Piretite is a very rare hydrated calcium selenite mineral found in the oxidation zones of uranium-selenium deposits. It typically forms small, transparent, yellow tabular crystals that are highly sought after by systematic mineral collectors.
Is this piretite?
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 piretite with a known reference. Piretite 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. Piretite leaves a light yellow streak.
- 3Read the lusterHold the specimen under a strong light. Piretite typically shows a adamantine luster.
- 4Match the color rangeCompare against the expected color range: yellow, yellow-orange.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: tabular crystals.
Often confused with
Piretite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Piretite leaves light yellow, Anglesite leaves white.
How to tell apart: Cerussite is the harder of the two (Mohs 3-3.5 vs. 2); streak differs — Piretite leaves light yellow, Cerussite leaves white.
Often found alongside piretite
Minerals reported to co-occur with piretite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca₃(SeO₃)₃·(H₂O)
- Mohs hardness
- 2
- Density
- 4.2 g/cm³
- Colors
- Streak
- Light Yellow
- Luster
- Adamantine
- Transparency
- Transparent
- Crystal system
- Orthorhombic
- Crystal habit
- Tabular Crystals
- Cleavage
- Perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Oxidized Zone of Uranium-selenium Deposits
- Typical price
- $100-500 per specimen
Where rockhounds find piretite
Classic worldwide localities
- Shinkolobwe mine, Democratic Republic of the Congo
Field-hunting tip
Look in oxidized zone of uranium-selenium deposits country — that is the host setting where piretite typically forms. If you start seeing derriksite, guilleminite, marthozite in float, you are in the right ground. Field specimens usually show a tabular crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find piretite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
