White Moonstone — Properties, Meaning, and Uses

White moonstone is the most recognized variety of orthoclase feldspar, valued in jewelry for its adularescence: a floating bluish or white sheen that appears to move beneath the surface as the stone is turned. With a hardness of 6 to 6.5 Mohs, it is suitable for pieces protected with a closed bezel setting. The best specimens come from Sri Lanka and India. Property Value Mineralogical name Adularia (Orthoclase) Chemical formula KAlSi₃O₈ Mineral group Tectosilicates → Feldspars → Orthoclase Crystal system Monoclinic Hardness (Mohs) 6–6.5 Density 2.56–2.59 g/cm³ Luster Vitreous to pearly Fracture Conchoidal to irregular Color White, colorless, grayish, peach Streak White Diaphaneity Translucent to transparent Optical phenomenon Adularescence Main deposits Sri Lanka, India, Myanmar, Madagascar, Australia What is white moonstone? White moonstone is a variety of orthoclase feldspar (KAlSi₃O₈) within the tectosilicate group. The name "adularia" comes from the Adula massif in the Swiss Alps, where the first reference specimens were found in the 18th century. In the gemological trade, the terms "adularia," "piedra de luna" (Spanish for moonstone), and "moonstone" coexist, all referring to the same species with the optical phenomenon of adularescence. Adularescence originates from the alternation of submicroscopic layers of orthoclase and albite formed during the slow cooling of the rock. When light penetrates these layers, it scatters in different directions, creating the characteristic sheen that floats beneath the surface. The intensity of the effect depends on the thickness and regularity of the layers: the more uniform they are, the more pronounced and centered the sheen. The name "moonstone" encompasses several feldspar species with similar optical phenomena on the market. The rainbow variety corresponds to labradorite, with multicolored labradorcence; the white and peach varieties correspond to orthoclase with different impurity contents. Each has its own physical properties and is described in separate guides. Physical and chemical properties Composition and crystal structure Orthoclase is a potassium aluminosilicate with a three-dimensional structure of SiO₄ and AlO₄ tetrahedra linked by vertices. It crystallizes in the monoclinic system; adularia is the low-temperature variety, stable under hydrothermal conditions at less than 500 °C. Sanidine, the high-temperature variety, is isometric. Exsolution lamellae of albite within orthoclase — visible only with an electron microscope — are responsible for adularescence. Hardness, toughness, and durability With 6–6.5 Mohs, moonstone is scratched by harder minerals such as quartz (7 Mohs) or sapphire. It has two cleavage planes almost perpendicular to each other, a legacy of the feldspar system, which reduces its toughness against lateral impacts. In jewelry, a closed or semi-bezel setting is recommended to protect the edges. More information in jewelry care. Optical properties The refractive index ranges from 1.518 to 1.526, with low birefringence (0.005–0.008). In a gemological refractometer, it is easily distinguished from glass (isotropic, single RI) and calcite (much higher birefringence). Adularescence appears most intensely when the cabochon is oriented with the table perpendicular to the optical axis of the layers. Fluorescence Under long-wave UV light, many specimens show weak to moderate orange-red or light blue fluorescence. This characteristic is useful for distinguishing natural stone from glass imitations, which usually do not fluoresce or do so differently. Varieties of moonstone The market distinguishes four commercial varieties of "moonstone," with different base minerals: Variety Actual mineral Phenomenon Main origin White moonstone Orthoclase (adularia) White or blue adularescence Sri Lanka, India Rainbow moonstone Labradorite Multicolored labradorescence India, Madagascar Peach moonstone Orthoclase with impurities Soft orange adularescence India, Tanzania Black moonstone Dark labradorite Blue adularescence on a black background India The rainbow variety has its own complete guide to rainbow moonstone in this encyclopedia. Where is white moonstone found? Sri Lanka (Meetiyagoda, Southern Province) is historically the source of the best specimens: translucent adularia with