The Santo Tomás Project hosts a porphyry copper deposit comprised of fracture and disseminated Cu and Mo sulphides with significant Au and Ag credits. The Project lies within the Laramide Belt, a NW-SE trending copper belt extending from southwestern USA into southern Mexico that includes numerous world-class copper deposits, including the Cananea district, which hosts one of the largest copper deposits in the world.
Mineralization at Santo Tomás is mapped on surface and drill tested along a strike length of 4 km. The Project was initially defined by exploration from 1968 to 1994. During that time, Santo Tomas was tested by 106 diamond and reverse circulation drill holes totaling approximately 30,000 meters. In 1994, at the request of Exall Resources Limited, a resource estimate was conducted by Mintec, Inc. of Tucson, Arizona. In addition, metallurgical testing was conducted by Mountain States Research and Development, Inc. (“MSRDI”) and, in reliance on information generated by these studies, a Prefeasibility Study was conducted by Bateman Engineering Inc. of Tucson, Arizona which yielded a positive result. Bateman completed this study, titled “Santo Tomas Project, Sinaloa, Mexico, Pre-Feasibility Study”, in July 1994, using only measured and indicated mineral resource estimates* in its work. This report contemplated mining rates of up to 120,000 TPD, producing up to 300 million pounds of copper per year, plus quantities of gold and silver, in a high-quality concentrate. Conventional open pit mining, hauling and ore beneficiation technology are all addressed in the study, with no design risks identified or implied.
While the economic assessment by Bateman contains favourable metallurgical test results and engineering designs that remain broadly acceptable today, the Company considers these historical studies and associated mineral resource estimates to be conceptual in nature only, until confirmed by current technical programs.
In 2017, Oroco initiated a comprehensive geological mapping program of the entire project area as a part of its project evaluation work. This evaluation was generated using all available exploration data from historic diamond drilling, rotary and reverse circulation holes from the 1968 – 1994 exploration programs together with their associated reports.
In 2019, the Company began rehabilitating access to the property and the construction of camp and support facilities on site. In September of 2020, the company commenced a full 3-D resistivity and induced polarization (IP) survey. This survey is targeted to cover an area of approximately 10 square kilometers of the property, encompassing the mineralized South Zone, North Zone and Brasiles Zone at Santo Tomas. With the results from that survey providing a strong correlation with the historical data, the Company is now using those survey results as a guide for its current drilling program.
Location and Infrastructure
The Santo Tomás Project is located in the municipality of Choix, on the south bank of the Fuerte River, in the western Sierra Madre mountain range. The project straddles the border between the States of Sinaloa and Chihuahua. Proximal infrastructure includes the deep-water port of Topolobampo, located 175km to the south-west, connected by sealed roads, a rail line, high voltage power supply, and a high-pressure gas pipeline, all within 20km or less of Santo Tomás. The region hosts numerous mining operations and has a strong regional mining culture and a highly supportive local community.
*The resource estimates are a Historical Estimate as defined in NI 43-101 of the Canadian Securities Administration. While the Historical Estimate is considered reliable and relevant as they employ reliable estimate practice and utilized all available drilling information in the preparation of the Historical Estimates, a qualified person has not done sufficient work to classify the Historical Estimates as current mineral resources or mineral reserves and the Company is not treating them as current mineral resources or mineral reserves. For the Historical Estimates to be reported as a current resource estimates, resampling and assay of historical drill samples, twinning of historical drill holes, and a new program of regularly spaced drilling are required, and for these reasons the Company has no intention of reporting the Historical Estimate as a current resource estimate.
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These historical resource estimate models are based upon historical resource estimates prepared by John Thornton in 2011. While, in the opinion of Dane A. Bridge, author of the revised NI 43-101 standard technical report, Geology, Mineralization and Exploration of the Santo Tomas Cu-(Mo-Au-Ag) Porphyry Deposit, Sinaloa, Mexico dated April 21, 2020 (the “Report”), reliable estimation practices were used, in order to upgrade or verify the historical estimations, resampling and assay of historical drill samples, twinning of historical drill holes, and a new program of regularly spaced drilling is required. No qualified person has undertaken sufficient work to classify the current mineral resources or mineral reserves upon which these models are based and the Company is not treating the estimates as current estimates of the mineral resources. The Company gives no assurance that either these models or the historical resource estimates upon which they are based are accurate, and does not undertake any obligation to update the models or to release publicly any update or revisions of the resource estimates except as required by applicable securities law. The reader is cautioned not to rely upon these models or the historical resource estimates upon which they are based.