Crystal guide
How to Identify Moonstone
Feldspar (orthoclase/albite)
Moonstone is a feldspar gem (orthoclase/albite intergrowth) showing adularescence — a soft blue-white billow rolling across the surface. Identify it by pale body color, floating sheen that moves with tilt, Mohs 6–6.5, and feldspar cleavage beneath the glow.
About Moonstone
Moonstone is a feldspar gem (orthoclase/albite intergrowth) showing adularescence — a soft blue-white billow rolling across the surface. Identify it by pale body color, floating sheen that moves with tilt, Mohs 6–6.5, and feldspar cleavage beneath the glow.
Moonstone is filed under crystals in the RockScan directory. Composition: Potassium/sodium aluminum silicate intergrowth. It forms via pegmatites and metamorphic rocks. Typical occurrence: Sri Lanka, India, Myanmar, Madagascar. For the broader method, see how to identify rock types.
Moonstone properties
| Mohs hardness | 6–6.5 |
|---|---|
| Class | crystal |
| Scientific name | Feldspar (orthoclase/albite) |
| Color | Colorless to peach with blue adularescence |
| Luster | Vitreous |
| Crystal system / texture | Monoclinic |
| Composition | Potassium/sodium aluminum silicate intergrowth |
| Formation | Pegmatites and metamorphic rocks |
| Occurrence | Sri Lanka, India, Myanmar, Madagascar |
How to identify Moonstone
- Billowy blue-white sheen rolling across a pale feldspar body.
- Mohs 6–6.5; shows feldspar cleavage, not glass bubbles.
- Sheen moves with tilt (adularescence), unlike opal's fixed patches.
Lookalikes to rule out
- Labradorite: Labradorite flashes strong spectral colors on a gray base; moonstone glows with a soft blue billow on a pale body.
- Opal: Opal shows patchy play-of-color with no cleavage planes; moonstone's sheen rolls across feldspar layers.
- Opalite glass: Opalite glass looks uniformly milky with molded shapes and possible bubbles; moonstone shows layered adularescence and feldspar cleavage.
Photo tips for Moonstone ID
- Tilt the stone under a single light source — adularescence only appears at the rolling angle.
- Shoot cabochons against a dark background so the blue billow stands out.
- Capture feldspar cleavage and layered structure in side views to rule out glass.
Snap one specimen in natural light, then open the result in the online studio or the rock identifier app.
Moonstone FAQ
How do you identify moonstone?
Tilt it under one light — a soft blue billow rolls across pale feldspar. Labradorite flashes rainbow on gray; glass looks uniformly milky.
Moonstone vs opal?
Opal's play-of-color sits in fixed patches with no cleavage; moonstone's glow rolls across feldspar layers.
What is rainbow moonstone?
Trade name for white labradorite with multicolor sheen — true moonstone is orthoclase with blue adularescence.
How to identify moonstone
Milky glass imitations flood the moonstone market, so buyers search the real tell. The rolling sheen plus feldspar structure gives it away:
- Rolling billow: blue-white sheen glides across the dome as you tilt — glass glows statically.
- Pale body: colorless to peach base; strong gray body with spectral flash is labradorite.
- Feldspar structure: layered intergrowth and cleavage planes visible in side views.
- No bubbles: a loupe shows layering, never molded seams or round gas bubbles.
- Photo confirm: video or tilt-series stills on dark ground, then RockScan against labradorite and opal.
Moonstone vs labradorite vs opal vs opalite glass
- Labradorite: bold rainbow flash on gray feldspar; moonstone is a soft blue billow on pale stone.
- Opal: fixed play-of-color patches in amorphous silica with no cleavage.
- Opalite glass: uniform milky glow with bubbles or mold lines; no feldspar layering.
Photo tips for adularescence
Single-point light on a dark background makes the billow roll on camera; shoot a tilt series, not one still. Compare labradorite, opal, and clear quartz guides, then confirm in the online studio or rock identifier app.
Related crystals to compare
Browse all: rocks · minerals · crystals · directory · what rock is this · rock vs mineral vs crystal. Confirm with the online studio or rock identifier app.