Naujaite
Agpaitic nepheline syenite rich in sodalite; sodalite + nepheline + alkali feldspar + eudialyte + arfvedsonite
A sodalite-rich agpaitic nepheline syenite with poikilitic texture from the Ilimaussaq complex, packed with blue sodalite, eudialyte and arfvedsonite.
- Mohs hardness
- 5-6
- Color
- gray-blue to greenish gray with blue sodalite
- Type
- igneous
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Overview
Naujaite is a distinctive sodalite-rich agpaitic nepheline syenite in which abundant early-formed sodalite crystals are enclosed (poikilitically) by large later crystals of alkali feldspar, nepheline, arfvedsonite (alkali amphibole), and eudialyte. The high sodalite content gives it a characteristic bluish-gray cast.
The rock is a major unit of the Ilímaussaq alkaline complex in South Greenland, named from the Naujakasik area. Like other Ilímaussaq rocks, it is agpaitic and enriched in rare alkali and rare-element minerals.
Naujaite is famous among mineral collectors for hosting a remarkable variety of rare minerals, including some first described there.
Formation & geology
Naujaite is interpreted to form by flotation accumulation of sodalite in agpaitic nepheline-syenite magma: lightweight sodalite crystals floated and concentrated near the roof of the magma chamber, later enclosed by crystallizing feldspar, nepheline, amphibole, and eudialyte to produce its poikilitic texture.
It occurs as a thick roof unit within the Ilímaussaq complex, a rift-related anorogenic alkaline intrusion in South Greenland. The extreme peralkaline, volatile-rich magma there generated naujaite along with lujavrite, kakortokite, and many rare minerals.
How to identify it
Look for a gray-blue to greenish coarse rock crowded with sodalite, often with a spotted or poikilitic look where pale feldspar/nepheline and dark arfvedsonite enclose the sodalite, plus pink eudialyte grains. Sodalite may show a blue tint and white streak.
The diagnostic features are the abundance of sodalite in an agpaitic nepheline syenite with eudialyte and sodic amphibole. The high sodalite content distinguishes naujaite from related Ilímaussaq rocks like lujavrite and kakortokite.
Look-alikes include other sodalite-bearing syenites; the combination of dominant sodalite, eudialyte, and poikilitic texture points to naujaite, typically confirmed by mineralogy.
Uses & significance
Naujaite has no major bulk commercial use, but it is exceptionally important to mineralogy and mineral collecting: the Ilímaussaq naujaites host dozens of rare and type-locality minerals, making specimens highly sought.
It also contributes to the rare-element (REE, zirconium, niobium, beryllium) significance of the Ilímaussaq complex as a whole, and its abundant sodalite links it to the wider use of sodalite as a decorative and lapidary material.
Scientifically, naujaite is a key example of crystal flotation and agpaitic magmatic processes.
Frequently asked questions
What makes naujaite distinctive?
Its abundance of sodalite enclosed poikilitically by feldspar, nepheline, amphibole, and eudialyte, giving a bluish, spotted appearance.
How did naujaite form?
Light sodalite crystals are thought to have floated and accumulated near the roof of an agpaitic magma chamber, then were enclosed by later minerals.
Where is naujaite found?
In the Ilímaussaq alkaline complex of South Greenland, where it forms a major roof unit.
Why do collectors prize naujaite?
It hosts an extraordinary number of rare and type-locality minerals found nowhere else in such abundance.
Naujaite guides
In-depth guides for identifying, valuing, and understanding Naujaite.
Naujaite identified by the community
Real specimens identified with Rock Identifier.
