Summary:
Deposit type
Bonnie Claire is a large lithium-boron carbonate/salt-bearing sedimentary-hosted deposit.
Bonnie Claire deposit initially described by Asher-Bolinder (1991) as “Li-smectites of closed basin,” and more recently by Putzulo et. Al (2025) as a Volcano-sedimentary (VS) deposit. This classification is supported by observed mineralogy in XRD data, which reveals the presence of smectite, illite-muscovite, analcime, halite, and calcite—indicating deposition in a saline, closed-basin (endorheic) environment with strong volcanic input. The lithium is likely hosted in multiple phases, including Li-substituted smectite and micas, as well as potentially in zeolitic phases like analcime or as Li salts within fine-grained evaporitic material. Bonnie Claire shares geological affinities with other Nevada-based VS-type Li-boron (B) deposits such as Thacker Pass, McDermitt, Rhyolite Ridge, and Nevada North, all of which occur within lacustrine basins proximal to Li-B-enriched volcanic provinces.
Bonnie Claire exhibits many of the hallmark features of fault-bounded lithium-boron claystone deposits, particularly those formed in structurally complex, hydrologically closed basins:
• Lithium- and boron-enriched sedimentary host rocks are part of a lacustrine sequence deposited under a hydrologically closed regime. This setting inhibits loss of mobile elements like Li and B, which would otherwise be leached in open fluvial systems. The XRD analyses confirm the presence of authigenic and detrital minerals typically associated with this environment, including smectite, illite-muscovite, and analcime, along with evaporative phases such as halite and calcite.
• The deposit lies within the structurally confined Sarcobatus Flat Basin, a product of Basin and Range extension superimposed by dextral shearing along the Walker Lane Belt. This tectonic interaction created a narrow but deep transtensional basin, capable of accumulating significant sediment thickness and maintaining prolonged hydrologic isolation—conditions ideal for element concentration.
• Sedimentation occurred in a playa lake setting under arid to semi-arid conditions, characterized by ephemeral and seasonal lakes. The high evaporation-to-recharge ratio enhanced the accumulation of lithium and boron within fine-grained lacustrine clays and zeolitized ash beds. XRD results support this with widespread smectite and illite-smectite mixed layers, as well as analcime—an indicator of saline, alkaline diagenetic conditions.
• The basin’s proximity to the Timber Mountain–Oasis Valley volcanic complex (active from ~16 to 6 Ma, peaking around 11 Ma) provided a sustained source of Li and B.
Geology and Mineralization
Bonnie Claire is the lowest-elevation intermediate size playa-filled valley in a series of similar topographic features. It has a playa floor of about 100 square kilometers (km2) that receives surface drainage from an area of about 1,300 km2 . The Bonnie Claire basin lies within an extensional graben system between two Quaternary northwest-southeast faults with both normal and strike-slip components. The general structure of the middle part of the Bonnie Claire basin (Claim area) is known from geophysical surveys to be a graben structure with its most down-dropped part on the east-northeast side of the basin along the extension of a few normal faults.
The area surrounding the Project area is dominated by uplifted basement rocks that were mostly built from silicic ash-flow tuff.
At the surface, the property is characterised by a central Quaternary alluvial mud flat, surrounded by Quaternary alluvial fans, which erode from the surrounding mountain ranges. The Quaternary cover is approximately 10 metres thick and gives way to a thick sequence of volcaniclastic sediments.
The fluvial quaternary sedimentary deposits have been subdivided into Older Alluvium and Younger Alluvium. Older Alluvium has been deformed and dissected in places, and parts of it are cemented into a firm fanglomerate. Younger Alluvium consists mainly of unconsolidated gravel, sand, silt, and clay, which form recent fluvial and lacustrine deposits.
Drilling to date has shown that within the Project area, the extensional sedimentary basin has been filled by a thick package of volcaniclastic sand, silt, and clay. Drilling to date has demonstrated that the sedimentary package is approximately 900m thick within the resource area and may be thicker in the northern part of the Property. Geophysical surveys and drill intercepts have suggested that these sediments are predictable and laterally continuous, dipping 5 to 10 degrees to the east or northeast.
The Quaternary basin sediments at the Bonnie Claire Project host significant lithium and boron mineralization. Elevated lithium concentrations have been encountered at the surface within the alluvial fans and playa, with mineralization increasing in intensity with depth, extending down to the basement at approximately 945 meters in drillhole BC-2301C.
Lithium and boron mineralization varies according to the dominant lithologies within the sedimentary sequence:
• Upper Claystones exhibit moderate lithium and boron mineralization, with lithium values ranging from 55 to 2,210 ppm and boron ranging from 5 to 8,900 ppm. This interval, averaging 135 meters in thickness, is referred to as the Upper Zone of mineralization at Bonnie Claire.
• Upper Sandstones show very low lithium and variable boron concentrations, ranging from 25 to 1,420 ppm lithium and 0 to 7,130 ppm boron.
• Lower Claystones contain variable to very high lithium and boron mineralization, with lithium concentrations ranging from 133 to 7,160 ppm and boron from 0 to 21,500 ppm. Mineralization generally increases with depth and is concentrated in the lower half of this unit. This zone, with an average thickness of 385 meters, is referred to as the Lower Zone of mineralization.
• Lower Sandstones display low to moderate lithium and boron values, ranging from 50 to 2,000 ppm lithium and 50 to 1,000 ppm boron.
• Volcanic Basement rocks show low lithium and boron values. The top 12 meters of basement intercepted within the project area average 57 ppm lithium and 10 ppm boron.
The exact mineralogical form of lithium remains uncertain; however, mineralization is clearly concentrated in the claystone units. Lithium and boron concentrations correlate with finer grain sizes, particularly in the >10 µm fraction of the claystones. No discrete lithium-bearing minerals have been identified in petrographic studies to date. However, lithium is likely hosted within smectite and illite clays or may occur as lithium salts precipitated in fine-grained clay, silt, and sand pore spaces.
Boron mineralization is spatially associated with lithium but appears to be primarily hosted in searlesite, a sodium borosilicate mineral (NaBSi2O5(OH)2), as confirmed by petrographic analysis.
The XRD results show that Lithium in the Bonnie Claire system appears to be associated with multiple mineral hosts, depending on lithology and stratigraphic unit:
• Muscovite (22 to 26%) is consistently present in high-grade green claystone intervals, suggesting it is the primary lithium host via structural substitution in its octahedral sites.
• Analcime (2 to 10%), present in deeper intervals of green claystone, may represent a secondary lithium host as part of the zeolite group, potentially storing Li in its framework or as exchangeable cations.
• Zeolites and heulandite dominate the low-grade sandstone interval, which lacks muscovite and shows significantly lower Li content, indicating these minerals may have a limited capacity to host lithium or reflect dilution by detrital phases.
• Trace halite and calcite suggest possible evaporitic or diagenetic environments, which may influence Li mobility or lead to minor Li-salt formation under closed-basin conditions.