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 — that is 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?+
Where is opalite found?+
Can I find opalite in the United States?+
How much is opalite worth?+
What rocks look like opalite?+
What minerals are found with opalite?+
What kind of rock does opalite form in?+
What is opalite used for?+
Find opalite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
