Feldspar • Orthoclase / Albite Intergrowth (Alkali Feldspar)

Moonstone

Colorless, milky white, peach, or gray body color showing a floating blue or silvery billowy light sheen (adularescence) caused by light diffraction across microscopic alternating orthoclase and albite layers.

(K,Na)AlSi₃O₈ (Potassium-Sodium Aluminum Silicate lamellar intergrowth)Mohs 6.0 – 6.5 Mohs

Mineralogical & Gemological Profile

Mineral FamilyFeldspar
Mineral SpeciesOrthoclase / Albite Intergrowth (Alkali Feldspar)
Gemological VarietyMoonstone
Chemical Composition(K,Na)AlSi₃O₈ (Potassium-Sodium Aluminum Silicate lamellar intergrowth)
Crystal SystemMonoclinic / Triclinic
Mohs Hardness6.0 – 6.5 Mohs
Specific Gravity2.56 – 2.59
Refractive Index1.518 – 1.526

Color Characteristics & Optical Behavior

Colorless, milky white, peach, or gray body color showing a floating blue or silvery billowy light sheen (adularescence) caused by light diffraction across microscopic alternating orthoclase and albite layers.

Geological Context & Pakistani / Global Localities

Forms in pegmatites and high-grade metamorphic rocks in Sri Lanka, India, Myanmar, and alpine clefts.

Collector Interest & Rarity Factors

Transparent colorless cabochons exhibiting a centered, three-dimensional royal-blue adularescence are the pinnacle of collector moonstones.

Fine Jewelry Applications

High-domed cabochon pendants, earrings, and protective bezel-set rings.

Treatment Considerations & Disclosure

Natural moonstone is untreated; beware of coated glass or opalite imitations.

Care & Cleaning Instructions

Has two directions of cleavage and 6.0–6.5 Mohs hardness; protect from knocks and never use ultrasonic or steam cleaners.

Traditional Meaning

Traditional Symbolism & Cultural Heritage

Revered in Roman and Indian traditions as solidified moonlight, symbolizing intuition, safe travel, and calm. Traditional June birthstone.

Note: Cultural and birthstone traditions are presented strictly as historical folklore, never as scientifically verified medical or metaphysical effects.

Feldspar

Related Entries

Feldspar

Sunstone

6.0 – 6.5 Mohs
Sunstone

Warm golden, peach, or coppery-red body color sparkling with metallic schiller (aventurescence) from aligned specular hematite or copper...

Chemical formula
(Na,Ca)(Al,Si)₄O₈ with Hematite or Native Copper platelets
Feldspar

Labradorite

6.0 – 6.5 Mohs
Labradorite

Smoky dark gray body color flashing electric iridescent peacock blue, gold, green, and violet (labradorescence) via lamellar interference.

Chemical formula
(Ca,Na)(Al,Si)₄O₈ (50–70% Anorthite, 30–50% Albite)
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