Rollandite is an extremely rare arsenate mineral that typically forms as delicate, violet-pink bladed crystals. It is primarily found in oxidized zones of arsenic-rich base metal deposits and is highly sought after by advanced collectors for its distinct color and scarcity.
Is this rollandite?
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 rollandite with a known reference. Rollandite 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. Rollandite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Rollandite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: pink, violet.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: bladed to acicular crystals.
Often confused with
Rollandite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Cornubite is the harder of the two (Mohs 3-4 vs. 2); streak differs — Rollandite leaves white, Cornubite leaves pale green.
How to tell apart: Olivenite is the harder of the two (Mohs 3 vs. 2); streak differs — Rollandite leaves white, Olivenite leaves olive-green; luster reads vitreous on Rollandite and adamantine on Olivenite.
Often found alongside rollandite
Minerals reported to co-occur with rollandite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Cu₃(AsO₄)₂·4H₂O
- Mohs hardness
- 2
- Density
- 3.37 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Bladed to Acicular Crystals
- Cleavage
- Perfect On {010}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Vein Deposits in Sandstone or Metamorphic Rocks
- Typical price
- $100-500+ for high-quality micro specimens
Where rockhounds find rollandite
Classic worldwide localities
- Cap Garonne, France
- Schneeberg, Germany
Field-hunting tip
Look in hydrothermal vein deposits in sandstone or metamorphic rocks country — that is the host setting where rollandite typically forms. If you start seeing tennantite, olivenite, cornubite in float, you are in the right ground. Field specimens usually show a bladed to acicular crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find rollandite on the map
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