The mining company Apollo Silver Corp. has taken a decisive step in the planned development of the Calico Project by engaging SLR Consulting (Canada) Ltd. to direct a preliminary economic assessment (PEA). Announced in a March 18, 2026 release, the appointment sets the stage for an integrated technical review that will consider multiple mining and processing scenarios for the deposit in San Bernardino County, California. Alongside the PEA, Apollo Silver is advancing complementary programs — notably metallurgical and geotechnical studies — designed to provide the engineering detail required for later development stages.
This study phase is intended to move the project from resource definition toward an engineering and economic framework that can be refined into pre-feasibility and feasibility work. The PEA will assemble geological models, recovery expectations and capital/operating cost estimates while SLR provides oversight and validation. Apollo Silver also intends to use the results to shape future drilling and processing test priorities. Management describes the PEA and parallel technical programs as central to determining whether Calico can transition into a permitted and funded operation.
Table of Contents:
Technical program: geotechnical and metallurgical focus
SLR’s role includes both advisory and supervisory responsibilities for ground investigations and laboratory test work. The geotechnical component will cover site investigation planning, technical guidance for logging and laboratory analyses, and a desktop geotechnical gap analysis to identify missing data. In addition, SLR will provide QA/QC oversight of third-party fieldwork to ensure that foundations, pit wall designs and other mine infrastructure considerations are informed by reliable rock and soil data. These inputs are critical for developing a safe, cost-effective mine plan.
Metallurgical test design and process evaluation
On the metallurgical side, SLR will support the design and interpretation of test programs focused on the Waterloo deposit, including sample selection, laboratory testing plans and recovery estimation. The metallurgical program aims to define mineral recoveries and help optimize a processing flowsheet that could be used in subsequent studies. Previously collected samples are being reassessed for additional testing. Results from this work are expected to feed directly into the PEA and influence projected recoveries and capital expenditure estimates.
Airborne geophysics and exploration targeting
To supplement the technical studies, Apollo Silver contracted Precision GeoSurveys US Inc. to complete a high-resolution airborne magnetic and radiometric survey over the Waterloo and Mule properties. The program covered approximately 632-line km with 50-meter line spacing, generating dense geophysical coverage to aid geological interpretation. The airborne data were designed to highlight lithologic and structural signatures associated with known mineralization and to search for similar patterns elsewhere across the land package, with the goal of defining and prioritizing drill targets for future campaigns.
Survey aims and next steps
The survey set out to compare radiometric signatures at Waterloo to those at Mule and to determine whether surface expressions of the mineralized system recur regionally. Interpreting magnetic anomalies alongside radiometric maps will refine geological models and support more focused surface mapping and drilling. Apollo Silver plans to integrate these geophysical results with field mapping and the ongoing technical studies to improve drill targeting and reduce exploration risk.
Project scale, resources and strategic value
The Calico Project spans roughly 8,419 acres across three properties (Langtry, Waterloo and Mule) in the historic Calico Silver Mining District, approximately nine miles northeast of Barstow, California. The 2026 mineral resource estimate identifies a substantial silver endowment: 125 million ounces in the Measured and Indicated category within 55 million tonnes grading 71 g/t silver, and 58 million ounces in the Inferred category within 25 million tonnes grading 71 g/t silver. The deposit also contains notable critical mineral credits in barite and zinc, enhancing its potential strategic importance to domestic supply chains.
Resource reporting referenced Stantec’s NI 43-101 technical work and a technical report with an effective date of June 30, 2026, as noted in company disclosures dated September 4 and October 16, 2026. The presence of multi-commodity potential — silver with barite and zinc by-products — can materially affect project economics and processing choices. Apollo Silver emphasizes that the majority of mineral resources lie on private land with established mining rights, which can shorten some permitting pathways compared with wholly public-land projects.
Qualified technical review of the material in Apollo Silver communications was provided by Isabelle Lépine, M.Sc., P.Geo., a registered professional geologist and the company’s director, mineral resources, acting as the qualified person under NI 43-101. Apollo Silver’s management expects the PEA and supporting programs to advance engineering understanding and to inform future exploration and development decisions. Interested parties can find further company information at www.apollosilver.com and may contact the corporate office for additional details.
