The western portion of the project area is dominated by the uplifted basement rocks of Angel Island which consist of metavolcanic and clastic rocks, and colluvium. The southern and eastern portions are dominated by uplifted, lacustrine sedimentary units of the Esmeralda Formation. Locally the Esmeralda Formation is comprised of fine grained sedimentary and tuffaceous units, with some occasionally pronounced local undulation and minor faulting. The resulting topography consists of elongate, rounded ridges of exposed Esmeralda Formation separated by washes and gullies filled with alluvial cobble, gravel and fine sediment. The ridge tops are commonly mantled weathered fragments of rock (desert pavement) sourced from the surrounding highlands. Cypress provides the following description of the stratigraphic units of the Esmeralda Formation in the project area, which form a laterally and vertically continuous stratigraphic section which underlies the south and eastern portions of the project area.

Elevated lithium concentrations, generally > 600 ppm, are encountered in the local sedimentary units of the Esmeralda Formation from surface to at least 142 meters below surface grade (bsg). The lithium-bearing sediments primarily occur as silica-rich, moderately calcareous, interbedded tuffaceous mudstone, claystone and siltstone. The overall mineralized sedimentary suite is a laterally and vertically extensive, roughly tabular zone with at least two prominent oxidation horizo ........

All materials within the project’s resource area are relatively flat lying soft sediments. The deposit is covered by a thin veneer of alluvial gravels and extends to a depth of 100 to 140 meters.

Mining will be carried out using conventional surface methods. Excavation will use a single Caterpillar 6020B or equivalent shovel (hydraulic excavator configuration) with a 12 m³ bucket capacity. The material is very soft, so drilling and blasting will not be required.

Truck haulage was studied as an alternative. Conveyor transport to the mill is preferred due to reduced traffic and water for dust control. Conveyors should also result in lower operating cost due to the consumption of electric power instead of diesel.

Material at the mining face will be fed directly to a mobile feeder-breaker and then moved out of the pit using a series of jump conveyors. The material will then be transferred to over-land conveyors and transported to a radial stacker and run-of-mine (ROM) stockpile located at the processing plant.

An ultimate pit shell was used to limit the mine plan and was generated using the variable pit slope.

The bench height and width were set at 7.5 meters and 6 meters, respectively, based on operating equipment reach and minimum road width.


Within the ultimate pit shell, 16 pit phases were generated. The first eight of these were used to design a production schedule with uniform mill feed and minimal wa ........

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