Cat's Eye Moonstone Identification Guide
Identify cat's eye moonstone by its adularescent feldspar body crossed by a chatoyant band, and tell it from quartz and chrysoberyl cat's eyes.
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What Cat's Eye Moonstone Looks Like
Cat's eye moonstone is moonstone (a feldspar, usually orthoclase/adularia) that combines its signature floating blue-white glow (adularescence) with a chatoyant cat's eye band. The result is a milky cabochon with both a soft inner shimmer and a sharp light line.
- Color: white to gray, sometimes peach or with a bluish sheen.
- Luster: vitreous to slightly pearly.
- Transparency: translucent, milky.
- Effect: adularescent billowy glow plus a single crossing light band.
Step-by-Step Field-ID Checklist
- Look for two effects: a floating blue/white sheen (adularescence) AND a sharp moving line (chatoyancy).
- Confirm feldspar cleavage: moonstone shows good cleavage planes — visible flat reflections.
- Hardness test: ~6–6.5; scratched by quartz, barely affects glass.
- Check the body: milky, slightly translucent, often with a faint blue glow rather than a vivid body color.
- Magnify for inclusions: fine parallel structures (and feldspar twinning planes) produce the effects.
Key Diagnostic Tests
- Mohs hardness: 6–6.5 (softer than quartz/chrysoberyl cat's eyes).
- Streak: white.
- Cleavage: two good cleavages — distinctive among cat's eye gems.
- Density: ~2.55–2.61 g/cm³ (low).
- Refractive index: ~1.52–1.53.
- Effect: adularescence + chatoyancy.
Common Look-Alikes
- Cat's eye quartz: harder (7), denser, no cleavage, and lacks the billowy adularescent glow.
- Chrysoberyl cat's eye: far harder (8.5), denser (~3.7), with a crisp eye and no adularescence.
- Cat's eye beryl: harder (7.5–8), no good cleavage, no adularescence.
- Milky glass/opalite: glass shows bubbles and a flat, even glow without true feldspar cleavage or twin planes.
Where Cat's Eye Moonstone Is Found
Moonstone forms in granites, pegmatites, and feldspar-rich rocks. The classic sources are Sri Lanka and India, with additional material from Myanmar and Madagascar. Cat's eye examples are selected from rough with the right parallel inclusions and cut en cabochon to show both optical effects.
Frequently asked questions
What is cat's eye moonstone?
It is moonstone feldspar that shows both adularescence (a floating blue-white glow) and chatoyancy (a single moving light band) when cut as a cabochon.
How can you tell cat's eye moonstone from chrysoberyl cat's eye?
Moonstone is much softer (6–6.5 vs 8.5), lighter (density ~2.57 vs ~3.7), has good feldspar cleavage, and shows a milky adularescent glow that chrysoberyl lacks.
What does cat's eye moonstone look like?
A milky white-to-gray translucent cabochon with a soft floating blue sheen crossed by a sharp band of light that moves as you tilt the stone.
Is cat's eye moonstone real moonstone?
Yes. It is genuine feldspar moonstone that happens to contain enough parallel inclusions to also produce a cat's eye, in addition to its normal adularescence.
Cat's Eye Moonstone identified by the community
Recent Cat's Eye Moonstone specimens identified with Rock Identifier.
