Peprossiite-(Ce) is an extremely rare borate mineral found in specific carbonatite complexes. It typically presents as small, colorless, platy, or hexagonal crystals and is highly valued by serious micromount collectors.

Hardness

3.5

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrare

Peprossiite-(Ce)

Hardness: 3.5
Luster: Vitreous
Streak: White
Transparency: Transparent

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Is this peprossiite-(ce)?

5-step field check

Run through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.

1
Test the hardness
Try to scratch peprossiite-(ce) with a known reference. Peprossiite-(Ce) sits at Mohs 3.5 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Peprossiite-(Ce) leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Peprossiite-(Ce) typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: colorless, white.
5
Look at form & habit
Crystal 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.

mineral

Huntite

Mohs 1-2

How to tell apart: Peprossiite-(Ce) is noticeably harder (Mohs 3.5 vs. 1-2); luster reads vitreous on Peprossiite-(Ce) and dull on Huntite.

Compare →

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: LaAl₃B₄O₁₂
Mohs hardness: 3.5
Density: 4.15 g/cm³
Colors: Colorless White
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Hexagonal
Crystal habit: Platy Crystals, Granular
Cleavage: Perfect
Rarity: Rare
Uses: Collector
Host rock: Carbonatites
Typical price: $50-300 per specimen

Where rockhounds find peprossiite-(ce)

Classic worldwide localities

Siilinjarvi carbonatite complex, Finland

Field-hunting tip

Look in carbonatites country — that is the host setting where peprossiite-(ce) typically forms. If you start seeing phlogopite, apatite, calcite in float, you are in the right ground. Field specimens usually show a platy crystals, granular habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify peprossiite-(ce)?+

Mohs hardness is 3.5. It typically shows a vitreous luster. The streak is white. Common colors include colorless, white.

Where is peprossiite-(ce) found?+

Notable localities include Siilinjarvi carbonatite complex, Finland.

How much is peprossiite-(ce) worth?+

Typical asking prices fall in the range of $50-300 per specimen. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like peprossiite-(ce)?+

Peprossiite-(Ce) is most often confused with Huntite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with peprossiite-(ce)?+

Peprossiite-(Ce) commonly co-occurs with Phlogopite, Apatite, Calcite, Dolomite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does peprossiite-(ce) form in?+

Peprossiite-(Ce) typically forms in carbonatites. Working float back to the host body is the standard way to chase a fresh occurrence.

What is peprossiite-(ce) used for?+

Peprossiite-(Ce) is used in collector.

Find peprossiite-(ce) on the map

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