intense blue adularescence, produced in pegmatite veins and associated alluvium. India (Tamil Nadu, Rajasthan, Andhra Pradesh) supplies the bulk of current commercial material, with variable quality ranging from opaque to semi-translucent. Myanmar produces remarkably transparent specimens, including the "cat's eye moonstone" variety with chatoyance. Madagascar has grown as an important source since the nineties with good quality material. Australia (Queensland) offers moonstone with yellow and brown tones. The Alpine deposits of Switzerland and Italy, where the first reference adularias were described, are now virtually exhausted. Uses of white moonstone In jewelry and lapidary Moonstone is almost exclusively cut as a cabochon to take advantage of adularescence. The cut must orient the table perpendicular to the optical axis of the layers to maximize the effect. The most common shapes are oval and round, although it is also carved into free forms for artisanal pieces and into drops for pendants. For 925 silver jewelry, the closed bezel setting is the most suitable given the mineral's cleavage profile. The white moonstone cabochon is one of the most requested by jewelers. It is also used in earrings set with silver wire (wire wrap), where the stone can be showcased without pressure on the edges. For everyday rings, a deep bezel setting is essential. In decoration and collecting Prismatic adularia crystals with visible adularescence on matrix rock — combined with green chlorite or epidote — are highly valued alpine collector's items. Moon-shaped carvings or polished oval figures are used as decorative objects in spiritual crystalware. White moonstone in cultural and spiritual tradition The properties described in this section belong to the cultural tradition of crystal therapy and do not constitute medical advice. History and ancestral uses In India, moonstone has been revered for more than two millennia: Hindu tradition attributes its origin to the moon and considers its flashes as solidified moonbeams. Pliny the Elder, in the 1st century AD, described a stone that showed the figure of the waxing or waning moon according to the lunar cycle — a description that historians identify with adularia from Sri Lanka. In the Art Nouveau movement of the late 19th century, jewelers such as René Lalique and Louis Comfort Tiffany integrated it into their designs, fostering a revival of its use in Europe. In Arab and Celtic cultures, it was attributed the function of a travelers' amulet, especially on sea voyages. Meaning in different cultures In medieval Europe, it was associated with Diana and Selene, lunar goddesses, and with cycles of transformation. Medieval lapidaries prescribed it as a stone of intuition and travel. In contemporary India, it remains popular as a wedding gift and as a birthstone for those born in June. Attributed properties in crystal therapy White moonstone (intuitive wisdom and emotional balance) holds a central place in modern crystal therapy. It is attributed qualities of emotional calm, intuitive openness, and support during times of change or transition. Tradition links it to the feminine principle and cycles of initiation; therefore, it is frequently used in new moon rituals. Chakras and associations Chakra Element Planet Signs Crown (Sahasrara), Third Eye (Ajna) Water Moon Cancer, Scorpio, Pisces How to identify authentic white moonstone Basic tests Genuine adularescence moves as the stone is turned: the sheen appears to slide beneath the surface; it is not fixed on it. In imitation glass, the sheen is usually superficial and static. Natural stone feels cool to the touch and takes longer to reach body temperature than glass. With a refractometer, indices of 1.518–1.526 and low birefringence (0.005–0.008) distinguish adularia from glass (isotropic) and calcite (very high birefringence). The density of 2.56–2.59 g/cm³ is another confirmation parameter. Common confusions The most frequent imitations are opalescent glass, quartz with blue treatment, and opalite (synthetic manganese glass). Rainbow moonstone (labradorite) is sometimes sold as "moonstone" without qualification, which is not commercially incorrect, but it has a higher RI (1.559–1.573) and more pronounced cleavage. Labradorite has its own guide in this encyclopedia. Care and maintenance Cleaning Clean