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Jacupiranga complex

Naujakasite Lujavrite

Lujavrite: Melanocratic agpaitic variety of nepheline syenite rich in eudyalite, arfvedsonite and aegirine with perthitic alkali feldspar. A pronunced igneous lamination is characteristic, as is the abundance in minerals rich in incompatible elements such as ussingite, naujakasite, steenstrupine, rosenbuschite, villiaumite etc. The name come from Luijaur, now Lujavr-Urt, Lovozero complex, Kola, Russia.

Lujavrite is a meso- to melanocratic agpaitic to hyperagpaitic syenite with a pronounced lamination caused by the orientation of mafic minerals and, in part, felsic minerals such as feldspars. The two most abundant varieties of lujavrite in Ilímaussaq are named based on colour: in green lujavrite the predominant mafic mineral is aegirine; in black lujavrite, the main mafic mineral is arfvedsonite. The felsic minerals in lujavrite are nepheline, albite, microcline, and sodalite. Lujavrites are fine grained (up to 0.6 mm), but sodalite grains can be up to 2 mm and mafic minerals up to 1 mm. A coarser type of lujavrite is called M-C-lujavrite (M-C stands for medium to coarse grained), in which the individual grains can reach sizes of more than one cm, and are locally pegmatitic. A fourth type, naujakasite lujavrite, contains naujakasite and is associated with the highly agpaitic stage of the complex. In these lujavrites, naujakasite generally occurs at the expense of nepheline. Locally the lujavrite contains up to 75 % volume naujakasite. The water-soluble mineral villiaumite is abundant in most of the lujavrites but has been leached out in some near-surface rocks. Lujavrite is the rock unit containing the highest amounts of incompatible elements and is the major ore of the Kvanefjeld deposit.

luajvrite(analcime).jpg

Analcime-rich lujavrite. From Hunterian Museum Geology Collections

Steenstrupine (dark, big crystals) in a lujavrite. From Friends of Minerals Forum.

Naujakasite-rich lujavrite. Arfvedsonite (black), villiaumite (red) and naujakasite (lozenge-shaped).

Sample kindly given to me by James Connelly (Natural History Museum of Denmark).

Bibliography

• Sørensen, H. (Ed.). (2001). The Ilímaussaq alkaline complex, South Greenland: status of mineralogical research with new results (No. 301). Geological Survey of Denmark and Greenland, Ministry of Environment and Energy.
• Hunt, E. J., Finch, A. A., & Donaldson, C. H. (2017). Layering in peralkaline magmas, Ilímaussaq Complex, S Greenland. Lithos, 268, 1-15.

