Piergorite-(Ce) is a rare silicate mineral found in alkaline pegmatite environments. It typically forms small prismatic crystals and is recognized by its distinct brown to yellow coloration and characteristic association with rare earth element minerals.

Hardness

5.5

Mohs

Luster

Vitreous

Streak

White

Transparency

Translucent

mineralrareGadolinite Group family

Piergorite-(Ce)

Hardness: 5.5
Luster: Vitreous
Streak: White
Transparency: Translucent

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Is this piergorite-(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 piergorite-(ce) with a known reference. Piergorite-(Ce) sits at Mohs 5.5 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Piergorite-(Ce) leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Piergorite-(Ce) typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: yellow, brown, dark brown.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: prismatic crystals.

Often confused with

Piergorite-(Ce) vs. its common look-alikes — and how to tell them apart in the field.

mineral

Gadolinite-(Y)

Mohs 6.5-7

How to tell apart: Gadolinite-(Y) is the harder of the two (Mohs 6.5-7 vs. 5.5).

Compare →

Often found alongside piergorite-(ce)

Minerals reported to co-occur with piergorite-(ce). Spotting these in float or country rock is a strong cue you are in the right ground.

All properties

Chemical formula: CaCe₄(Si₂O₇)(SiO₄)O(OH)₃
Mohs hardness: 5.5
Density: 4.15 g/cm³
Colors: Yellow Brown Dark Brown
Streak: White
Luster: Vitreous
Transparency: Translucent
Crystal system: Monoclinic
Crystal habit: Prismatic Crystals
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Alkaline Pegmatites
Typical price: $50-300 per specimen

Where rockhounds find piergorite-(ce)

Classic worldwide localities

Kola Peninsula, Russia
Srednyaya Varaka, Russia

Field-hunting tip

Look in alkaline pegmatites country — that is the host setting where piergorite-(ce) typically forms. If you start seeing apatite, quartz, titanite in float, you are in the right ground. Field specimens usually show a prismatic crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify piergorite-(ce)?+

Mohs hardness is 5.5. It typically shows a vitreous luster. The streak is white. Common colors include yellow, brown, dark brown.

Where is piergorite-(ce) found?+

Notable localities include Kola Peninsula, Russia; Srednyaya Varaka, Russia.

How much is piergorite-(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.

Is piergorite-(ce) safe to handle?+

This mineral is radioactive. Contains minor amounts of thorium; standard mineral handling protocols apply including washing hands after handling and avoiding dust inhalation. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like piergorite-(ce)?+

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

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

Piergorite-(Ce) commonly co-occurs with Apatite, Quartz, Titanite, Microcline. Spotting any of these in float or country rock is a useful trip signal.

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

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

What is piergorite-(ce) used for?+

Piergorite-(Ce) is used in collector.

Find piergorite-(ce) on the map

RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.