Hunting for lithium

Materials World magazine
,
1 May 2010
Mechanised lithogeochemical sampling at Mavis Lake

Michael Forrest talks to Gary Schellenberg, CEO of International Lithium Corp, Vancouver, Canada, about the company’s search for lithium resources.

Demand for lithium is predicted to rise due to its future use in electric transportation. This may increase demand by 50% in the next five years.

Gary Schellenberg, CEO of International Lithium Corp (ILC), Vancouver, Canada, explains that this is not a new phenomenon, ‘During the late 1940s and early 50s there was strong demand from the burgeoning nuclear industry in the USA and any suitable ground was pegged [for lithium]. The principal target was the mineral spodumene as it contained relatively high grades of lithium and was easily processed using conventional techniques. Lithium is associated with other incompatible elements in late-stage geological processes, that is, they are left out of the rock-forming process and concentrate in those late-stage deposits such as pegmatites’.

Pegmatites are found adjacent to large-scale intrusions where sufficient heat allowed the differentiation of the molten rock into separate minerals as cooling took place. One of the best places to find pegmatites is in areas where there was high regional heat flow, and preferably deep crustal flaws that allowed circulation to those depths that are thought to host many rare and minor metals.

The business, says Schellenberg, ‘is a project development company which has determined that the future demand in automotive batteries will outpace current production, and that new resources for these technological metals will be required’. He believes that the best place to develop new lithium mines is in stable countries such as Canada, which he says has good infrastructure, fair licensing, solid exploration potential and geological support, and a government that offers incentives in the early stages of a project.

‘Ontario in particular is pro-mining and offers a number of advantages. Firstly, the availability of geological reports, maps and surveys – the Ministry of Northern Development and Mines and the Ontario Geological Survey has databases that ILC has used extensively. The Government also offers a number of financial incentives for exploration including 100% deduction of expenses, flow-through tax incentives and a maximum CAN$6,000 grant to prospectors in return for one per cent royalty per property.

‘In production, the terms are even more generous with tax exemption for the first CAN$10m profit in the first three years, and 100% deduction of research and development costs against corporate income tax and mining tax related to mine output. Corporate income is taxed at an effective 12%. These incentives, along with all the logistical benefits, really make Ontario an important area for ILC,’ says Schellenberg.

Rich pickings

International Lithium Corp is looking at a number of locations within the province, including the Georgia Lake pegmatite field. Hosted in the central Quetico subprovince of the Superior Archean shield, the regional geology comprises metasedimentary greywacke and siltstone with rarer iron formations and conglomerates. Intrusions include I- (igneous origin) and S-type granites, along with minor basic and ultrabasic rocks.

The metasediments suggest a submarine basin of great lateral extent with typical unstructured turbidite fans derived from eroded granite-greenstone terrain to the north from the Wabigoon province, while the Wawa terrain to the south may also have provided material.

The properties of ILC are located near Forgan Lake within the Georgia Lake pegmatite field (GPF). One of the outstanding features of the areas is the abundance of granitic pegmatites close to and within the large masses of granitic rocks. These are mainly S-type granites (those derived from remelting sediments).

‘According to Dr Frederick Breaks, our consulting geologist, these granites were probably generated by extensive partial melting of clastic horizons at 2670±2 Ma. The GPF is entirely hosted within the medium-grade clastic metasedimentary rocks of the central Quetico sub-province,’ says Schellenberg.

Five types of rare-element pegmatites populate the GPF resulting from fractionation of residual melts produced from fertile granite masses. Related rare-element pegmatites have spread over the Georgia Lake area forming a 32km by 105km pegmatite field.

At Forgan Lake, at least six lithium-bearing pegmatites are known, four of which contain coarse to very coarse crystals of spodumene. The pegmatites vary in thickness from four to 14m in width and up to 60m in strike length while individual spodumene crystals can be up to 30cms in length. Geochemical analysis has indicated that the rare-element pegmatites of the GPF are possibly derived from three known parental granitic plutons in the area.

The 1.5km by five kilometre Pine Portage stock in particular, located along the western shore of Forgan Lake and approximately 2.5km west-southwest of the ILC licence, shows strong structural control evidenced by the consistent northeast strike also followed by the pegmatite dykes. This suggests that all the pegmatites were emplaced at the same time in a zone of regional fracturing.

The minerals found in the dykes (in order by volume) are microcline (a feldspar) spodumene, quartz, mica, and accessory amounts of tantalum (Ta) and niobium (Nb) oxides. In addition, other rare minerals containing beryllium (Be), cesium and rubidium (Rb) have also been found. Overall, a resource figure based on analysis 1950s drill cores gave a non-43-101 estimate of 11.7Mt grading 1.14% LiO2.

‘The high grades and significant tonnages of lithium and other rare elements in this part of Ontario provide an opportunity for ILC to participate in the growing rare element industry,’ states Schellenberg. ‘We are working towards upgrading by drilling and exploration to bring the resource into compliant reserves.’

Uncovered metals

About 20km east of Dryden, western Ontario, is the ILC Mavis Lake licence. The underlying geology contains the Ghost Lake Batholith, a 2,685Ma old intrusion that was the main source for numerous rare metals occurrences known as the Dryden Field Pegmatites. The host rocks are sediments and volcanics, while the structure is dominated by the Wabigoon fault, a major curvilinear regional structure.

During work in late 2009, 11 rare metal pegmatites, including the newly discovered RVL pegmatite, were found to fall into two groups – spodumene (Li-Rb-Be-Ta>Nb-B) and albite (Li>Rb–Be-Ta>Nb and Rb>Li-Be-Ta>Nb). Genesis is similar to the Forgan area, that is, fractional crystallisation of a fertile granite melt.

Fieldwork is continuing with lithogeochemical sampling. Analytical results from sampling last year gave weighted average values from channel samples of 1.22% Li, 92ppm cesium and 1,924ppm Rb. To the east and south samples with very high Ta values showed low lithium values typical of sodic aplite and albitite-rock units, important host-rocks for Ta mineralisation. ‘International Lithium Corp is moving ahead with these projects with the goal of developing them into resources in the short term. Subsequently, ILC aims to bring in strategic partners to jointly produce these technological metals,’ notes Schellenberg. ‘The market for these materials is forecast to expand with the increasing prevalence of high-tech applications and the demand for lithium. Furthermore, we believe that the additional value of the other rare metals in the pegmatites make these pegmatites economic and [will] finance a processing plant in Ontario. ILC is also developing lithium resources in evaporite brines in Nevada, USA and Argentina.’

Further information: International Lithium Corp