Summary:
Deposit Type
The Tanbreez deposit is classified as a peralkaline igneous REE-Zr deposit, specifically hosted within the Ilimaussaq Alkaline Complex in South Greenland. It is, enriched in zirconium (Zr), niobium (Nb), and other critical metals. The formation Setting is a Mesoproterozoic continental rift-related intrusion (Gardar Rift) and is estimated at -1.16 billion years
The Tanbreez ore deposit is a highly fractionated ortho-magmatic tantalum-niobium-zirconium-rare earth element (REE) deposit in the southern part of the 1.13-giga-annum-old Ilimaussaq intrusive complex in South Greenland. The commodities are hosted in the zirconosilicate mineral cudialyte, occurring concentrated in kakortokite at the floor of the exposed intrusion.
The kakortokite sequence is outcropping over an area of 5×2.5km and has a total thickness of 350 m, estimated at 4.7 billion tonnes that does not indicate any certainty of hosting mineralization. The estimate is conceptual in nature. It is based on extensive historic and Tanbreez exploration drilling (414 holes) coupled with the exposures in multiple creek sections. Investors should not place undue reliance on this information.
Linear correlations between ZrO2 and individual REE indicate that eudialyte is by far the main REE-bearing mineral in kakortokite. Estimated average grades at 1.5% ZrO2 cut off are 2.4% ZrO2, 0.2% Nb2Os, and 0.6% total rare earth oxides, of which heavy REE make up 28% (including yttrium). Eudialyte, feldspar, and arfvedsonite concentrates can be obtained by crushing and milling the ore, with subsequent high-intensity magnetic separation. It is anticipated that apart from eudialyte, feldspar and arfvedsonite concentrates can be used.
Mineralization
The Tanbreez Project is one of the world's most significant rare earth element (REE) deposits, hosted in the Ilimaussaq Alkaline Complex. The mineralization is primarily associated with the peralkaline syenite rocks, especially the kakortokite and lujavrite layers.
Kakortokite is the dominant host rock for mineralization at Tanbreez. It is composed of rhythmic layers of feldspar, arfvedsonite, aegirine, and eudialyte. The mineral eudialyte is the primary REE-bearing phase. Lujavrite (Secondary Host) is a darker, REE-enriched nepheline syenite that also contains eudialyte, but in a more complex mineralogical setting. The units are enriched in zirconium, niobium, and tantalum.
The primary REE-bearing mineral is Eudialyte, the key carrier of light and heavy REEs, along with zirconium (Zr), niobium (Nb), and tantalum (Ta). Unlike monazite and bastnäsite, eudialyte has low uranium (U) and thorium (Th), making it attractive for mining. Heavy REEs include Dysprosium (Dy), Yttrium (Y), Terbium (Tb). Light REEs include Neodymium (Nd), Praseodymium (Pr), Lanthanum (La). The deposit is especially rich in HREEs, which are critical for high-tech applications.
Additional mineralization includes Zirconium (Zr), and Niobium (Nb) hosted in eudialyte and catapleiite minerals. Zirconium is an important material for nuclear reactors and ceramics. Niobium is used in superalloys and high-strength steels. Iron and Titanium are present as aegirine (iron silicate) and ilmenite (iron-titanium oxide). Unlike many REE deposits worldwide, Tanbreez has low levels of radioactive elements (U, Th), making processing easier.
Kakortokite
The kakortokite unit is a distinctively banded group of eudialyte bearing nepheline syenite layers which are the lowest exposed unit in the intrusion. The kakortokite has been the subject of the most extensive exploration in the whole intrusion with over 400 holes, over 709 tonnes of bulk samples and over 500,000 assays. The kakortokite is characterised by three groups of minerals, each with a distinctive colour:
- Red cudialyte, ~2-6% ZrO2
- Blackarfvedsonite, 1-2% ZrO2
- Whitefeldspar, nepheline and sodalite, 1% ZrO2
The deposit consists of the 3 bands, one of each colour that make up a unit with over 50 units mapped. However, each band itself is economic with the average grade of about 1.9% ZrO2. Bands range from Im to over 10m thick. They persist over large areas seen on the cliff face.
Eudialyte is a rare, complex silicate mineral that serves as an important source of zirconium, niobium, and heavy rare earth elements (HREEs). Tanbreez is one of the largest known eudialyte-rich REE deposits, providing a strategic, non-Chinese source of heavy rare earths. Low environmental impact due to minimal uranium and thorium content. Western-controlled REE supply, reducing reliance on Chinese production.
The Tanbreez rare earth element (REE) deposit in South Greenland is a world-class mineralised unit hosted within the Ilímaq intrusive complex. The deposit is primarily composed of kakortokite, a layered rock rich in zirconium (Zr), niobium (Nb), tantalum (Ta), and REEs, particularly in the mineral eudialyte. Covering an area of approximately 5 x 2.5 km with a thickness of 335 meters.
Geologically, Tanbreez is part of the Meso-Proterozoic Gardar Province, formed around 1.13 billion years ago. The complex is made up of three main phases of rock formations, with the kakortokite sequence positioned in a saucer-shaped structure, dipping at 10-15 degrees. The deposit is bounded by the Black Madonna unit below and lujavrite above.
Ore grades in the deposit include 1.75% ZrO2, 0.18% Nb2O5, and 0.6% total REO (including yttrium), with heavy REEs making up approximately 30% of total REO content. The deposit is notable for its low uranium (20 ppm) and thorium (53 ppm) content, making it more viable for processing (announced in the the” Schonwandt Paper).
Size of the Kakortokite Unit
The Kakortokite Unit within the Tanbreez REE deposit in South Greenland is a large, well-exposed, and layered rock formation that serves as the primary host for zirconium, niobium, tantalum, and rare earth elements. The body spans an area of approximately 5 km by 2.5 km and has a total thickness of-350 meters based on deep drilling, making it one of the most substantial REE-bearing formations globally.
Structurally, the kakortokite sequence is characterized by a saucer-shaped geometry, with steep to vertical layers at the periphery that transition into a gentle dip of 10-15 degrees towards the centre. It is divided into three distinct subunits: the Lower Layered Kakortokite (LLK) at 209 meters, the Slightly Layered Kakortokite (SLK) at 35 meters, and the Transitional Layered Kakortokite (TLK) at 40 meters. The deposit is overlain by lujavrite and underlain by the Black Madonna unit, which has been encountered in drill cores but remains unexposed at the surface. The substantial thickness, extensive exposure, and well-defined stratification of the kakortokite make it a world-class mineralised body, holding immense economic and industrial significance.