The Fen Carbonatite Complex

The Fen Carbonatite Complex is the remaining volcanic feeder pipe of a 580-million-year-old volcano with carbonate rich magma.

Fen Complex

Copyright Sven Dahlgren

The Fen Carbonatite Complex

The Fen Carbonatite Complex is the remaining volcanic feeder pipe of a 580-million-year-old volcano with carbonate rich magma (i.e. carbonatite). The volcano itself is of course long since gone.

The circular feature of the volcanic pipe is a little more than 2 km in diameter and contains several types of carbonatite rocks which vary in mineralogy and geochemistry.

Historically There has been mining activities in the area, with iron ore mining in hematitised carbonatite (“red rock”) in the east from 1657 to 1927, and niobium mining in calcite carbonatite (“søvite”) in the western part of the complex in from 1953 to 1965.

The current focus is on iron-dolomite carbonatite (“rauhaugite”), or FDC for short, in the central part of the complex. The FDC contains rare earth elements in the minerals bastnäsite and parisite (and minor synchysite and monazite) and has a grainsize and texture which enables efficient mineral separation.

Area and size

The part of the Fen Carbonatite Complex which consists of FDC covers an area of approximately 1,4 km2 and a depth of at least 1 km. Based on pre-existing information, provided by amongst others the Geological Advisor to the County Council and the Geological Survey of Norway, Golder has defined a JORC-compliant Exploration Target of 1,4-3,3 billion tonnes @ 0,4-2% TREO. Neodymium and praseodymium, which are important constituents in permanent magnets, account for 15-25% of the REE.

The Fen Carbonatite Complex is the largest known REE-deposit of carbonatite type in Europe. Rare Earths Norway is currently investigating the deposit through core-drilling and beneficiation tests.