Identification guide · Semi-Precious Stones
How to Identify Moonstone
Moonstone is usually white, gray, and peach with a vitreous luster and is translucent. It has a Mohs hardness of 6. It is about as hard as window glass: a knife barely marks it, while a steel file (Mohs 6.5) will. Its streak is white. It is most often confused with Opal, Labradorite, and Feldspar; the tests below separate them.
Moonstone identification checklist
| Color | White, Gray, Peach, Blue sheen | Look at a clean, dry surface in daylight. Color zoning, banding or spots are as diagnostic as the hue. |
|---|---|---|
| Luster | Vitreous | Fresh surfaces shine like glass; a dull surface usually means weathering, so chip or wet a corner. |
| Transparency | Translucent | Hold a thin edge up to a bright light and note whether light passes through. |
| Mohs hardness | 6 | It is about as hard as window glass: a knife barely marks it, while a steel file (Mohs 6.5) will. |
| Streak | White | Drag a corner across unglazed porcelain (the back of a bathroom tile) and check the powder color. |
| Cleavage | Perfect | |
| Fracture | Uneven | |
| Specific gravity | 2.6 | Ordinary rock-like heft (specific gravity about 2.6), similar to quartz. |
| Crystal system | Monoclinic |
Moonstone look-alikes and how to tell them apart
Both sit near Mohs 6, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Moonstone vs Opal →
Both sit near Mohs 6, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Moonstone vs Labradorite →
Both sit near Mohs 6, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Moonstone vs Feldspar →
Quartz is harder (Mohs 7) than Moonstone (Mohs 6), so Quartz will scratch Moonstone and not the other way round. It is about as hard as window glass: a knife barely marks it, while a steel file (Mohs 6.5) will.
Is my Moonstone real?
- Hardness: real Moonstone sits at Mohs 6. Glass imitations are about 5.5, so use a steel file and a known reference mineral rather than glass alone.
- Bubbles: round gas bubbles under a 10x loupe mean glass or resin, never a natural stone.
- Color: dyed material concentrates color in cracks and pores; look for pigment collecting at the edges of fractures.
- Temperature: natural crystals feel cool and take longer to warm in your hand than plastic or resin.
Field tips
- Check whether the specimen's color and texture match typical Moonstone examples.
- Use hardness, streak, luster, grain size, and locality together; no single trait is enough for every specimen.
Moonstone identification FAQ
How can you tell if a rock is Moonstone?
Check the color (white, gray, peach, and blue sheen), the vitreous luster, a Mohs hardness of 6 and a white streak. Photographing it with the StoneSnap app gives a match in seconds.
What is the hardness of Moonstone?
Moonstone has a Mohs hardness of 6. It is about as hard as window glass: a knife barely marks it, while a steel file (Mohs 6.5) will.
What is the difference between Moonstone and Opal?
Moonstone (Mohs 6, vitreous luster) and Opal (Mohs 5.5, vitreous luster) look alike, but hardness, streak and heft usually separate them. See the full Moonstone vs Opal comparison for a side-by-side table.
How do I know if my Moonstone is real?
Real Moonstone matches the hardness listed above, shows no round gas bubbles under magnification, and does not concentrate dye in cracks. Glass and resin fakes fail at least one of those checks.
Is Moonstone worth anything?
Entry-level Moonstone specimens sell for around $10, typical collector pieces about $50, and premium examples $500 or more depending on size, quality and locality.
What color is Moonstone?
Moonstone is most often white, gray, peach, and blue sheen. Color varies with impurities and locality, so confirm with hardness and luster rather than color alone.
