Project AspectProject IconProject Aspect Description
SUPPLYING CRITICAL MINERALSCritical MineralsRhyolite Ridge produces battery components that will power 50 million EVs and strengthen domestic supply chains
CREATING NEVADA JOBSNevada Jobs400-500 during construction and 250-300 jobs during operations
GENERATING LOCAL AND STATE IMPACT Public Revenue ImpactProject will generate $15-25 million during construction and $13-31.5 annually once operational
LOW WATER USAGELow Water UsageApproximately 3,550 acre-ft/year usage of water, a similar usage to seven irrigation pivots and 840 acres
ROAD IMPROVEMENTSRoad ImprovementsCommitted to maintain and improve road from Highway 264 to facility
REDUCING EMISSIONS Low EmissionsCarbon-free energy production and limited greenhouse gas emissions
LIMITING OUR FOOTPRINTSmall FootprintNo evaporation ponds, no tailing dam. Approximately 931-acre footprint

*Applied Analysis Economic Impact Study, April 2020, Low-High Case Range


The Rhyolite Ridge Lithium-Boron Project is located in Esmeralda County, Nevada, on public land administered by the U.S. Department of Interior’s Bureau of Land Management (BLM) within the Silver Peak Range.

Rhyolite Ridge Location

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Project Location

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Average Commute Times from RR

Rhyolite Ridge is approximately 14 miles northeast from Dyer, Nevada (nearest town); 65 miles southwest of Tonopah, Nevada (closest city); 215 miles from Reno (third largest city in Nevada); and 255 miles from Las Vegas (largest city in Nevada).  Average commute times to Rhyolite Ridge from nearby communities are noted in the image to the left.  Surface elevations at the project site range from 5,535 to 6,010 feet (1,687 to 1,832 meters) above sea level

Community Engagement

Ioneer is committed to making a positive impact on the global environment and that starts with the support of the local community. We have solicited feedback and provided updates to the community on a regular basis as the project has progressed. We also have worked closely with regulators regarding the socio-economic studies required for permitting projects on land administered by the BLM.

In April 2020, Applied Analysis issued an economic impact study related to the Rhyolite Ridge Project. Key findings from the study are below.


  • Construction of the Rhyolite Ridge Project is expected to take two years. The combined value of all spending as a result of the project’s construction (i.e., economic output) is estimated to range from $68 million to $217 million.
  • Given direct and indirect economic benefits of the project, for every dollar spent in the local economy on the development of the Project, a total of $1.99 in economic activity benefits the community as a whole.
  • Over the expected construction period, using a median case scenario Applied Analysis calculates the creation of 946 person-years of employment, or about 473 construction jobs per year. This will result in over $60 million in wages and salaries, and an overall economic output of over $130 million.


  • Once the Rhyolite Ridge project is operational, the same study projects that Rhyolite Ridge will directly employ 284 persons per year, for a total of nearly $40 million dollars in annual wages (average total compensation of $140,727 per job).
  • Additionally, nearly 681 indirect jobs are projected to be supported through purchases of supplies for the project, generating an additional $40.9 million in annual wages.
  • Further, local spending from both direct and indirect employees is expected to support an additional 381 jobs per-year across the region.


  • During the construction phase of Rhyolite Ridge, the Applied Analysis report projects that the Project will contribute approximately $22.5 million in sales and use taxes to benefit local and state governments using its median case assumptions.
  • Once in operation, the Project will generate approximately $22 million annually in fiscal revenue for state and local governments through 1) Nevada net proceeds of minerals taxes, 2) sales and use taxes, 3) property taxes, 4) modified business taxes, 5) commerce taxes and 6) regulatory fees. This estimate is also calculated by Applied Analysis using its median case assumptions.


  • The investment by Ioneer in the local community goes beyond jobs and broader economic impact: we have been, and plan to continue to be an active participant in the community by supporting local causes. This includes the annual Ioneer Sustainable World Scholarship – which is awarded to Tonopah High School seniors pursuing higher education in Engineering, Science and/or Mining.
  • Total charitable investments in the community are expected to range between $100,000 and $250,000 during operations.

Regional Geology

The Rhyolite Ridge Project site is situated in the Silver Peak Range, part of the larger geo-physiographic Basin and Range Province of western Nevada. Horst and graben normal faulting is the dominant characteristic of the Basin and Range Province, which is believed to have occurred in conjunction with large-scale deformation due to lateral shear stress. This is evidenced in the disruption of large-scale topographic features throughout the area. The project area sits within the Walker Lane Fault System, a northwest trending belt of right-lateral strike slip faults.

