Pseudoboleite is a rare lead-copper halide typically found as deep blue, pseudocubic crystals. It is most famously associated with the Boleo district in Mexico, where it forms in oxidized hydrothermal veins alongside other secondary copper minerals.
Is this pseudoboleite?
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 pseudoboleite with a known reference. Pseudoboleite 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. Pseudoboleite leaves a blue streak.
- 3Read the lusterHold the specimen under a strong light. Pseudoboleite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: deep blue, azure.
- 5Look at form & habitCrystal system: tetragonal. Typical habit: pseudocubic crystals, tabular, granular.
Often confused with
Pseudoboleite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Pseudoboleite leaves blue, Boleite leaves light blue.
How to tell apart: Streak differs — Pseudoboleite leaves blue, Cumengeite leaves pale blue; luster reads vitreous on Pseudoboleite and vitreous to adamantine on Cumengeite.
How to tell apart: Streak differs — Pseudoboleite leaves blue, Diaboleite leaves pale blue.
Often found alongside pseudoboleite
Minerals reported to co-occur with pseudoboleite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Pb₃₁Cu₂₄Cl₆₂(OH)₄₈
- Mohs hardness
- 2.5-3
- Density
- 5.0-5.1 g/cm³
- Streak
- Blue
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Tetragonal
- Crystal habit
- Pseudocubic Crystals, Tabular, Granular
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Oxidized Zones of Lead-copper Ore Deposits
- Typical price
- $50-500 thumbnail, $200-1500 cabinet
Where rockhounds find pseudoboleite
Classic worldwide localities
- Boleo, Baja California, Mexico
- Commander Islands, Russia
- Laurion, Greece
Field-hunting tip
Look in oxidized zones of lead-copper ore deposits country — that is the host setting where pseudoboleite typically forms. If you start seeing boleite, cumengeite, atacamite in float, you are in the right ground. Field specimens usually show a pseudocubic crystals, tabular, granular habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find pseudoboleite on the map
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