Green Moonstone Identification Guide
A guide to identifying green moonstone by its adularescent sheen, feldspar cleavage, and hardness, and separating it from chalcedony and prehnite.
Read the full Green Moonstone encyclopedia entry →
What Green Moonstone Looks Like
Green moonstone is a feldspar (typically a potassium feldspar like orthoclase, or a sodium-rich plagioclase) that displays a soft greenish adularescence—a billowy blue-to-green sheen that floats below the surface and moves as the stone is tilted. The body color is pale green to grayish green, translucent to semi-transparent, with a smooth vitreous-to-pearly luster. The schiller comes from microscopic intergrowths of two feldspars.
Step-by-Step Field-ID Checklist
- Tilt under light: look for the floating blue-green glow (adularescence) that shifts position—this is the defining moonstone feature.
- Test hardness: moonstone scratches glass faintly but is itself scratched by quartz/topaz (Mohs ~6–6.5).
- Hunt for cleavage: broken pieces show two cleavage directions meeting near 90°.
- Check the streak: white.
- Look for internal "centipede" inclusions: moonstone often shows characteristic stress cracks.
Key Diagnostic Tests
- Mohs hardness: 6–6.5
- Streak: white
- Cleavage: two good cleavages at ~90° (feldspar hallmark)
- Specific gravity: ~2.55–2.63
- Optics: biaxial; adularescence rather than a single sharp reflection
- No acid reaction; non-magnetic
Common Look-Alikes and How to Tell Them Apart
- Chalcedony / green opal: Lack feldspar cleavage; chalcedony is harder (7) and opal shows a different (sometimes play-of-color) sheen. Moonstone's glow is internal and billowy.
- Prehnite: Has a more granular, sometimes botryoidal habit and a slightly oily green; harder to mistake once cleavage is found.
- Labradorite/green sunstone: Labradorite shows iridescent flashes (labradorescence) in distinct color patches, not the soft single blue-green float of moonstone.
- Amazonite: Opaque, bluer-green, with grid-like white streaking and no adularescence.
- Glass/opalite imitation: Even, milky glow without crystal cleavage; often has bubbles.
Where Green Moonstone Is Found
Moonstone-bearing feldspar comes from Sri Lanka, India, Madagascar, Myanmar, Tanzania, and the United States. Green-sheened material is reported particularly from India and Sri Lanka.
Frequently asked questions
How can you tell if it's real green moonstone?
Real green moonstone shows a floating blue-green adularescent sheen that moves as you tilt it, has a hardness of 6–6.5, two cleavage directions near 90 degrees, and a white streak.
What does green moonstone look like?
It is a pale green to grayish, translucent feldspar with a soft billowy blue-to-green glow drifting beneath a smooth, slightly pearly surface.
Green moonstone vs labradorite: how do I tell them apart?
Moonstone shows a single soft blue-green float (adularescence), while labradorite flashes distinct patches of iridescent color (labradorescence) in blues, greens, and golds.
Is green moonstone the same as opalite?
No. Opalite is usually man-made or treated glass with an even milky glow and gas bubbles, while green moonstone is a natural feldspar with cleavage and a directional adularescent sheen.
Green Moonstone identified by the community
Recent Green Moonstone specimens identified with Rock Identifier.
