Opalite is a trade name for a type of common, non-precious opal that typically displays a translucent, milky blue or white appearance. It is often confused with man-made opalized glass, but natural opalite is a volcanic mineral formed from silica-rich fluids. It is prized by lapidary artists for its smooth, polished finish and internal glow.
Is this opalite?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch opalite with a known reference. Opalite sits at Mohs 5.5-6.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Opalite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Opalite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, blue, milky.
- 5Look at form & habitCrystal system: amorphous. Typical habit: massive.
Often confused with
Opalite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside opalite
Minerals reported to co-occur with opalite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- SiO₂·nH₂O
- Mohs hardness
- 5.5-6.5
- Density
- 2.0-2.2 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Amorphous
- Crystal habit
- Massive
- Cleavage
- None
- Fluorescence
- Often Exhibits Strong Sky-blue or Milky Fluorescence Under UV Light
- Rarity
- Common
- Uses
- Lapidary, Decorative, Collector
- Host rock
- Volcanic Ash Deposits
- Typical price
- $5-30 for small cabochons or rough pieces
Where rockhounds find opalite
6 mapped spotsClassic worldwide localities
- United States
- Mexico
- Peru
Field-hunting tip
Look in volcanic ash deposits country, the host setting where opalite typically forms. If you start seeing quartz, chalcedony, montmorillonite in float, you are in the right ground. Field specimens usually show a massive habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Nevada, California, Georgia. Start trip planning there.
Common questions
How do you identify opalite?+
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Can I find opalite in the United States?+
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Find opalite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
