Dyrnæsite-(La) is an extremely rare silicate-carbonate mineral discovered in the alkaline rocks of the Ilimaussaq complex in Greenland. It typically occurs as small, delicate, brownish-yellow platy crystals associated with other rare earth minerals in pegmatite pockets. Due to its scarcity and restricted locality, it is primarily sought after by advanced systematic mineral collectors.

Hardness

4.5

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrareTundrite Group family

Dyrnaesite-(La)

Hardness: 4.5
Luster: Vitreous
Streak: White
Transparency: Transparent

No image

Is this dyrnaesite-(la)?

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 dyrnaesite-(la) with a known reference. Dyrnaesite-(La) sits at Mohs 4.5, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: white.
3
Read the luster
Hold the specimen under a strong light. Luster: vitreous.
4
Match the color range
Compare against the expected color range: pale yellowish green.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: thin platy crystals.

Often confused with

Dyrnaesite-(La) vs. its common look-alikes, and how to tell them apart in the field.

mineral

Tundrite-(Ce)

Mohs ~3

How to tell apart: Dyrnaesite-(La) is noticeably harder (Mohs 4.5 vs. ~3); streak differs, so Dyrnaesite-(La) leaves white, Tundrite-(Ce) leaves yellowish gray to white.

How to tell apart: Dyrnaesite-(La) is noticeably harder (Mohs 4.5 vs. 3).

Compare →

Often found alongside dyrnaesite-(la)

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

All properties

Chemical formula: Na₈Ce(La,REE)₂(PO₄)₆
Mohs hardness: 4.5
Density: 3.68 g/cm³
Colors: Pale yellowish green
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Orthorhombic
Crystal habit: Thin platy crystals
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: An accessory constituent (late magmatic) of hyperagpaitic arfvedsonite lujavrite in an alkaline igneous complex

Where rockhounds find dyrnaesite-(la)

Classic worldwide localities

Ilímaussaq alkaline complex, South Greenland

Field-hunting tip

Where it forms: An accessory constituent (late magmatic) of hyperagpaitic arfvedsonite lujavrite in an alkaline igneous complex. If you start seeing arfvedsonite, albite, microcline in float, you are in the right ground. Typical habit: thin platy crystals. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify dyrnaesite-(la)?+

Mohs hardness is 4.5. Luster: vitreous. The streak is white. Common colors include pale yellowish green.

Where is dyrnaesite-(la) found?+

Notable localities include Ilímaussaq alkaline complex, South Greenland.

What rocks look like dyrnaesite-(la)?+

Dyrnaesite-(La) is most often confused with Tundrite-(Ce), Tundrite-(Nd). A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with dyrnaesite-(la)?+

Dyrnaesite-(La) commonly co-occurs with Arfvedsonite, Albite, Microcline, Nepheline, Sodalite, Aegirine. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does dyrnaesite-(la) form in?+

Where it forms: An accessory constituent (late magmatic) of hyperagpaitic arfvedsonite lujavrite in an alkaline igneous complex. Working float back to the host body is the standard way to chase a fresh occurrence.

What is dyrnaesite-(la) used for?+

Dyrnaesite-(La) is used in collector.

Find dyrnaesite-(la) on the map

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