Peprossiite-(Ce) is an extremely rare borate mineral found in specific carbonatite complexes. It typically presents as small, pale yellow to lemon-yellow, platy, or hexagonal crystals and is highly valued by serious micromount collectors.
Is this peprossiite-(ce)?
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 peprossiite-(ce) with a known reference. Peprossiite-(Ce) 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: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: brownish yellow, light yellow, lemon.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: platy crystals, granular.
Often confused with
Peprossiite-(Ce) vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside peprossiite-(ce)
Minerals reported to co-occur with peprossiite-(ce). Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CeAl₂(B₃.₆₇Si₀.₃₃)O₁₀.₆₇
- Mohs hardness
- ~2
- Density
- 3.45 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent to translucent
- Crystal system
- Hexagonal
- Crystal habit
- Platy crystals, granular
- Cleavage
- Perfect on {0001}; distinct on {1120}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A very rare mineral, formed in cavities in sanidine ejecta by circulation of pneumatolytic to hydrothermal fluids, probably above 350°C (Monte Cavalluccio, Italy)
Where rockhounds find peprossiite-(ce)
Classic worldwide localities
- Monte Cavalluccio, Campagnano, Lazio, Italy
- Cura di Vetralla and Capranico Vicano, Viterbo, Italy
Field-hunting tip
Where it forms: A very rare mineral, formed in cavities in sanidine ejecta by circulation of pneumatolytic to hydrothermal fluids, probably above 350°C (Monte Cavalluccio, Italy). If you start seeing sanidine, aegirine–augite, hellandite in float, you are in the right ground. Typical habit: platy crystals, granular. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify peprossiite-(ce)?+
Where is peprossiite-(ce) found?+
What rocks look like peprossiite-(ce)?+
What minerals are found with peprossiite-(ce)?+
What kind of rock does peprossiite-(ce) form in?+
What is peprossiite-(ce) used for?+
Find peprossiite-(ce) on the map
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