Diaboleite is a striking rare lead-copper halide mineral typically found as deep blue square, tabular crystals. It is best known by collectors for its association with lead-ore oxidation zones, particularly in the historic mines of the Mendip Hills in England.
Is this diaboleite?
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 diaboleite with a known reference. Diaboleite sits at Mohs 2.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: pale blue.
- 3Read the lusterHold the specimen under a strong light. Luster: adamantine, pearly on cleavages.
- 4Match the color rangeCompare against the expected color range: dark blue, bright sky blue.
- 5Look at form & habitCrystal system: tetragonal. Typical habit: encrustations, euhedral crystals, granular.
Often confused with
Diaboleite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Diaboleite leaves pale blue, Boleite leaves blue, with greenish tint; luster reads adamantine, pearly on cleavages on Diaboleite and weakly vitreous; pearly on cleavage surfaces on Boleite.
How to tell apart: Streak differs, so Diaboleite leaves pale blue, Cumengeite leaves sky-blue; luster reads adamantine, pearly on cleavages on Diaboleite and weakly vitreous to adamantine on Cumengeite.
How to tell apart: Streak differs, so Diaboleite leaves pale blue, Pseudoboleite leaves light green; luster reads adamantine, pearly on cleavages on Diaboleite and pearly on cleavages on Pseudoboleite.
Often found alongside diaboleite
Minerals reported to co-occur with diaboleite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Pb₂CuCl₂(OH)₄
- Mohs hardness
- 2.5
- Density
- 5.48-6.41 g/cm³
- Colors
- Dark blueBright sky blue
- Streak
- Pale blue
- Luster
- Adamantine, pearly on cleavages
- Transparency
- Transparent to translucent
- Crystal system
- Tetragonal
- Crystal habit
- Encrustations, euhedral crystals, granular
- Cleavage
- {001}, perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In oxidized manganese ores (Mendip Hills, England); a secondary mineral in deeply oxidized Pb-Cu ores (Tiger, Arizona, USA); in slag exposed to seawater
Where rockhounds find diaboleite
Classic worldwide localities
- Mammoth-St. Anthony mine, Tiger, Pinal Co., and from the Rowley mine, Maricopa Co., Arizona, USA
- Higher Pitts Farm, Mendip Hills, and the Merehead quarry, near Shepton Mallet, Somerset, England
- Padstow Consols, Padstow, Cornwall, England
- Christian-Levin mine, near Essen, North Rhine-Westphalia, and from Richelsdorf, Hesse, in slag, Germany
- Baratti Beach, Tuscany, Italy, in slag
- Laurium, Greece, in slag
Field-hunting tip
Where it forms: In oxidized manganese ores (Mendip Hills, England); a secondary mineral in deeply oxidized Pb-Cu ores (Tiger, Arizona, USA); in slag exposed to seawater. If you start seeing chloroxiphite, hydrocerussite, mendipite in float, you are in the right ground. Typical habit: encrustations, euhedral crystals, granular. Train your eye for that shape before scanning the outcrop.
Common questions
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Find diaboleite on the map
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