Vauquelinite is a rare lead copper chromate phosphate that typically forms distinctive greenish crusts or botryoidal coatings. It is most commonly found in the oxidized zones of lead-bearing ore deposits where it is often associated with crocoite.
Is this vauquelinite?
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 vauquelinite with a known reference. Vauquelinite sits at Mohs 2.5-3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: greenish to brownish.
- 3Read the lusterHold the specimen under a strong light. Luster: adamantine to resinous.
- 4Match the color rangeCompare against the expected color range: green, brown, brownish green, brownish black, black.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: mammillary, reniform.
Often confused with
Vauquelinite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Vauquelinite leaves greenish to brownish, Phoenicochroite leaves brick-red to yellowish orange.
How to tell apart: Streak differs, so Vauquelinite leaves greenish to brownish, Crocoite leaves yellow-orange.
How to tell apart: Streak differs, so Vauquelinite leaves greenish to brownish, Mottramite leaves yellowish green; luster reads adamantine to resinous on Vauquelinite and greasy on Mottramite.
Often found alongside vauquelinite
Minerals reported to co-occur with vauquelinite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Pb₂Cu(CrO₄)(PO₄)OH
- Mohs hardness
- 2.5-3
- Density
- 6.16 g/cm³
- Streak
- Greenish to brownish
- Luster
- Adamantine to resinous
- Transparency
- Translucent to transparent in thin fragments
- Crystal system
- Monoclinic
- Crystal habit
- Mammillary, reniform
- Cleavage
- Indistinct
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A rare mineral in the oxidized zones of some hydrothermal base-metal deposits
Where rockhounds find vauquelinite
Classic worldwide localities
- A number of localities south and west of Wickenburg, Maricopa Co., as the Moon Anchor mine, the Rat Tail claim, the Potter-Kramer property, Vulture district, the Tonopah-Belmont mine, Osborne district, Arizona, USA
- Florence Lead-Silver mine, Tortilla Mountains, Pinal Co., Arizona, USA
- Vanadinite mine, Lost Basin district, Mohave Co., Arizona, USA
- Killie mine, Spruce Mountain district, Elko Co., in the Silver Coin mine, near Valmy, Iron Point district, Humboldt Co., Nevada, USA
- Tsvetnoi mine, Mt. Uspenskaya, Beresov district, near Yekaterinburg (Sverdlovsk), Middle Ural Mountains, Russia
- Öhrenstock, near Ilmenau, Thuringia, Germany
Field-hunting tip
Where it forms: A rare mineral in the oxidized zones of some hydrothermal base-metal deposits. If you start seeing crocoite, pyromorphite, mimetite in float, you are in the right ground. Typical habit: mammillary, reniform. Train your eye for that shape before scanning the outcrop.
Common questions
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Find vauquelinite on the map
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