Mexican opal is a precious or common opal renowned for its vivid orange, red, and yellow body colors, often found within cavities of rhyolitic volcanic rock. Collectors should look for high-clarity specimens with intense fire (play-of-color) or brilliant saturation in 'jelly' varieties. It is uniquely sourced from the high-altitude volcanic regions of central and western Mexico.
Is this mexican 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 mexican opal with a known reference. Mexican 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. Mexican Opal leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Mexican Opal typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: orange, red, yellow, colorless.
- 5Look at form & habitCrystal system: amorphous. Typical habit: nodular, massive, botryoidal.
Often confused with
Mexican Opal vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside mexican opal
Minerals reported to co-occur with mexican 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
- Transparency
- Transparent
- Crystal system
- Amorphous
- Crystal habit
- Nodular, Massive, Botryoidal
- Cleavage
- None
- Rarity
- Uncommon
- Uses
- Gemstone, Collector, Jewelry
- Host rock
- Volcanic Rhyolite Flows
- Typical price
- $20-200 per gram for quality material
Where rockhounds find mexican opal
Classic worldwide localities
- Querétaro
- Jalisco
- Nayarit
- Hidalgo
Field-hunting tip
Look in volcanic rhyolite flows country — that is the host setting where mexican opal typically forms. If you start seeing rhyolite, chalcedony, quartz in float, you are in the right ground. Field specimens usually show a nodular, massive, botryoidal habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify mexican opal?+
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Find mexican opal on the map
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