On April 7th, 2026 Prismo Metals announced the successful completion of its Phase I diamond drilling campaign at the Silver King project in the Pioneer Mining District near Superior, Arizona. The program comprised eight holes totaling 1,272 metres of core and was designed to validate historic records and the Company’s three-dimensional geological model of the underground workings. Silver King, discovered in 1875, is a notable historic producer that yielded nearly 6 million ounces of silver at historical grades reportedly up to 61 oz/t, and the property lies just 3.4 km from the main shaft of the Resolution Copper project.
The shallow drilling focused on the previously mined pipe-like zone while a single deep test, SK-26-07, targeted the down-plunge extension beneath old workings. Visual logging and handheld analyses in the upper holes confirmed extensive quartz-barite veining with visible silver-bearing sulfides such as freibergite, stromeyerite, acanthite and native silver. The deep hole reached 1,600 feet (488 m) and intersected a previously unrecognized quartz monzonite intrusive with abundant disseminated pyrite, local chalcopyrite and pyrrhotite, along with zones of strong potassic alteration, suggesting a distinct higher-temperature hydrothermal environment below the epithermal zone.
Table of Contents:
Phase I drilling highlights
The Phase I campaign included eight diamond holes where seven were aimed at the upper portions of the historic Silver King pipe and one deep test targeted the potential down-plunge extension. Every hole intersected the predicted quartz-vein and stockwork system, corroborating historic mine records and the Company’s model. Of particular significance, hole SK-26-07 penetrated a deep intrusive and displayed an assemblage of secondary biotite, K-feldspar selvages and increasing disseminated pyrite downhole. These observations establish a vertical zonation from shallow epithermal silver mineralization into deeper, potentially porphyry-style copper-bearing rocks and expand the target concept beyond a narrowly constrained silver pipe.
Mineralogy and interpretation
Visual and geochemical indicators
Core inspection revealed classic epithermal textures: quartz-barite breccias, vein-stockwork zones and variable sulfide content. Visual identification paired with qualitative handheld XRF indicated the presence of high-silver minerals such as freibergite and acanthite, alongside base metal species including bornite, chalcopyrite, sphalerite and galena. While XRF readings are qualitative and not a substitute for assay results, they reinforced the occurrence of both epithermal silver mineralization near surface and sulfide-bearing mineralization at depth. The co-existence of these assemblages supports a telescoped hydrothermal model where a deeper, higher-temperature system fed later, shallower silver veins.
Evidence for a porphyry transition
Downhole textures and alteration in SK-26-07 are markedly different from the sericite-dominated alteration seen in the upper pipe. The deeper interval from approximately 1,200–1,600 feet intersected potassic alteration — manifested as secondary biotite flakes and pink K-feldspar along quartz veins — together with more abundant disseminated pyrite and scattered chalcopyrite. Such an assemblage is commonly associated with higher-temperature magmatic-hydrothermal systems and is a classic indicator in many productive porphyry copper environments. These features open the possibility that Silver King may link to or be part of a larger porphyry-related system.
Regional context, next steps and team
Silver King sits within a Laramide-age volcanic-intrusive embayment and is adjacent to significant claim blocks including Resolution Copper and those of Ivanhoe Electric. The property’s position in what is colloquially called Arizona’s “elephant country” aligns it with other telescoped systems where shallow epithermal veins overlie porphyry centers, such as the historical correlations between the Silver Queen/Magma relationships. Following Phase I, samples from five holes have been sent to an independent laboratory with additional submissions from SK-26-06 to SK-26-08 expected imminently; final assay results are anticipated in May 2026, roughly 4–6 weeks after drilling completion.
Prismo plans a targeted follow-up program that will include down-hole geophysics, petrographic thin-section analysis, multi-element surface sampling and detailed structure and alteration mapping to refine targets for deeper step-out drilling. The Company has appointed Dr. Linus Keating as a Special Advisor to leverage his porphyry exploration experience, and Dr. Craig Gibson, Ph.D., CPG, has reviewed and approved the technical disclosures as the Qualified Person. The Company also notes that handheld XRF data are qualitative and that historic production figures are not NI 43-101 compliant; further assay confirmation and conventional QA/QC will follow.
