Hidalgoite is a rare member of the beudantite group, typically found as an oxidation product of primary lead ores. Collectors look for its small, often pale-colored tabular crystals which occur in weathered mineral zones alongside other lead arsenates.
Is this hidalgoite?
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 hidalgoite with a known reference. Hidalgoite 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. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: dull in aggregates.
- 4Match the color rangeCompare against the expected color range: white, gray white, light green, light gray.
- 5Look at form & habitCrystal system: trigonal. Typical habit: tabular crystals, crusts, massive.
Often confused with
Hidalgoite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Hidalgoite leaves white, Beudantite leaves grayish yellow to green; luster reads dull in aggregates on Hidalgoite and vitreous, resinous, may be frosted on Beudantite.
How to tell apart: Streak differs, so Hidalgoite leaves white, Corkite leaves yellow; luster reads dull in aggregates on Hidalgoite and vitreous to resinous on Corkite.
How to tell apart: Luster reads dull in aggregates on Hidalgoite and vitreous to adamantine on Svanbergite.
Often found alongside hidalgoite
Minerals reported to co-occur with hidalgoite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- PbAl₃(AsO₄)(SO₄)(OH)₆
- Mohs hardness
- 4.5
- Density
- 3.71-3.96 g/cm³
- Streak
- White
- Luster
- Dull in aggregates
- Transparency
- Translucent
- Crystal system
- Trigonal
- Crystal habit
- Tabular crystals, crusts, massive
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A rare secondary mineral of the oxide zone of polymetallic sulfide deposits
Where rockhounds find hidalgoite
Classic worldwide localities
- Gold Hill mine, Tooele Co., Utah, USA
- Mohawk mine, Clark Mountains, San Bernardino Co., California, USA
- Tombstone, Cochise Co., and in the Silver Crown mine, Yavapai Co., Arizona, USA
- San Pascual mine, nine km northwest of Zimapán, Hidalgo, Mexico
- Cap Garonne mine, near le Pradet, Var, France
- Falotta mine, Oberhalbstein, Graubünden, Switzerland
Field-hunting tip
Where it forms: A rare secondary mineral of the oxide zone of polymetallic sulfide deposits. If you start seeing beudantite, tourmaline, limonite in float, you are in the right ground. Typical habit: tabular crystals, crusts, massive. Train your eye for that shape before scanning the outcrop.
Common questions
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Find hidalgoite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
