Bleasdaleite is a rare copper phosphate mineral known primarily from its type locality in the Carrock Mine of the English Lake District. It typically appears as thin, dark brown platy crystals or as secondary crusts in weathered hydrothermal veins. Collectors prize it for its rarity and its association with other rare secondary copper minerals.
Is this bleasdaleite?
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 bleasdaleite with a known reference. Bleasdaleite sits at Mohs 2, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: pale brown.
- 3Read the lusterHold the specimen under a strong light. Luster: resinous.
- 4Match the color rangeCompare against the expected color range: dark brown, honey brown.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: encrustations, scaly.
Often confused with
Bleasdaleite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Paranatisite is the harder of the two (Mohs 5 vs. 2); streak differs, so Bleasdaleite leaves pale brown, Paranatisite leaves white; luster reads resinous on Bleasdaleite and vitreous to adamantine on Paranatisite.
How to tell apart: Turquoise is the harder of the two (Mohs 5-6 vs. 2); streak differs, so Bleasdaleite leaves pale brown, Turquoise leaves white to pale greenish blue; luster reads resinous on Bleasdaleite and vitreous in crystals; dull to waxy if massive on Turquoise.
How to tell apart: Pseudomalachite is the harder of the two (Mohs 4.5-5 vs. 2); luster reads resinous on Bleasdaleite and vitreous to resinous on Pseudomalachite.
Often found alongside bleasdaleite
Minerals reported to co-occur with bleasdaleite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca₂Cu₅(Bi,Cu)(PO₄)₄(H₂O,OH,Cl)₁₃
- Mohs hardness
- 2
- Density
- 2.77 g/cm³
- Colors
- Dark brownHoney brown
- Streak
- Pale brown
- Luster
- Resinous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Encrustations, scaly
- Cleavage
- Well developed on {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A secondary mineral from cavities in weathered uraniferous granitic pegmatite containing partly oxidized copper sulfide minerals
Where rockhounds find bleasdaleite
Classic worldwide localities
- Lake Boga, Swan Hill Rural City, Victoria, Australia
Field-hunting tip
Where it forms: A secondary mineral from cavities in weathered uraniferous granitic pegmatite containing partly oxidized copper sulfide minerals. If you start seeing chalcopyrite, arsenopyrite, liroconite in float, you are in the right ground. Typical habit: encrustations, scaly. Train your eye for that shape before scanning the outcrop.
Common questions
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Find bleasdaleite on the map
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