Welo opal is a highly sought-after hydrophane opal known for its intense play-of-color and ability to absorb water. It typically occurs as nodules within volcanic tuff deposits in the Welo Province of Ethiopia and is valued for its remarkable transparency and vibrant flashes of neon color.
Is this welo opal?
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 welo opal with a known reference. Welo Opal 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. Welo Opal leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Welo Opal typically shows a vitreous to pearly luster.
- 4Match the color rangeCompare against the expected color range: white, yellow, orange, brown, colorless.
- 5Look at form & habitCrystal system: amorphous. Typical habit: nodular, massive, or vein fillings.
Often confused with
Welo Opal vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside welo opal
Minerals reported to co-occur with welo opal. 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
- 1.9-2.2 g/cm³
- Streak
- White
- Luster
- Vitreous to Pearly
- Transparency
- Transparent
- Crystal system
- Amorphous
- Crystal habit
- Nodular, Massive, Or Vein Fillings
- Cleavage
- None
- Fluorescence
- Often Exhibits Bright Green or Yellow Under UV Light
- Rarity
- Uncommon
- Uses
- Gemstone, Lapidary, Collector
- Host rock
- Volcanic Ash and Rhyolitic Tuffs
- Typical price
- $10-100 per carat depending on play-of-color quality
Where rockhounds find welo opal
Classic worldwide localities
- Welo Province, Ethiopia
Field-hunting tip
Look in volcanic ash and rhyolitic tuffs country — that is the host setting where welo opal typically forms. If you start seeing rhyolite, clay minerals, chalcedony in float, you are in the right ground. Field specimens usually show a nodular, massive, or vein fillings habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find welo opal on the map
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