Terrain Minerals has been granted a new, 100 per cent-owned exploration licence in Western Australia’s richly mineralised Mid West region.
The new ground, which the company has dubbed the "Wanarra" project, covers 15 square kilometres and adjoins Vault Minerals’ historic Rothsay gold mine, a functioning high-grade underground gold mine,part of Vault's broader Deflector operations and where mining dates back to 1898. Wanarra is also just 10km southwest of Terrain’s flagship Smokebush project, which hosts the company’s recent Lightning gold-silver discovery.
The property is 57km east-northeast of the agricultural centre of Perenjori, in the southern part of the Yalgoo Singleton greenstone belt. Terrain says the same geological sequences that host gold at the neighbouring Rothsay mine – narrow, sulphidic quartz veins in shear zones – extend southwards into its new tenement; However, the new ground is largely underexplored, leaving plenty of potential for gold discovery.
The Wanarra ground also harbours another layer of intrigue, sitting adjacent to the historic Rothsay beryl mine, which lies only 200m outside the northwest corner of its new tenement. The old mine, also known as the Seleka or Perenjori beryl mine, is an abandoned pegmatite pit 77km east of Perenjori and 3km west-southwest of Vault's Rothsay gold mine and its associated ghost town.
The old beryl show produced an estimated 297 tonnes of the mineral beryl - a silicate of the element beryllium - with the bulk of it coming from the Eastern pegmatite. The site's beryl-bearing pegmatites are divided into distinct zones, including a prominent quartz core and significant deposits of fluorapatite - which can fluoresce bright yellow under shortwave ultraviolet light.
The relationship between beryl and lithium pegmatites is highly intertwined with and driven by magma differentiation and structural zoning. Beryl is a primary indicator mineral for exploring lithium-caesium-tantalum (LCT) pegmatites and is often cited as an indicator of fractionated granite systems that often host lithium mineralisation.
Beryl possesses hollow hexagonal channels in its crystal matrix. In a lithium-rich environment, lithium ions may swap for beryllium ions in the crystal framework. By analysing the trace-element chemistry of beryl crystals, geologists can assess how chemically evolved a pegmatite system has become and whether it may be prospective for lithium mineralisation.
Interestingly, the fluorapatite accompanying the beryl is a calcium phosphate mineral which incorporates fluorine, making it the most common mineral in the apatite group. In pegmatite environments such as the Rothsay beryl mine, fluorapatite also often hosts trace elemental substitutions that change its properties.
These may include manganese, which substitutes for calcium, or rare earths elements such as cerium, lanthanum and yttrium, which also replace calcium, making fluorapatite a minor industrial source or indicator for rare earths minerals.
Terrain says the granite associated with the beryl mine extends into its Wanarra ground and has never been sampled for lithium or other critical minerals.
Historical exploration across the tenement between the 1990's and 2024 was little more than scout reconnaissance, comprising widely spaced surface geochemical sampling and a single shallow rotary air-blast drilling program in the tenement’s northeast corner. Terrain says that no previous work has systematically tested the area’s prospectivity.
Terrain Minerals executive director Justin Virgin said: “Wanarra sits immediately south of an operating high-grade gold mine and alongside a historic beryl pegmatite mine, yet it has seen only limited, early-stage exploration. That is a compelling combination for a new tenement. Lightning has shown this district still holds discoveries for explorers prepared to take a fresh look at ground others have passed over.
Terrain plans to apply the geological model it developed at its Lightning gold deposit, where it believes shear structures along the margins of granitic intrusions within the greenstone sequence control gold. The company says Wanarra has a comparable geological setting and the Lightning model could assist it to generate and categorise targets.
The initial work will comprise a low-cost, no-ground-disturbance program. It will involve reprocessing open-file aeromagnetic and radiometric data to better define structures that may host gold and to map outcropping areas and potential lithium-bearing granites. The company will then follow up with a first-pass rock chip sampling program on targets produced by data review, with samples to be assayed for gold, lithium and a full suite of other elements.
The strategy is consistent with the company’s objective of building its resource inventory by targeting repetitions of its Lightning-style gold mineralisation across the district, ahead of any future scoping study.
Terrain’s confidence in its exploration model stems from its success at the nearby Smokebush project, where it recently tabled a maiden inferred mineral resource for the Lightning deposit, comprising 677,000 tonnes at 2.5 grams per tonne (g/t) gold for 54,000 ounces and 7.2g/t silver for 156,500 ounces.
The company has also recently identified tungsten mineralisation across the Smokebush project, demonstrating its knack for uncovering potential in areas that may have been previously overlooked.
With a new, strategically located tenement in its back pocket featuring geological similarities to the nearby Rothsay gold mine and with tantalising hints of lithium potential nearby and tungsten further afield, Terrain is looking to prove that its rather unique exploration playbook can deliver once again.
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By Doug Bright
