Moonstone identification and geology

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• Labradorite
• Opal
• Chalcedony

Sources, scope & corrections

These authoritative resources support category-level nomenclature, terminology, identification methods, and safety. When a specimen-specific safety warning appears, the public-health source listed here directly supports that precaution. They are not line-by-line citations for every other property on this entry, and natural specimens vary.

Editorial owner

GeoMiner

Last updated

2026-02-10T20:25:54.470219+00:00

Review status

Published; not independently peer-reviewed

• IMA–CNMNC List of Mineral Names — International Mineralogical Association. Official mineral-name, nomenclature, and classification records.
• Mineral ID Key — Mineralogical Society of America. Physical-property identification methods, repeat-testing guidance, and limitations.

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Common questions

What is Moonstone?

Feldspar gem variety displaying adularescence — a floating blue-white sheen caused by light scattering from alternating feldspar layers.

How can you identify Moonstone?

Compare several properties rather than relying on colour alone. This entry records colour: Colorless with blue adularescence; lustre: Vitreous to pearly; streak: White; Mohs hardness: 6-6.5; cleavage: Perfect in two directions; crystal system: Monoclinic; transparency: Transparent to translucent. Confirm an important identification with additional field tests or qualified laboratory work.

How does Moonstone form?

Forms when orthoclase and albite intergrow and then separate into alternating layers upon cooling.

Where is Moonstone commonly found?

Sri Lanka, India, Myanmar, Madagascar; found in syenites and pegmatites.

What is Moonstone commonly confused with?

Moonstone may be confused with Labradorite, Opal, Chalcedony. Compare multiple diagnostic properties because colour and surface appearance can overlap.