Photo
Naujakasite crystals (with rhomb-shaped sections) and arfvedsonite (green) in a Lujavrite. Ilímaussaq, Greenland. PPL image, 2x (Field of view = 7mm)	Naujakasite crystals (I order gray) and arfvedsonite in a Lujavrite. Ilímaussaq, Greenland. XPL image, 2x (Field of view = 7mm)	Naujakasite crystals (with rhomb-shaped sections) and arfvedsonite (green) in a Lujavrite. Ilímaussaq, Greenland. PPL image, 2x (Field of view = 7mm)
Naujakasite crystals (with rhomb-shaped sections) and arfvedsonite (green) in a Lujavrite. Ilímaussaq, Greenland. PPL image, 2x (Field of view = 7mm)	Naujakasite crystals (I order gray) and arfvedsonite in a Lujavrite. Ilímaussaq, Greenland. XPL image, 2x (Field of view = 7mm)	Naujakasite crystals (with rhomb-shaped sections) and arfvedsonite (green) in a Lujavrite. Ilímaussaq, Greenland. PPL image, 2x (Field of view = 7mm)
Naujakasite crystals (colorless) and arfvedsonite (green) in a Lujavrite. Ilímaussaq, Greenland. PPL image, 2x (Field of view = 7mm)	Naujakasite crystals (colorless) and arfvedsonite (green) in a Lujavrite. Ilímaussaq, Greenland. PPL image, 2x (Field of view = 7mm)	Naujakasite crystals (colorless) and arfvedsonite (green) in a Lujavrite. Ilímaussaq, Greenland. PPL image, 2x (Field of view = 7mm)
Naujakasite crystals (colorless) and arfvedsonite (green) in a Lujavrite. Ilímaussaq, Greenland. PPL image, 2x (Field of view = 7mm)	Naujakasite crystals (colorless) and arfvedsonite (green) in a Lujavrite. Ilímaussaq, Greenland. PPL image, 2x (Field of view = 7mm)	Naujakasite crystals (I order gray) and arfvedsonite (green) in a Lujavrite. Ilímaussaq, Greenland. PPL image, 2x (Field of view = 7mm)
Naujakasite crystals (colorless) and arfvedsonite (green) in a Lujavrite. Ilímaussaq, Greenland. PPL image, 2x (Field of view = 7mm)	Naujakasite crystals (I order gray) and arfvedsonite (green) in a Lujavrite. Ilímaussaq, Greenland. PPL image, 2x (Field of view = 7mm)	Naujakasite crystals (colorless) and arfvedsonite (green) in a Lujavrite. Ilímaussaq, Greenland. PPL image, 2x (Field of view = 7mm)
Naujakasite crystals (I order gray) and arfvedsonite (green) in a Lujavrite. Ilímaussaq, Greenland. PPL image, 2x (Field of view = 7mm)	Naujakasite crystals (colorless) and arfvedsonite (green) in a Lujavrite. Ilímaussaq, Greenland. PPL image, 2x (Field of view = 7mm)	Naujakasite crystals (I order gray) and arfvedsonite (green) in a Lujavrite. Ilímaussaq, Greenland. PPL image, 2x (Field of view = 7mm)
Naujakasite crystals (colorless) and arfvedsonite (green) in a Lujavrite. Ilímaussaq, Greenland. PPL image, 2x (Field of view = 7mm)	Naujakasite crystals (I order gray) and arfvedsonite (green) in a Lujavrite. Ilímaussaq, Greenland. PPL image, 2x (Field of view = 7mm)	Naujakasite crystals (colorless) and arfvedsonite (green) in a Lujavrite. Ilímaussaq, Greenland. PPL image, 2x (Field of view = 7mm)
Naujakasite crystals (colorless) and arfvedsonite (green) in a Lujavrite. Ilímaussaq, Greenland. PPL image, 10x (Field of view = 2mm)	Naujakasite crystals (colorless) and arfvedsonite (green) in a Lujavrite. Ilímaussaq, Greenland. PPL image, 10x (Field of view = 2mm)	Naujakasite crystals (colorless) and arfvedsonite (green) in a Lujavrite. Ilímaussaq, Greenland. PPL image, 10x (Field of view = 2mm)
Naujakasite crystals (colorless) and arfvedsonite (green) in a Lujavrite. Ilímaussaq, Greenland. PPL image, 10x (Field of view = 2mm)	Naujakasite crystals (colorless) and arfvedsonite (green) in a Lujavrite. Ilímaussaq, Greenland. PPL image, 10x (Field of view = 2mm)	Naujakasite crystals (colorless) and arfvedsonite (green) in a Lujavrite. Ilímaussaq, Greenland. PPL image, 10x (Field of view = 2mm)
Naujakasite crystals (colorless) and arfvedsonite (green) in a Lujavrite. Ilímaussaq, Greenland. PPL image, 10x (Field of view = 2mm)	Naujakasite crystals (colorless) and arfvedsonite (green) in a Lujavrite. Ilímaussaq, Greenland. PPL image, 10x (Field of view = 2mm)	Naujakasite crystals (colorless) and arfvedsonite (green) in a Lujavrite. Ilímaussaq, Greenland. PPL image, 10x (Field of view = 2mm)
Naujakasite crystals (colorless) and arfvedsonite (green) in a Lujavrite. Ilímaussaq, Greenland. PPL image, 10x (Field of view = 2mm)	Naujakasite crystals (I order gray) and arfvedsonite (green) in a Lujavrite. Ilímaussaq, Greenland. ZPL image, 10x (Field of view = 2mm)	Naujakasite crystals (colorless) and arfvedsonite (green) in a Lujavrite. Ilímaussaq, Greenland. PPL image, 10x (Field of view = 2mm)
Naujakasite crystals (colorless) and arfvedsonite (green) in a Lujavrite. Ilímaussaq, Greenland. PPL image, 10x (Field of view = 2mm)	Naujakasite crystals (colorless) and arfvedsonite (green) in a Lujavrite. Ilímaussaq, Greenland. PPL image, 10x (Field of view = 2mm)	Naujakasite crystals (colorless) and arfvedsonite (green) in a Lujavrite. Ilímaussaq, Greenland. PPL image, 10x (Field of view = 2mm)
Naujakasite crystals (twinned) in a Lujavrite. Ilímaussaq, Greenland. XPL image, 10x (Field of view = 2mm)	Naujakasite crystals (twinned) in a Lujavrite. Ilímaussaq, Greenland. XPL image, 10x (Field of view = 2mm)	Naujakasite crystals (twinned) in a Lujavrite. Ilímaussaq, Greenland. XPL image, 10x (Field of view = 2mm)