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. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 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
Where rockhounds find mexican opal
Classic worldwide localities
- Querétaro
- Jalisco
- Nayarit
- Hidalgo
Field-hunting tip
Where it forms: volcanic rhyolite flows. If you start seeing rhyolite, chalcedony, quartz in float, you are in the right ground. Typical habit: nodular, massive, botryoidal. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify mexican opal?+
Where is mexican opal found?+
What rocks look like mexican opal?+
What minerals are found with mexican opal?+
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What is mexican opal used for?+
Find mexican opal on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
