) and features contrasting black mineral inclusions
Lore & History
Associated with lunar energies, intuition, and feminine balancing in modern crystal healing; traditionally linked to the third eye and crown chakras, promoting inner growth and strength