with a soft cloth and warm water with mild soap. Avoid ultrasonic cleaners and steam, which can aggravate microfissures in the cleavage planes. Acidic or abrasive detergents attack the feldspar surface. Dry immediately after contact with water to prevent lime deposits. Storage and precautions Store separately from harder minerals (quartz, garnet, sapphire) to prevent scratching. Wrapping in a soft cloth or an individual box is the safest option. Do not expose to prolonged intense direct sunlight. For jewelry pieces, a closed bezel setting protects the fragile edges of the feldspar. White moonstone at Anima Mundi Crystals At Anima Mundi Crystals, we select white moonstone cabochons with visible adularescence and document the origin when possible. You will find pieces in our cabochons section and in all jewelry. For 925 silver jewelry, our silversmithing section includes specific selections for setting. Frequently asked questions about white moonstone What is the difference between white moonstone and rainbow moonstone? White moonstone is orthoclase (KAlSi₃O₈) with white or soft blue adularescence, while rainbow moonstone is labradorite with multicolored labradorescence. Although they share the commercial name "moonstone," they have distinct chemical compositions, different refractive indices, and cleavage planes with different angles. Labradorite has a higher RI (1.559–1.573). Can it be used in rings? Yes, with reservations. Its hardness of 6–6.5 Mohs and perfect cleavage make it vulnerable to lateral impacts. For everyday rings, a deep closed bezel setting is essential. Rings for occasional use or cocktail rings present less risk. It is not the most robust stone for daily wear rings. Why does it have that moving sheen? Adularescence is caused by the scattering of light between alternating layers of orthoclase and albite formed during the slow cooling of the rock. The layers are tens of nanometers thick and scatter light differently depending on the angle of incidence, creating the floating sheen. The more uniform the layers, the more pronounced and centered the effect. How is it cleaned? With a soft cloth and warm water with mild soap. No ultrasonic cleaners, no steam, no acidic products. Dry thoroughly afterward. Avoid prolonged exposure to direct sunlight for specimens with very thin layers. Do not use baking soda or vinegar on the surface. Where does the best white moonstone come from? Sri Lanka (Meetiyagoda, Southern Province) historically produces the best specimens: translucent adularia with intense blue adularescence. India and Myanmar are currently the most active commercial sources. Alpine specimens from Switzerland are rare collector's items. How much does a white moonstone cabochon cost? The price varies depending on the intensity of the adularescence, transparency, and origin. A standard Indian cabochon measuring 5×7 mm costs between 1 and 5 euros. A Sri Lankan specimen with centered blue adularescence and translucent material can exceed 20–50 euros per carat in gem sizes. High-transparency specimens from Myanmar are the most valued. What does it mean in spiritual tradition? In crystal therapy tradition, it is associated with intuition, cycles of change, and emotional balance. It is linked to the moon, the water element, and the crown and third eye chakras. In India, its ritual and symbolic use has been documented for more than two millennia. Recommended bibliography Gienger, M. (1998). Crystal Power, Crystal Healing. Blandford Press. Simmons, R., & Ahsian, N. (2005). The Book of Stones. Heaven & Earth Publishing. Deer, W. A., Howie, R. A., & Zussman, J. (1992). An Introduction to the Rock-Forming Minerals. Longman. Gemological Institute of America (GIA) — Moonstone: gia.edu/moonstone Mindat.org — Adularia: mindat.org/min-29248

White Moonstone — Properties, Meaning, and Uses

Anima Mundi CrystalsJun 6, 2026

Information

Property	Value
Mineralogical name	Adularia (Orthoclase)
Chemical formula	KAlSi₃O₈
Mineral group	Tectosilicates → Feldspars → Orthoclase
Crystal system	Monoclinic
Hardness (Mohs)	6–6.5
Density	2.56–2.59 g/cm³
Luster	Vitreous to pearly
Fracture	Conchoidal to irregular
Color	White, colorless, grayish, peach
Streak	White
Diaphaneity	Translucent to transparent
Optical phenomenon	Adularescence
Main deposits	Sri Lanka, India, Myanmar, Madagascar, Australia