Moonstone
Feldspar group, Orthoclase / Albite var. Moonstone · Semi-Precious Gemstone and Mineral Specimen
Crystal System
Monoclinic; typically found as a tumbled or polished cabochon in this specimen form
Mineral Group
Silicates, specifically Tectosilicates (Feldspar group)
Chemical Formula
(K,Na)AlSi3O8
Formation Process
Igneous and hydrothermal processes, crystallizing slowly from cooling magma or hydrothermal solutions in pegmatites, allowing microscopic intergrowths of orthoclase and albite
About This Crystal
A smooth, tumbled, polished cabochon-style specimen with a whitish to translucent body color, exhibiting a subtle glowing optical phenomenon characteristic of adularescence across its surface
Physical Characteristics
Color ranges from white to silvery-grey with translucent clarity; white streak; perfect cleavage in two directions at or near right angles; uneven to conchoidal fracture; specific gravity around 2.56-2.58; brittle tenacity; generally inert to weak fluorescence under UV light
Optical Properties
Biaxial negative optical character, refractive index ranging from 1.518 to 1.525, double refraction (birefringence) around 0.005-0.008, displaying strong adularescence (a floating billowy light effect caused by light scattering between alternating layers of orthoclase and albite)
Hardness & Durability
Origin Region
Sri Lanka, India, Madagascar, Myanmar, Australia, and the United States; typically forms in igneous pegmatites and granitic rocks
Hardness & Durability
Mohs hardness of 6 to 6.5; fair to good toughness but possesses distinct cleavage planes making it vulnerable to hard impacts and sudden temperature changes; moderate wearability for jewelry, best set in protective mountings
Care & Maintenance
Clean with warm soapy water and a soft cloth; avoid ultrasonic or steam cleaners, harsh chemicals, and sudden thermal shock; store separately to prevent scratching by harder gemstones like quartz
Rarity & Value
Common to Uncommon depending on the quality and intensity of adularescence and body clarity; value increases with strong blue adularescence, transparency, and lack of dark inclusions; typically affordable to moderate price range
Special Characteristics
Displays prominent adularescence (schiller or moonlike glow) due to the interference of light waves reflecting from microscopic lamellar intergrowths of two different feldspar types
Lore & History
Historically associated with lunar deities and ancient Roman and Greek folklore, where it was believed to be solidified moonbeams. In modern crystal healing, it is traditionally connected to the Third Eye and Crown chakras, symbolizing intuition, emotional balance, and new beginnings (noted as traditional beliefs rather than scientific facts)