Mereheadite is an extremely rare lead oxychloride mineral discovered in the Mendip Hills of England. It typically forms thin, colorless to pale yellow platy crystals or crusts within cavities in manganese-rich host rocks, often associated with other rare lead species.
Is this mereheadite?
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 mereheadite with a known reference. Mereheadite sits at Mohs 3.5, 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: vitreous to resinous.
- 4Match the color rangeCompare against the expected color range: pale yellow, reddish orange.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: granular.
Often confused with
Mereheadite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Mereheadite is noticeably harder (Mohs 3.5 vs. 2.5); streak differs, so Mereheadite leaves white, Chloroxiphite leaves pale yellowish green; luster reads vitreous to resinous on Mereheadite and resinous to adamantine on Chloroxiphite.
How to tell apart: Luster reads vitreous to resinous on Mereheadite and subadamantine on Paralaurionite.
Often found alongside mereheadite
Minerals reported to co-occur with mereheadite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Pb₄₇O₂₄(OH)₁₃Cl₂₅(BO₃)₂(CO₃)
- Mohs hardness
- 3.5
- Density
- 7.12 g/cm³
- Streak
- White
- Luster
- Vitreous to resinous
- Transparency
- Translucent to transparent
- Crystal system
- Monoclinic
- Crystal habit
- Granular
- Cleavage
- Perfect on {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In lenses and cavities in veins of manganese and iron minerals which cut dolomitic limestones
Where rockhounds find mereheadite
Classic worldwide localities
- Merehead Quarry (Torr Works), near Cranmore, Somerset, England
- Reported from the Clara mine, Oberwolfach, Wolfach, Black Forest, Baden-Württemberg, Germany
Field-hunting tip
Where it forms: In lenses and cavities in veins of manganese and iron minerals which cut dolomitic limestones. If you start seeing cerussite, blixite, mendipite in float, you are in the right ground. Typical habit: granular. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify mereheadite?+
Where is mereheadite found?+
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Find mereheadite on the map
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