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. Diaboleite leaves a pale blue streak.
- 3Read the lusterHold the specimen under a strong light. Diaboleite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: deep blue, bright blue.
- 5Look at form & habitCrystal system: tetragonal. Typical habit: tabular crystals, thick square plates, crusts.
Often confused with
Diaboleite vs. its common look-alikes — and how to tell them apart in the field.

How to tell apart: Streak differs — Diaboleite leaves pale blue, Boleite leaves light blue.

How to tell apart: Luster reads vitreous on Diaboleite and vitreous to adamantine on Cumengeite.

How to tell apart: Streak differs — Diaboleite leaves pale blue, Pseudoboleite leaves blue.
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
- 5.4-5.5 g/cm³
- Colors
- Streak
- Pale Blue
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Tetragonal
- Crystal habit
- Tabular Crystals, Thick Square Plates, Crusts
- Cleavage
- Perfect On {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Oxidized Zones of Lead-copper Deposits
- Typical price
- $50-500 depending on crystal size and matrix quality
Where rockhounds find diaboleite
Classic worldwide localities
- Mendip Hills, England
- Mammoth-St. Anthony Mine, Arizona
- Laurion, Greece
- Sierra Gorda, Chile
Field-hunting tip
Look in oxidized zones of lead-copper deposits country — that is the host setting where diaboleite typically forms. If you start seeing cerussite, hydrocerussite, matlockite in float, you are in the right ground. Field specimens usually show a tabular crystals, thick square plates, crusts habit, so train your eye for that shape before scanning the outcrop.





