Naujaite Identification Guide
A guide to identifying naujaite, a rare sodalite-rich agpaitic nepheline syenite from Greenland, by its poikilitic sodalite and exotic minerals.
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What Naujaite Looks Like
Naujaite is a rare, coarse-grained agpaitic nepheline syenite distinguished by abundant sodalite in large poikilitic crystals that enclose other minerals. It is a hallmark rock of the Ilímaussaq alkaline complex in southern Greenland.
- Color: pale grey to bluish, often with blue or violet sodalite, and accents of yellow, pink, and black from accessory minerals
- Luster: vitreous to greasy
- Texture: coarse-grained; large sodalite hosts poikilitically enclose feldspar, nepheline, aegirine, eudialyte, and arfvedsonite
- Distinctive accessories: eudialyte (pink-red), aegirine (black-green needles), arfvedsonite (black), and rare sodium minerals
Step-by-Step Field ID Checklist
- Confirm a coarse, intrusive igneous texture (visible interlocking crystals, no foliation).
- Identify abundant sodalite — often bluish and fluorescent.
- Look for poikilitic sodalite enclosing smaller grains (a defining feature).
- Spot pink-red eudialyte and black aegirine/arfvedsonite as exotic accessories.
- Test sodalite fluorescence under UV (commonly bright orange).
Key Diagnostic Tests
- Hardness: sodalite 5.5-6, nepheline 5.5-6, feldspar 6 — overall moderate.
- UV fluorescence: sodalite typically fluoresces bright orange under shortwave/longwave UV — a strong clue.
- Acid: feldspathoids and sodalite are largely unreactive; some accessory minerals may alter.
- Density: moderate; certain accessories (eudialyte ~2.9-3.1) vary.
- Mineral assemblage: the agpaitic (Na-rich, exotic Zr/Ti-silicate) assemblage is diagnostic, especially eudialyte presence.
Common Look-Alikes and How to Tell Them Apart
- Ordinary nepheline syenite: lacks the dominant poikilitic sodalite and the agpaitic accessories (eudialyte, complex Na-Zr silicates).
- Lujavrite: a related Ilímaussaq agpaite, but lujavrite is foliated/laminated with aligned aegirine and eudialyte; naujaite is non-foliated with poikilitic sodalite.
- Kakortokite: another Ilímaussaq rock, but it is rhythmically layered (black-red-white banding) rather than sodalite-poikilitic.
- Sodalite-bearing syenite/sodalite ornamental rock: simpler mineralogy, no eudialyte or agpaitic suite.
Where It Is Found
Naujaite is essentially restricted to the Ilímaussaq alkaline complex, southern Greenland, where it forms a major part of the layered agpaitic intrusion. Comparable rocks are extremely rare elsewhere.
Frequently asked questions
What is naujaite?
Naujaite is a rare sodalite-rich agpaitic nepheline syenite, defined by large poikilitic sodalite crystals enclosing other minerals, and famous from the Ilímaussaq complex in southern Greenland.
How do you identify naujaite?
Look for a coarse intrusive rock dominated by poikilitic sodalite (often fluorescing bright orange under UV) with exotic accessories like pink-red eudialyte and black aegirine and arfvedsonite.
What is the difference between naujaite and lujavrite?
Both are Ilímaussaq agpaites, but naujaite is non-foliated with poikilitic sodalite, while lujavrite is foliated or laminated with aligned aegirine and eudialyte.
Where does naujaite come from?
It is found almost exclusively in the Ilímaussaq alkaline complex of southern Greenland, with comparable rocks being extremely rare worldwide.
Naujaite identified by the community
Recent Naujaite specimens identified with Rock Identifier.