Rhyolite Ridge is a geologically unique lithium-boron deposit that occurs within lacustrine sedimentary rocks of the South Basin, peripheral to the Silver Peak Caldera. The South Basin within the project boundaries measures 4 miles by 1 mile and covers an area of just under 2,000 acres.

The regional geology is characterized by relatively young Tertiary volcanic rocks thought to be extruded from the Silver Peak Caldera, which date to approximately 6.1 million to 4.8 million years old. The northern edge of the Silver Peak Caldera is exposed approximately 2 miles to the south of the South Basin area and is roughly 4 miles by 8 miles in size. The Tertiary rocks are characterized by a series of interlayered sedimentary and volcanic rocks, which were deposited throughout west-central Nevada. These rocks unconformably overlie folded and faulted metasedimentary basement rocks that range from the Precambrian through Paleozoic periods.

Rhyolite Ridge is one of only two major lithium-boron deposits globally and the only known deposit associated with the boron mineral searlesite. This mineralization style is different to the brine and pegmatite deposits that are the source of nearly all the lithium produced today and is also unlike lithium-claystone deposits found in the region.

The laterally continuous sediments of Cave Spring form distinctive units and are found outcropping at surface as well as at depths of up to 1000 feet. Interbeds of siltstones, claystones and carbonate units characterize the formation and pumice-rich volcano-sedimentary units called gritstones form pervasive marker beds.

The 6 million-year-old basement rocks – Rhyolite Ridge Tuff and Argentite Canyon Latite – represent the early stages of volcanic activity for the Silver Peak Caldera. The caldera, with activity spanning 1 million years, injected volcanic glass, rhyolite and ash into a spring-fed closed basin, depositing the Cave Spring Formation.

The highly competent 65-foot-thick ore zone, formed by diagenesis of volcanic sediments deposited in an alkaline lake, is characterized by very fine boron-rich searlesite crystals (up to 30,000 parts per million (ppm) boron) and lithium in illite-smectite layers (about 1,500-2,500 ppm lithium).


Mining Extraction Map

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The overall site plan for the Rhyolite Ridge Project is shown to the left. The compact project site extends from the mine quarry in the west to the processing facilities and spent ore storage facility in the east. The processing facilities are approximately 1.8 miles northwest of the quarry and 1 mile north of the spent ore storage facility.

The mining operations will consist of a conventional drill-and-blast, load-and-haul operation. Ore will be trucked from the mine quarry to the nearby ore processing plant over a new heavy duty haul road.


Ioneer expended considerable effort to develop a safe and economically viable Project while avoiding
and/or minimizing potential impacts to environmentally sensitive areas.

Regarding the current permitting actions, a quarry will be developed in the southwestern part of the ore body to supply the processing plant for the first 4.5 years of the Project. In this area, lithium grades are 15% higher than the average grade for the deposit and the ore is more exposed at surface. The quarry designs were completed based on the selected optimized quarry shell. The Plan of Operations mine footprint is approximately 931 acres.

Ioneer will capitalize on current mining advances to enhance project performance including haul truck automation. In February, 2021, Ioneer announced the completion of a joint automation study conducted with Caterpillar, the world’s largest manufacturer of construction and mining equipment, and the Cat dealer for Nevada, Cashman Equipment Company. The study targets the early introduction of Cat® Command for hauling, Autonomous Haul System (AHS) at Rhyolite Ridge for improved safety, equipment utilization and site productivity. To date, Cat autonomous mining trucks have safely hauled more than 2 billion tons of material worldwide, driving over 42 million miles.

With the study complete, Rhyolite Ridge appears to be a very favorable candidate for AHS and Ioneer and Caterpillar have signed a memorandum of understanding to move the initiative forward.


Low-carbon Emissions Strategy

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The lithium and boron that will be produced from Rhyolite Ridge will be done with an emphasis on limiting water usage, on-site co-generation of power and state of the art emission controls.

The process plant design is shown to the left and described further below.

Lithium and boron can be readily leached from the Rhyolite Ridge host rock using dilute sulphuric acid, which differentiates Rhyolite Ridge from other sediment-hosted lithium deposits. This is due to the low-clay, low-carbonate and high-searlesite (boron) content of the rock. Leaching with be done in vats to allow for temperature control and resulting in maximized recoveries and recycling of materials.

