Lot A2

Rare Metals

Identification of Lithium Mineral Ores (Lepidolite and Spodumene), Tin Ores (Cassiterite), Tantalum and Niobium Ores (Columbite-Tantalite)

Study Areas: Ado-Ekiti, Apomu, Calabar, Lafiagi, Udegi and Wamba-Kurra

“The most ambitious project the Nigerian Geological Survey Agency (NGSA) is currently handling,” Says Dr Abdulrazaq, “is the National Integrated Mineral Exploration Project (NIMEP), which is government’s rapid response to the dearth of investible geoscience data in the country. The National Integrated Mineral Project (NIMEP) is the first of its kind and it is envisaged that the exploration exercise is expected to generate targets that will attract investment into the sector, or the commodities considered.” – Mining Review Africa

What the NIMEP project aims to achieve, is to reduce the risk component along the identified mineral corridors within Nigeria and attract investment into the sector. The NIMEP Project subdivided the exploration activities into specific commodity groups. In connection with the Ministry of Mines and Steel Development (MMSD) and Nigeria Geological Survey Agency (NGSA) is undertaking the exploration of critical metals like lithium, tin, tantalum and niobium.

FAVOURABLE CHARACTERISTICS OF MINERALISED RARE-METAL PEGMATITES

  • Pegmatites are very coarse-grained igneous rocks of granitic composition that are defined by London (2008) as having a distinctive graphic texture (an intergrowth of quartz and feldspar), which is a eutectic texture and therefore crystallised from a melt.
  • Pegmatites can be simple or complex, zoned or unzoned, and since they are crystallised from a late-stage melt, they tend to be enriched in incompatible and rare-metal elements such as Li, Be, Nb, Sn, Ta, Th, U,Wor Zr.
  • Preferred host lithologies for LCT or NYF pegmatites include amphibolites or mafic schists; metasedimentary sequences comprising mica-schists, BIF, amphibolites, quartzite, greywackes, carbonates etc.; and metamorphic grade usually in the amphibolite facies.
  • Fertile granites, usually S- or A-type containing garnet and muscovite, are typically characterised by similar age within the pegmatite group or close to it.
  • Pegmatite classification and ranking can be scored on the basis of relative size (“if you can spit over it, it’s not economic” – overheard in a bar somewhere*), geochemistry, mineralogy, zonation and historic production.
  • Specific consideration is given to production of “pathfinder” commodities and minerals like tantalite (with Ta>Nb or Sn rich concentrates), pollucite, the types of gemstone produced etc. within a known pegmatite belt or field.

NIGERIAN GEOLOGY AND PEGMATITES

  • The granitic terranes in Nigeria are conducive to the development of Lithium-Cesium-Tantalum (LCT) and Niobium-Yttrium-Niobium-Fluorine (NYF) families of pegmatites.
  • The Western Terrane is characterised by low-grade metamorphism, while the Eastern Terrane is characterised by high-grade metamorphism.
  • The LCT pegmatites tend to be associated with post-collisional, potassic met- to peraluminous (S-/A- type) “Older” (late Pan-African, c. 640-600 Ma and 600-580 Ma) granites formed from mixed mantle and crustal sources occurring in both the Western and Eastern terranes. These pegmatites are commonly enriched in Li, Cs, Ta, Rb, Be, Sn, B, P and F.
  • The NYF pegmatites tend to be associated with syn-collisional (A-type) “Younger” (c. 170-160 Ma) granites and ring complexes of the Jos Plateau, which are restricted to the Eastern Terrane. They are commonly enriched in Nb over Ta, with appreciable levels of Ti, REE+Y, Zr, Th, U, Sc and F.

ADO-EKITI PROJECT AREA

  • At least 9 potential pegmatite targets (up to 500m x 1km) and numerous occurrences located along structural lineaments within a mafic schist belt.
  • Grab samples returning up to 4.5 % Li2O and 850 ppm Ta from several positions with moderate tantalum and minor tin credits.
  • Observed mineral species include muscovite, spodumene, lepidolite, beryl, garnet, tantalite, black and green tourmaline.

APOMU PROJECT AREA

  • At least 17 potential pegmatite targets and numerous occurrences within the project area have been identified.
  • Grab samples returning up to 2.8 % Li2O from several positions with moderate tantalum and minor tin credits.
  • Observed mineral species include muscovite, spodumene, lepidolite, beryl, garnet, tantalite and tourmaline.

LAFIAGI PROJECT AREA

  • At least 18 potential pegmatite targets and numerous occurrences within the project area have been identified.
  • Grab samples returning up to 8.8 % Li2O, 0.4 % Sn and 1,000 ppm Ta from several positions.
  • Observed mineral species include muscovite, spodumene, lepidolite, tantalite and tourmaline.

UDEGI PROJECT AREA

  • At least 49 potential pegmatite targets and numerous occurrences within the project area have been identified.
  • Grab samples returning up to 8.1 % Li2O, 0.6 % Sn and 10,000 ppm Ta from several positions.
  • Observed mineral species include spodumene, lepidolite, garnet and tourmaline as well as columbite-tantalite, cassiterite.

WAMBA-KURRA PROJECT AREA

  • At least 27 potential pegmatite targets and numerous occurrences within the project area have been identified.
  • Grab samples returning up to 2.5 % Sn and 870 ppm Ta from several positions.
  • Observed mineral species include cassiterite, columbitetantalite, garnet and tourmaline.
  • Possibly associated with the historic tin mining production in the Jos area since 1912.

© Copyright - NIMEP