Legrandite is a highly sought-after secondary mineral known for its vibrant yellow color and elongated prismatic crystal form. It is most famous for its occurrences at the Ojuela Mine in Mexico, where it forms stunning, sharp radiating sprays of crystals.
Is this legrandite?
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 legrandite with a known reference. Legrandite sits at Mohs 4.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Legrandite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Legrandite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: yellow, yellowish-orange.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic crystals, radial sprays.
Often confused with
Legrandite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside legrandite
Minerals reported to co-occur with legrandite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Zn₂(AsO₄)(OH)·H₂O
- Mohs hardness
- 4.5
- Density
- 4.0 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic Crystals, Radial Sprays
- Cleavage
- Perfect On {110}
- Fluorescence
- Bright Yellow Under SW UV
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Oxidized Hydrothermal Lead-zinc Deposits
- Typical price
- $50-500 thumbnail, $500-3000 cabinet
Where rockhounds find legrandite
Classic worldwide localities
- Ojuela Mine, Mapimi, Mexico
Field-hunting tip
Look in oxidized hydrothermal lead-zinc deposits country — that is the host setting where legrandite typically forms. If you start seeing adamite, smithsonite, hemimorphite in float, you are in the right ground. Field specimens usually show a prismatic crystals, radial sprays habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find legrandite on the map
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