29 July 2002.

Southern part of the Ilímaussaq Intrusion

(Kangerluasuk)

First we visited the contact zone augite syenite/naujaite to the west of Sørensen ø (ø = island).

Augite syenite.

Naujaite. A sodalite-nepheline syenite.

Next we went ashore near the stream "Lille elv" (in the naujaite zone).

Arfvedsonite (sodium rich amphibole). The Ilímaussaq Intrusion is the type locality to many of the more well known agpaitic minerals such as arfvedsonite, and the crystals can indeed be very large.

2 generations of arfvedsonite crystals.

 1st generation: thickness 3-4 mm

2nd generation: "rosettes" (radiating Arfvedsonite needles)

The Ilímaussaq Intrusion is one of worlds best location for arfvedsonite. It is named after the Swedish chemist. Johan A. Arfvedson.

Layered intrusion - kakortakites ("Kringlerne"). (Photo by Roger Baker)