Desktop reconnaissance and core library mining – these are two phrases that are appearing more regularly in mining companies’ announcements about their exploration programmes.
With booming demand for battery and critical metals across the globe, many junior explorers are combing through various geological departments’ historic databases and, where possible, ancient core libraries – and in some cases old mullock heaps.
What they are finding is that ancient discoveries of now heavily in-demand minerals like lithium were ignored back-in-the-day, while some base and precious metals finds were ignored as they were not considered commercial in a period of very low commodity prices.
St George using history to hunt battery metals
One Australian company that is using historical data to strategically build up its critical minerals portfolio is St George Mining Limited (ASX: SGQ).
St George’s executive chairman, John Prineas, and his highly regarded technical team, have built up a well-earned reputation for having their fingers on the pulse when it comes to new opportunities.
The company is particularly renowned for its ability to identify new and old geological plays that have the opportunity to create value for St George’s shareholders.
Already a significant nickel explorer in Western Australia (WA), St George has recently used its expertise in combing through historical data to identify some promising new critical minerals opportunities in WA.
The company has just entered into a binding agreement for an option to acquire 100% of the historic Woolgangie Project, located in WA’s minerals-rich Eastern Goldfields. To date the Woolgangie Project has received only superficial previous exploration for lithium-bearing pegmatites and limited exploration for other types of mineralization.
While exploration has been limited in the area, historic activities have identified lithium, rare earths, and base metals potential.
Numerous pegmatites have been previously mapped for many kilometres within the western tenements along the Ida Fault, where the tenements lie along the margin of a known lithium province.
St George is also chasing rare earths and base metal opportunities in these new tenements.
Historical drilling in 2010 by Mincor Resources (ASX: MCR) identified several wide zones of rare earth anomalism while exploring for nickel sulphides.
Meanwhile,historical drilling by Emu NL (ASX: EMU) encountered extensive near-surface copper sulphide mineralization that warrants further follow-up exploration.
St George is conduction an ongoing review of historical data in the lead-up to undertaking work programmes.
“The option over Woolgangie provides a strategic and cost-effective pathway to grow St George’s already substantial lithium and critical metals opportunities in WA, complementing our success at Mt Alexander and the potential of our other projects including Paterson, Ajana, and Broadview Projects,” Mr Prineas said.
“We are excited by the potential for systematic exploration at Woolgangie to deliver a major discovery at this highly prospective but underexplored landholding.”
Shree unveils Dundas Project’s lithium history
Mapping by Shree Minerals Ltd (ASX: SHH) has identified lithium potential in old aircore drilling spoil from 10 holes from a Pan Aust Exploration drilling programme in Western Australia’s south in 1998.
Despite the sample piles being eroded and covered by heavy vegetation regrowth over time, Shree says sample chips were readily identified and collected for sampling. Importantly, Shree mapping identified three holes containing pegmatite chips.
“The identification of pegmatites in historical drill chips confirms the findings of historical drill logs by past explorers that intersected gold mineralization,” executive director, Sanjay Loyalka, said.
“Many of the holes drilled intersected pegmatites but these were not the target of the exploration at the time and hence were not assayed for lithium or lithium pathfinder elements. It has significant implications for additional discoveries within our tenements.
“These implications are even more significant because Liontown’s (ASX: LTR) world-class Buldania Lithium project is only 25km away. The structural setting at Buldania (adjacent to Zuelika Shear) resembles the same settings within Shree’s tenements, highlighted by major regional structures, as suggested from aerial magnetic images.”
Ragusa also hunting historic lithium targets
Further to the north in Australia’s Northern Territory, Ragusa Minerals Limited (ASX: RAS) has identified new lithium opportunities through recently received data from a historic diamond drill-hole in the Tank Hill Prospect area.
The results have confirmed a significant historic pegmatite intercept with logged spodumene and corresponding elevated lithium withing the company’s NT Lithium Project – located in the highly prospective Litchfield Pegmatite Belt located approximately 120km south of Darwin.
The diamond drill-hole (MDD004) was completed by May drilling during 2019, with the assay and geological logging data only provided recently to Ragusa. The pegmatite drill-intercept starts and finishes well within the lithium depleted zone (top ~65m below surface), accounting for the anomalous Li2O grades intersected.
Importantly, the Li2O grades correspond with the geological logging conducted, which describes much of the interval as containing spodumene and spatially with the surface outcrop containing abundant lepidolite (rock chip sample 140333). The surface expression of the pegmatite indicates an ~12m true thickness that is also supported by the downhole data.
Chasing historic gold in Arizona
Elsewhere, Gold Basin Resources Corporation (TSXV: GXX) recently revealed that its review and analysis of historical drill data on the Red Cloud deposit claims has highlighted the exciting potential of over 1km of potential strike extension of the mineralization of the Stealth deposit at its 100%-owned Gold Basin project in Mohave County, Northern Arizona, US.
Whilst gold intersections at this location were previously known by the company a new analysis of the data has enabled an accurate geo location of the holes in relation to the major structural features and the Stealth deposit.
The mineralization intersected historically at Red Cloud starts from near surface and corresponds closely with the form and grade intersected with the company’s drilling at Stealth in its last drill programme.
The company is also in the process of further evaluating a number of historical drillholes drilled on an East-West line between Cyclopic and Stealth in the northern section of the new claim areas that have also intersected gold mineralization.
Termites and history identifies Senegal uranium opportunity
Science and nature have come together in Senegal, where Haranga Resources Limited (ASX: HAR) recently used historical drilling results and termite mound sampling to identify promising new uranium targets at its Saraya permit.
The new results were integrated with the results of a historical termite mound sampling programme conducted during 2012 by Prospectiunii and comprising 5,843 samples.
Haranga’s technical team also assessed results from holes drilled by Cogema and Areva between the mid-1970s and 2009 in the northern portion of the Saraya permit. Historical drilling was aimed at testing various soil-sampled and trenched regional uranium anomalies.
The programme yielded seven large uranium anomalies comprising 140 samples with uranium concentrations ranging between 7.0ppm and 17ppm. In addition, the programme returned numerous smaller anomalies containing up to 15ppm uranium.
