Moonstone
Feldspar group, Orthoclase var. Moonstone · Semi-Precious Gemstone and Mineral Specimen
Crystal System
Monoclinic; massive to blocky crystal habit with typical cleavage planes
Mineral Group
Silicates, specifically Tectosilicates (Feldspar group)
Chemical Formula
KAlSi3O8
Formation Process
Igneous and pegmatitic crystallization, where orthoclase and albite exsolve into alternating microscopic layers during cooling, causing light scattering
About This Crystal
A small, rough mineral specimen featuring a milky-white body color with a pearly to vitreous luster, translucent to opaque transparency, and darker matrix or inclusions at the base
Physical Characteristics
White body color with greyish-black matrix at the base, white streak, two directions of good cleavage at or near 90 degrees, uneven to conchoidal fracture, specific gravity around 2.56-2.58, and brittle tenacity
Optical Properties
Biaxial negative with refractive indices between 1.518 and 1.526, low birefringence, and displays adularescence (a billowy, moonlight-like sheen caused by light scattering between alternating feldspar lamellae)
Hardness & Durability
Origin Region
India, Madagascar, Sri Lanka, Myanmar, and the United States; typically forms in igneous pegmatites and granitic rocks
Hardness & Durability
Mohs hardness of 6, fair to good cleavage making it vulnerable to hard impacts, moderate durability suitable for pendants and earrings but requires care in rings
Care & Maintenance
Clean with warm soapy water and a soft brush; avoid ultrasonic cleaners, steam cleaners, and harsh chemicals; store separately to prevent scratching by harder stones
Rarity & Value
Common to Uncommon depending on clarity and the strength of adularescence; value increases with strong blue sheen, high transparency, and lack of dark inclusions; typically affordable as rough specimens
Special Characteristics
Adularescence, which creates a floating shimmering light effect due to the intergrowth of albite and orthoclase micro-layers
Lore & History
Historically associated with lunar deities in ancient Roman and Greek civilizations, often linked in modern crystal lore with intuition, emotional balance, and the third eye or crown chakras (traditional beliefs, not scientific claims)