Tunisite is an exceptionally rare hydrous carbonate mineral discovered in the Djebel Tir deposit of Algeria. It is most frequently found as small, pearly, platy crystals forming delicate rosettes within limestone cavities.
Is this tunisite?
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 tunisite with a known reference. Tunisite sits at Mohs 4.5, 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: pearly.
- 4Match the color rangeCompare against the expected color range: white, colorless.
- 5Look at form & habitCrystal system: tetragonal. Typical habit: platy crystals, rosettes.
Often confused with
Tunisite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Tunisite is noticeably harder (Mohs 4.5 vs. 3); luster reads pearly on Tunisite and vitreous; pearly on cleavages and {0001} on Calcite.
How to tell apart: Luster reads pearly on Tunisite and vitreous, resinous on fracture surfaces on Aragonite.
Often found alongside tunisite
Minerals reported to co-occur with tunisite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- NaCa₂Al₄(CO₃)₄(OH)₈Cl
- Mohs hardness
- 4.5
- Density
- 2.51 g/cm³
- Streak
- White
- Luster
- Pearly
- Transparency
- Semitransparent
- Crystal system
- Tetragonal
- Crystal habit
- Platy crystals, rosettes
- Cleavage
- Perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A very rare hydrothermal mineral, filling cavities in calcite (Sakiet Sidi Yousseff mine, Tunisia)
Where rockhounds find tunisite
Classic worldwide localities
- Sakiet Sidi Yousseff Pb–Zn mine, between Le Kef and Souk Ahras, Tunisia
- Slavyansk salt deposit, Dnieprovsk-Donets Basin, Ukraine
- Condorcet, Drôme, France
Field-hunting tip
Where it forms: A very rare hydrothermal mineral, filling cavities in calcite (Sakiet Sidi Yousseff mine, Tunisia). If you start seeing calcite, celestine, pyrite in float, you are in the right ground. Typical habit: platy crystals, rosettes. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify tunisite?+
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What rocks look like tunisite?+
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Find tunisite on the map
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