Ilímaussite-(Ce) is a rare silicate mineral found almost exclusively in the alkaline rocks of the Ilimaussaq complex in Greenland. It typically occurs as small, pale yellow to brownish platy crystals embedded in pegmatite matrices. Due to its radioactive content, it is highly sought after by systematic mineral collectors.

Hardness

3.5

Mohs

Luster

Vitreous

Streak

White

Transparency

Translucent

mineralrare

Ilímaussite-(Ce)

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

Is this ilímaussite-(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 ilímaussite-(ce) with a known reference. Ilímaussite-(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. Ilímaussite-(Ce) leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Ilímaussite-(Ce) typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: yellow, brown, pale yellow.
5
Look at form & habit
Crystal system: hexagonal. Typical habit: platy crystals.

Often confused with

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

mineral

Steenstrupine-(Ce)

Mohs 4

How to tell apart: Streak differs — Ilímaussite-(Ce) leaves white, Steenstrupine-(Ce) leaves yellowish brown.

How to tell apart: Eudialyte is the harder of the two (Mohs 5-6 vs. 3.5).

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Often found alongside ilímaussite-(ce)

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

All properties

Chemical formula: Na₄Ba₂CeFeNb₂Si₈O₂₈·5H₂O
Mohs hardness: 3.5
Density: 3.5 g/cm³
Colors: Yellow Brown Pale Yellow
Streak: White
Luster: Vitreous
Transparency: Translucent
Crystal system: Hexagonal
Crystal habit: Platy Crystals
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Nepheline Syenite Pegmatites
Typical price: $50-300 per specimen

Where rockhounds find ilímaussite-(ce)

Classic worldwide localities

Ilimaussaq complex, Greenland

Field-hunting tip

Look in nepheline syenite pegmatites country — that is the host setting where ilímaussite-(ce) typically forms. If you start seeing steenstrupine-(ce), eudialyte, sodalite in float, you are in the right ground. Field specimens usually show a platy crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify ilímaussite-(ce)?+

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

Where is ilímaussite-(ce) found?+

Notable localities include Ilimaussaq complex, Greenland.

How much is ilímaussite-(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 ilímaussite-(ce) safe to handle?+

This mineral is radioactive. Contains rare earth elements and may be weakly radioactive; handle with care and wash hands after contact. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like ilímaussite-(ce)?+

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

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

Ilímaussite-(Ce) commonly co-occurs with Steenstrupine-(Ce), Eudialyte, Sodalite, Microcline, Aegirine. Spotting any of these in float or country rock is a useful trip signal.

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

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

What is ilímaussite-(ce) used for?+

Ilímaussite-(Ce) is used in collector.

Find ilímaussite-(ce) on the map

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