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, 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
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Find mexican opal on the map
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