FMF Minerals Gallery

To access to this FMF post with the image

Naujakasite
Ilímaussaq Intrusive Complex, Narsaq, Greenland
FoV= 3 x 3 cm;
Crystal: 1.5 x 1.2 cm

NAUJAKASITE is by no means an aesthetic mineral but it is deeply exciting conceptually, let us see why:

This string begins with two pieces of Steenstrupine, a mineral found only few places and in low quantities outside the Ilímaussaq Intrusion. It has very complex structure and around 20 different elements in the full formula, many of which are rare ones.
The Naujakasite is similar in distribution, it is practically never found at all outside the Intrusion, even if inside it is locally very common, it reach to be the main component of a rock. But in opposition to Steentrupine, its formula is surprisingly simple: Na6(Fe,Mn)Al4Si8O26
Now, in case of “strange combination of weird elements” we somehow “intuitively” accept that the formation event has been a rare one with only one or very few known occurrences on Earth. Nevertheless seeing such a simple formula with few and common elements, the uniqueness of the Ilímaussaq formation is somehow even more striking.

Strongly simplified, apart from the presence of many rare elements we are talking about a magma with very low concentrations of silicium (quarz is never found in most of the area in the central parts of the Intrusion!) and very high concentrations of sodium (Na) – an element present in high amounts in many Ilímaussaq minerals. (no wonder Sodalite has its type locality here…) (Author: kakov)