The growing need for energy storage for e-mobility and other battery-intense applications has created a large interest in the key battery commodity lithium (Li). A recent hard rock lithium exploration and evaluation project is being conducted at Georgia Lake in Ontario, Canada. The Georgia Lake pegmatites contain Li- and rare metals-bearing spodumene in the area. In addition, previous work also identified beryl, columbite, molybdenite, amblygonite, apatite, and bityite, enhancing the Li and rare metals potential of the area.
The recent investigation focuses on the area where several spodumene-bearing pegmatites occur at the surface. Their length at the surface is between 50 m and 1.8 km along strike and 1-10 m width. More than 200 boreholes were drilled with a spacing below 50 m. The drill holes hit the pegmatites in a maximum depth of 350 m below surface, but continuation towards depth is expected. The varying Li2O content of the retrieved core samples reaches up to 2.7%.
The majority of the pegmatites are hosted by metasediments or biotite-rich granite. The internal zonation of the pegmatite dykes is in general characterized by a granitic or aplitic border zone with a spodumene, albite and quartz central zone. In some cases aplite layers and quartz tourmaline veins occur.
Mineralisation consists of coarse-grained fresh pale green spodumene crystals oriented perpendicular to the strike of the dyke. In some areas, the length of these crystals reaches up to 1 m and a thickness of up to 12 cm.
Five main pegmatite bodies have been newly modelled and a resource assessment made. The NI43-101 compliant technical report shows a measured resource of 1.89 million tons (Mt) @1.04% Li2O, an indicated resource of 4.68 Mt @1.00% Li2O, and an inferred resource of 6.72 Mt @1.16% Li2O. To extract these resources, the initial mine planning foresees open pit excavation of the top parts combined with underground sublevel stoping with backfilling of the deeper deposit.
Stephan Peters, Florian Lowicki, Ernst Bernhard Teigler, Torsten Gorka, Florian Beier & Jana Rechner
DMT GmbH and Co. KG, Germany