Summary:
Deposit Type
Bonnie Claire is a lithium-boron claystone deposit of the type 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.
Geology and Mineralization
Bonnie Claire is a closed basin near the southwestern margin of the Basin and Range geo-physiographic province of western Nevada. Horst and graben normal faulting is a dominant structural element of the Basin and Range.
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 resulting topography consists of an elongate, flat area of covered quaternary sediments of alluvium and a playa. The alluvial fans in the eastern portions of the Project area are commonly mantled with weathered remnants of rock washed down from the surrounding highlands. The alluvial fans are covered with sporadic shrubs. In most portions of the Project, the playa is completely covered with mud and salt and is frequently referred to as mud flats in this report.
Multiple wetting and drying periods during the Pleistocene resulted in the formation of lacustrine deposits, salt beds, and lithium-bearing brines in the Bonnie Claire basin. Extensive diagenetic alteration of tuffaceous rocks to zeolites and clay minerals has taken place, and anomalously high lithium concentrations accompany the alteration.
Two distinct sedimentary horizons contain potentially economic mineralization at Bonnie Claire. Both are hosted by claystones, and form horizontal to gently-dipping sheets that display great lateral continuity, separated by a thick layer of barren sandstone horizon.
• Upper Claystones display moderate lithium and boron mineralization, ranging from 55 to 2,210 ppm lithium, and variable 5 to 8,900 ppm boron. This is referred to as the Upper Zone of mineralization at Bonnie Claire.
• Lower Claystones display variable to very high lithium and boron mineralization, ranging from 133 to 7,160 ppm lithium and 0 to 21,500 ppm boron. Mineralization increases with depth and is concentrated in the lower half of this unit. This is referred to as the Lower Zone of mineralization at Bonnie Claire.
The exact nature of the lithium mineralization is unclear, but mineralization is concentrated in the fine claystone (>10 micron) sediments. No discrete lithium mineral species has been identified by petrographic analysis so far, but it is likely to form part of the clay minerals that occur with the claystones, or as lithium salts deposited in the fine grain pore space. XRD analyses conducted in 2022 and 2024 support this interpretation, identifying lithium-associated phases such as illite-smectite, smectite clays, analcime (zeolite), and evaporite minerals including halite and calcite, all consistent with lithium being structurally bound in clays or precipitated in pore spaces.
Boron mineralization spatially correlates with lithium mineralization, and XRD analysis has identified a significant component of searlesite, a sodium borosilicate mineral with the chemical formula NaBSi2O5(OH)2, which is most likely the dominant boron-bearing phase.