Geophysical Breakthrough: Casiterita Property Reveals Major Subsurface Intrusive Body Beneath Bolivia's Iska Iska Complex

Exploration efforts in southern Bolivia have yielded significant findings through integrated geophysical analysis. Eloro Resources Ltd. (TSX-V: ELO; OTCQX: ELRRF; FSE: P2QM) has completed comprehensive modeling of ground magnetic data and an inaugural Induced Polarization/Resistivity (IP/Res) survey on the Casiterita property, which adjoins the Iska Iska Silver-Tin Polymetallic project to the southwest. Combined with earlier geophysical work conducted on Iska Iska, these investigations have substantially clarified the subsurface geological architecture and unveiled promising new drilling targets on the optioned Casiterita property.

Extensive Intrusive Body Identified Across Both Properties

Magnetic analytical modeling indicates the presence of a substantial subsurface intrusive body measuring approximately 5 kilometers in length by 3 kilometers in width, extending across both the Iska Iska and Casiterita properties. A three-dimensional inverse magnetic model incorporating newly acquired Casiterita data demonstrates remarkable geological continuity, tracking the magnetic anomaly from the Santa Barbara Deposit area southward to Casiterita across a distance of 4.5 kilometers.

The longitudinal section reveals a complex structural architecture: late east-west striking faults progressively displace the magnetic body southward before it is uplifted again within a graben structure positioned immediately south of Porco-Mina 1-2. This structural configuration suggests that the southerly magnetic anomalies may represent a significant tin porphyry deposit, supported by drilling evidence from the southwest side of Santa Barbara, where deep intersections consistently contain tin mineralization.

Conductivity Survey Extends Understanding of Mineralization

Five east-west lines of pole-dipole IP/Res surveying were deployed across the southern boundary between Iska Iska and Casiterita, employing eight 50-meter dipoles that achieved depths of investigation approaching 200 meters. The resulting three-dimensional conductivity model reveals continuity between the conductive zone mapped on Iska Iska and a newly identified strong conductivity anomaly on Casiterita extending approximately 1 kilometer along strike across all five survey lines.

Dr. Chris Hale, P.Geo., Chief Geophysicist at Eloro, observed: “The conductor detected through the Casiterita IP/Resistivity survey is exceptional both in magnitude and spatial extent. The coincident conductive and magnetic anomalies suggest pyrrhotite may generate both geophysical signatures. The deeply positioned sulphide zone previously intersected in Iska Iska boreholes now appears to continue southward into Casiterita, where lower surface elevation permits detection nearer to the surface—a critical indicator, as such sulphide halos frequently characterize Bolivian tin porphyry deposits.”

Regional Geological Context and Deposit Analogs

The Iska Iska complex represents a multi-stage porphyry system overprinted by high to intermediate-sulphidation epithermal mineralization, situated within the extensive Bolivian porphyry tin belt. This metallogenic trend extends along a northwest-southeast structural corridor for approximately 100 kilometers, encompassing the Tasna, Chorolque, Tatasi-Portugalete, and Chocaya-Animas-Siete Suyos mining districts—all exhibiting classic Bolivian silver-tin polymetallic deposit characteristics.

Dr. Osvaldo Arce, P.Geo., General Manager of Eloro’s Bolivian subsidiary Minera Tupiza, S.R.L., noted that the Iska Iska system is centered on granodioritic porphyry stocks postdated by dacitic volcanic domes and associated with large magmatic-hydrothermal breccias. The deposit exhibits well-developed alteration-mineralization zoning: silicic and argillic alteration overprinting quartz-tourmaline and sericite assemblages that grade outward to propylitic alteration. Mineralization was generated through widespread hydrothermal activity occurring approximately 14 to 12 million years ago, with profound telescoping of epithermal overprinting on porphyry alteration and mineralization evidenced by veins, fracture fillings, and replacement textures.

Dr. Arce elaborated: “Iska Iska represents a geological synthesis, incorporating the highest-level mineralized phreatic breccias down to much deeper tin porphyry systems. Compared with regional analogs including Tatasi-Portugalete and Chocaya-Animas-Siete Suyos, Iska Iska is geologically unique. Exceptional preservation of the system resulted from the erosionally resistant Ordovician quartz sandstone basement rocks and silicification associated with porphyry-epithermal mineralization. Historical exploration failed to delineate the deposit because intense oxidation stripped metals near surface.”

Casiterita Property: Historic Tin Production and Modern Discovery

Historical records document artisanal tin mining operations on Casiterita during the 1960s, where high-grade tin veins hosted in intrusive dacite were worked. Between 1962 and 1964, production reportedly reached 69.85 tonnes grading 50.60% Sn according to Bolivia’s Departamento Nacional de Geología. Recent magnetic surveys conducted by Eloro have mapped an extensive, near-surface magnetic intrusive body on Casiterita immediately southwest of Iska Iska. This intrusive hosts the previously exploited high-grade tin mineralization and is interpreted as the continuation of the deeper porphyry tin intrusion projected to underlie the epithermal Ag-Sn-Zn-Pb mineralization at Iska Iska.

The Porco adit, situated near the northeast boundary of the magnetic anomaly, yielded channel sampling averaging 103 meters grading 521 g silver equivalent per tonne (including 117 g Ag/t, 1.44 g Au/t, 0.54% Cu, and 0.66% Sn) within altered basement sediments. These results attest to the strength and high-grade character of the mineralized system.

Operational Plans and Exploration Program

Dr. Bill Pearson, P.Geo., Executive Vice President of Exploration at Eloro, commented: “Geophysical methods have proven instrumental in advancing both Iska Iska and Casiterita exploration. Our planned initiatives include additional borehole IP/Res and surface IP/Res lines in the Porco area north of the magnetic anomaly to establish continuity with the major conductive zone further south. Diamond drilling commenced in February 2023 within the Porco and Mina 1-2 areas, with operations transitioning to Casiterita to test the major tin porphyry target following road rehabilitation and drill pad preparation.”

The geophysical surveys were executed by MES Geophysics utilizing Eloro’s GEM Systems GSM-19W Overhauser magnetometers for magnetic acquisition and an ELREC-Pro 10-channel receiver with GDD 3600-watt transmitter for IP/Res measurements. Dr. Chris Hale, P.Geo., and Mr. John Gilliatt, P.Geo., of Intelligent Exploration designed the survey protocols and prepared interpretive maps. Data processing and quality assurance were overseen by Mr. Rob McKeown, P.Geo., of MES Geophysics. All mentioned professionals qualify as Qualified Persons under NI 43-101 standards.

Project Overview and Corporate Position

The Iska Iska Silver-Tin Polymetallic project is a road-accessible, royalty-free property located 48 kilometers north of Tupiza city in Sud Chichas Province, Potosi Department, southern Bolivia. Eloro, through its Bolivian subsidiary, has secured an option to earn 100% interest. The property encompasses a Miocene possibly collapsed/resurgent caldera measuring 1.6 by 1.8 kilometers with a vertical extent exceeding 1 kilometer, emplaced on Ordovician basement rocks hosting major breccia pipes and hydrothermal bodies. Mineralization age correlates with Cerro Rico de Potosí and other regional deposits.

Eloro Resources operates as an exploration and mine development company maintaining a portfolio of gold and base-metal properties across Bolivia, Peru, and Quebec. In addition to Iska Iska, the company holds an 82% interest in the La Victoria Gold/Silver Project in Peru’s North-Central Mineral Belt, positioned approximately 50 kilometers south of Barrick’s Lagunas Norte and Pan American Silver’s La Arena operations.