Due to our ability to process the lithium and boron in this way, there will be no evaporation ponds or tailings dam at Rhyolite Ridge – leading to a comparatively small quarry footprint. Rhyolite Ridge’s processing facilities will include a sulfuric acid plant and steam turbine. This will allow the Company to produce sufficient electricity to power its entire operation, meaning zero reliance on the Nevada electrical grid and minimal use of fossil fuels to produce needed electricity. Electricity generated in this manner produces minimal CO2 emissions, minimal air pollutants, and is considered green cogenerated power.

Ioneer and its partners have spent thousands of hours of bench and pilot plant test work related to the Project’s process flowsheet. Based on these efforts, the Project’s engineering team designed the facilities using known and commercially proven technology to accommodate the unique Rhyolite Ridge ore. The primary reagents used in lithium and boric acid production are 1) liquid sulphur, 2) soda ash, 3) lime and 4) fuel.

Key process operations are described below:


The vat leaching process uses a series of 7 vats where crushed ore is sequentially leached for 3 days with diluted sulphuric acid. The vats operate in a counter-current configuration, made possible by the unique Rhyolite Ridge ore particles remaining largely intact and free-draining during the leach process. Counter-current leaching minimizes the overall leaching time and acid consumption. The spent ore undergoes a displacement wash to remove valuable interstitial lithium and boron in solution. The spent ore is free draining, allowing the vat to be emptied of solution producing a residue material that is suitable for dry stacking. High lithium and boron recoveries in leaching are consistently achieved at low to moderate temperatures (60°C) and moderate free-acidity levels.


Crystallization of boric acid is achieved by cooling the vat leach solution (referred to as PLS – pregnant leach solution). Since the PLS is close to saturation in boric acid, the cooling effect in the crystallizer produces boric acid crystals. The boric acid crystals are separated using centrifuges and then undergo a second-stage recrystallization for purification. Most of the boric acid is recovered with minimal contamination from sulphate salts.


The main evaporation and crystallization circuit is designed to concentrate lithium and remove sulphate salts and other impurities. The solution (mother liquor) from the boric acid crystallization undergoes impurity removal of aluminum and other elements and is then pumped to a 4-stage evaporator circuit to remove 70% contained water and concentrate the lithium. Water vapor from the evaporators is condensed and reused throughout the process. This evaporation and crystallization process is critical to the concentration of the lithium to a high-level suitable for the lithium carbonate circuit.


The lithium carbonate circuit is designed to produce technical-grade lithium carbonate from the lithium brine mother liquor. Lithium carbonate is precipitated from the mother liquor using soda ash. The precipitated lithium carbonate is filtered, washed, and dried. The lithium carbonate produced can be sold as a technical-grade (99.0%) product or converted into lithium hydroxide (99.5%). For the first 3 years, we currently expect that lithium carbonate will be sold as technical-grade.


A 3,858 tons per day sulphuric acid plant will produce commercial-grade (98.5%) sulphuric acid for vat leaching the ore; steam to drive the evaporation and crystallization steps; and electricity to drive the entire process. The plant will generate 35 MW of electricity – sufficient to run the entire facility and will be separate from the Nevada state power grid. The selection of the technology for the large sulphuric acid plant is based on a proven operating design and specialty technology provider (MECS-DuPont). The acid plant is a double conversion-double absorption system that has proven to be reliable and predictable. It includes a tail gas scrubber system that results in ultra-low emissions (12 ppm SO2 and 15 ppm NOx).


The Rhyolite Ridge process flowsheet demonstrates a strong synergy for the installation of an onsite lithium hydroxide circuit. Installation of the circuit is currently planned for year 3 of operations, allowing the main plant to be operating smoothly before the addition. The conversion of Rhyolite Ridge technical-grade lithium carbonate to battery-grade lithium hydroxide will be achieved by the liming method and further utilize the electricity generated by the sulphuric acid plant.


Ioneer is committed to providing a safe, injury-free work site while protecting the environment and surrounding communities.

A site health, safety, environmental (HSE) and security program will be developed for the construction phase and transitioned to the operations phase. The program will meet or exceed mandatory codes, acts, and regulatory requirements of MSHA of the U.S. Department of Labor. The HSE program will include safety requirements addressing hazardous processes, hazardous materials and equipment, fire suppression equipment, safe work permit requirements, emergency procedures, safety training requirements, incident reporting, and medical services support.

The message that safety is a core value will be communicated to all levels of the project’s organization and workforce. The HSE plan will describe the project’s core values and policy for complying with all relevant HSE commitments, laws, and regulations. Training for employees will include a comprehensive overview of expectations for safe execution of work activities on the project. This training will include instructions on how all project employees, contractors, and other personnel are to perform their duties and comply with MSHA regulations.