Bluestone Resources Inc. (TSX-V: BSR) (OTCQB: BBSRF) is pleased to report assay results from its 2021 infill drill campaign at Cerro Blanco that focused on the Salinas silica cap, a layer of near-surface, low-grade disseminated mineralization some 100-150 meters thick that overlies the high-grade quartz-adularia vein swarms. This recent drilling was undertaken to support the upcoming feasibility study for a surface mining scenario.
Results include the following drilled intercepts:
Jack Lundin, President and CEO, commented, “The Salinas unit forms the top of the Cerro Blanco deposit and the recent pivot to surface mining now allows this upper layer to be mined and processed during the preliminary years of mine life. This supplementary drill program was initiated and successfully completed on schedule and will contribute to a new resource estimation currently underway. The Salinas accounts for about one-fifth of the current resource, and these encouraging results will lead to the definition of additional ounces and improved detail in the mine plan.”
As previous drill campaigns focused on the high-grade veins within the underlying Mita unit, the primary objective of the drill program was to increase the density of drillholes within the Salinas unit, define extensions to the mineralization, and potentially upgrade the current mineral resource to a higher classification.
The new estimate is expected to improve the current resource classification for the Cerro Blanco surface operation and will form the basis of the open pit reserves calculation as part of the feasibility study.
A total of 52 holes are reported, comprising a total of 6,724 meters, including assays from the recent sampling of four holes drilled in late 2020.
|HOLE ID||FROM (m)||TO (m)||CORE
|Au g/t||Ag g/t|
|Intervals in bold are cited in the text of the news release. *Grade top cut of 20 g/t was applied, un-cut interval assays 150.1m @ 1.8 g/t Au, 5.9 g/t Ag.|
A full table of results, accompanied by drill hole locations, sections, and core photos can be accessed by clicking HERE.
The Salinas unit, the focus of the 2021 drilling, is typical of a silica cap associated with low-sulphidation epithermal deposits, consisting of silicified conglomerates and sandstones, with sinter horizons, breccias and rhyolite flows that overlie high-grade bonanza-type quartz-adularia veins in underlying Mita sediments. Two silica sinter horizons, up to 15 meters thick, represent the former paleosurface of the deposit and attest to the un-eroded, near-complete preservation of the Cerro Blanco epithermal system.
Most of the high-grade veins appear to feather out and discontinue above the Salinas/Mita contact, apart from the south-eastern part of the South Zone, where a series of sub-vertical quartz veins propagate from the underlying Mita sediments into the Salinas polymictic conglomerates and sandstones, which are extensively silicified. Consequently, some of the better grades and thicknesses are observed in this part of the South Zone, e.g., CB21-469 which assayed 140 meters at 1.1 g/t Au from surface. In some drill holes, high-grade veins were intersected at the top of the Mita unit immediately below the contact of the Salinas, e.g., CB21-487 which assayed 30.2 g/t Au and 85 g/t Ag over 7.6 meters.
The drilling has defined extensions and improved the limits of mineralization and will improve the 3D modelling of individual lithologies and understanding of grade distribution within the Salinas unit. This new information will be incorporated into an updated geological model that will form the basis of the ongoing engineering studies.
Quality Analysis and Quality Control
Assay results listed within this release were performed by Inspectorate Laboratories a division of Bureau Veritas, which are ISO 17025 accredited laboratories. Logging and sampling are undertaken on site at Cerro Blanco by Company personnel under a QA/QC protocol developed by Bluestone. Samples are transported in security-sealed bags to Inspectorate Labs in Managua, Nicaragua, for sample preparation. Sample pulps are then shipped to Inspectorate in Hermosillo, Mexico, and assayed using industry-standard assay techniques for gold and silver. Gold and silver are analyzed by a 30-gram charge with atomic absorption and/or gravimetric finish for values exceeding 5 g/t Au and 100 g/t Ag. Analytical accuracy and precision are monitored by the analysis of reagent blanks, reference material, and replicate samples. Quality control is further assured by Bluestone’s QA/QC program, which involves the insertion of blind certified reference materials (standards) and field duplicates into the sample stream to independently assess analytical precision and accuracy of each batch of samples as they are received from the laboratory. A selection of samples is submitted to ALS Chemex Laboratories in Vancouver for check analysis and additional quality control.
David Cass, P.Geo., Vice President Exploration, is the designated Qualified Person for this news release within the meaning of National Instrument 43-101 and has reviewed and verified that the scientific and technical information set out above in this news release is accurate and therefore approves this written disclosure of the technical information.
About Bluestone Resources
The Cerro Blanco Gold Project is an advanced stage near surface development project. A PEA on the project highlighted an asset capable of producing over 300 koz/yr with an average annual production of 231 koz/yr at all-in sustaining costs of ~$642/oz (as defined per World Gold Council guidelines, less corporate general and administration costs) over an initial 11-year mine life.
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