Yellow Moonstone
Feldspar group, Orthoclase variety Moonstone · Semi-Precious Gemstone and Mineral Specimen
Crystal System
Monoclinic system, typically forming prismatic crystals or rounded tumbled pebble shapes
Mineral Group
Silicates, specifically Tectosilicates (Feldspar group)
Chemical Formula
KAlSi3O8 (Potassium aluminum silicate with sodium substitutions)
Formation Process
Igneous and pegmatitic formation, where orthoclase and albite intergrow and slowly cool to form microscopic lamellae that scatter light
About This Crystal
A tumbled, smooth, and polished pebble of translucent yellow-to-peach moonstone displaying a soft pearly luster and a characteristic shimmering adularescence
Physical Characteristics
Color ranges from pale yellow to warm peach; white streak; no true cleavage visible on tumbled surface; uneven to conchoidal fracture; specific gravity around 2.56-2.58; brittle tenacity; generally non-fluorescent under standard UV
Optical Properties
Biaxial negative with double refraction; refractive index ranges from 1.518 to 1.526; displays prominent adularescence (a milky, billowy floating light effect caused by light scattering between alternating layers of orthoclase and albite)
Hardness & Durability
Origin Region
Found in India, Sri Lanka, Madagascar, Myanmar, and the United States, typically in pegmatites and igneous rocks
Hardness & Durability
Mohs hardness of 6 to 6.5; moderate toughness; sensitive to sudden temperature changes and hard knocks due to cleavage planes; requires care when worn in rings
Care & Maintenance
Clean with warm soapy water and a soft brush; avoid ultrasonic cleaners, harsh chemicals, and steam cleaning; store separately in a soft pouch to prevent scratching by harder stones
Rarity & Value
Common to uncommon depending on the intensity of adularescence and body color; valuable specimens show strong, centered floating light effects with minimal internal fractures; generally affordable price range
Special Characteristics
Displays adularescence, a unique optical phenomenon where light diffuses through microscopic layered structures, creating a glowing moon-like sheen across the surface
Lore & History
Historically associated with lunar deities and ancient Roman and Greek lore; believed by crystal practitioners to promote inner growth, emotional balance, intuition, and calm energy, connected primarily to the solar plexus and sacral chakras