Velvet Opal Identification Guide
A practical field guide to recognizing Velvet Opal, a soft, milky common opal with a velvety sheen, and separating it from chalcedony and howlite.
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What Velvet Opal Looks Like
Velvet Opal is a variety of common opal (potch, no play-of-color) prized for a soft, satiny or "velvety" surface luster rather than fiery flashes. Expect:
- Color: milky white, cream, pale blue-grey, soft pink or lavender, often with a subtle glow.
- Luster: waxy to greasy, with a characteristic soft "velvet" sheen when polished.
- Transparency: translucent to nearly opaque; light passes a short way into the stone.
- Form: massive, nodular or vein-filling, never crystalline, since opal is amorphous (a mineraloid).
Step-by-Step Field Checklist
- Look for the glow, not the fire. Velvet Opal shows a gentle internal sheen, not spectral color flashes.
- Check the surface texture. A soft, almost matte-velvety reflection is the trademark.
- Feel the weight. Opal is light (SG ~2.0-2.2), noticeably lighter than quartz of the same size.
- Test hardness. It scratches glass but a quartz point will scratch it (Mohs ~5.5-6.5).
- Examine for conchoidal fracture on chips: curved, shell-like breaks with no cleavage.
Key Diagnostic Tests
- Mohs hardness: 5.5-6.5. Softer than quartz (7); a quartz point lightly scratches it.
- Streak: white.
- Cleavage/Fracture: none; conchoidal to uneven fracture.
- Density: low, ~2.0-2.2 g/cm3, feels light in the hand.
- Acid: no reaction to dilute HCl (distinguishes from carbonate look-alikes).
- UV: common opal may show weak green or white fluorescence.
Common Look-Alikes
- Chalcedony / blue chalcedony: harder (Mohs 7), denser, scratches glass more readily and is not scratched by quartz; usually a glassier luster.
- Howlite: chalky white with grey veining, much softer (Mohs 3.5), a knife marks it easily and it is porous.
- Magnesite / dyed stones: softer and react to acid (magnesite fizzes when powdered in warm acid).
- Opalite (man-made glass): shows a bright orange transmitted glow plus blue reflected sheen and gas bubbles under magnification; Velvet Opal is natural and bubble-free.
Where It Is Found
Velvet Opal and other common opals form in silica-rich volcanic and sedimentary settings, notably Peru, Mexico, Australia, Turkey and the western United States, typically filling cavities and seams in altered rock.
Frequently asked questions
How can you tell if it's real Velvet Opal?
Confirm it is opal: low density (feels light), Mohs ~5.5-6.5, conchoidal fracture, no cleavage, and no acid reaction. Velvet Opal specifically shows a soft satiny sheen rather than the spectral play-of-color of precious opal.
What does Velvet Opal look like?
It is a translucent, milky white, cream, pale blue or pink common opal with a waxy-to-velvety surface luster and a gentle internal glow, but no rainbow flashes.
Velvet Opal vs chalcedony, how do I tell them apart?
Chalcedony is harder (Mohs 7) and denser, scratches glass easily and resists a quartz point, while Velvet Opal is softer, lighter, and shows a softer velvety sheen.
Does Velvet Opal show play-of-color?
No. It is a common opal, so it has a soft sheen and glow rather than the flashing rainbow fire seen in precious or black opal.