Liskeardite is a rare secondary mineral found in the oxidized zones of arsenic-rich ore deposits. It typically presents as delicate, pearly-white or pale green platy crusts and radial aggregates, often requiring magnification for clear identification of its crystal habit.
Is this liskeardite?
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 liskeardite with a known reference. Liskeardite sits at Mohs 1-2, 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: pearly.
- 4Match the color rangeCompare against the expected color range: bluish, bluish white, brownish white, greenish, greenish white.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: encrustations.
Often confused with
Liskeardite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Liskeardite leaves white, Pharmacosiderite leaves yellowish green; luster reads pearly on Liskeardite and adamantine to greasy on Pharmacosiderite.
How to tell apart: Scorodite is the harder of the two (Mohs 3.5-4 vs. 1-2); streak differs, so Liskeardite leaves white, Scorodite leaves greenish white; luster reads pearly on Liskeardite and vitreous to subadamantine, subresinous on Scorodite.
Often found alongside liskeardite
Minerals reported to co-occur with liskeardite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Al,Fe)₃₂(AsO₄)₁₈(OH)₄₂(H₂O)₂₂·52H₂O
- Mohs hardness
- 1-2
- Density
- 3.1 g/cm³
- Streak
- White
- Luster
- Pearly
- Transparency
- Semitransparent
- Crystal system
- Orthorhombic
- Crystal habit
- Encrustations
- Cleavage
- Good
- Rarity
- Rare
- Uses
- Collector
- Host rock
- An oxidation product of arsenic-bearing sulfides
Where rockhounds find liskeardite
Classic worldwide localities
- Marke Valley mine, Liskeard, and at the Penberthy Croft mine, St. Hilary, Cornwall, England
- Cap Garonne mine, near le Pradet, Var, France
- Tannenberg tin mine, Mühlleithen, Saxony, Germany
Field-hunting tip
Where it forms: An oxidation product of arsenic-bearing sulfides. If you start seeing scorodite, arsenopyrite, chalcopyrite in float, you are in the right ground. Typical habit: encrustations. Train your eye for that shape before scanning the outcrop.
Common questions
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Find liskeardite on the map
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