INITIAL DRILLING AT SANTO TOMAS CONFIRMS GRADESHELL MODEL
Oroco Resource Corp. (TSX-V: OCO, US: ORRCF) (“Oroco” or “the Company”) is pleased to announce the receipt of the assay results from its initial drilling campaign at its Santo Tomas property (the “Property”) in northwestern Mexico. Eight drill holes have been completed to date, all in the North Zone (see Figure 1). An additional two drill holes in the North Zone are completed, pending surveying. A further two drill holes are in progress in the North Zone, and another in the Brasiles Zone. Assays reported herein are for the first three holes (N001 to N003) comprising 2,350m of HQ3 and NQ3 diameter diamond drilling which produced 1,492 assay samples.
The Company is very pleased that the initial drilling results confirms the following:
Copper grades in holes N001 to N003 are comparable to the historical drilling reported on each of the cross-sections drilled to date.
Drilling results in N001 to N003 conform closely to, and confirm the geological conclusions and the 2009 Gradeshell model of Cu > 0.3% (the “2009 Gradeshell Model”) contained in the current Technical Report (‘the “Technical Report”) (Bridge, 2019: See SEDAR, or the Company’s website www.orocoresourcecorp.com/projects/technical-reports/). (see Figures 2, 3 and 4).
Geological logging indicates copper is present as chalcopyrite and bornite dissemination and vein fillings. Pyrite is relatively sparse in the main drill intersections.
Molybdenum, gold and silver are elevated across the width of the North Zone and provide about a 15 to 20% contribution to the copper equivalent grade, without factoring for metallurgical recoveries.
Fracturing, Laramide intrusive dikes, mylonite zones, veining and sulphide mineralization are controlled by faulting co-eval with the formation of the North Zone deposit. The deposit is confirmed in drilling with a strike of N20°E and a dip of 50-55°W, as reported in the Technical Report.
Sulphide mineralization in the main intersections on the North Zone are hosted in strongly potassic-altered volcanic and intrusive rocks with an overprint of phyllic alteration.
The footwall of the North Zone is propylitic-altered andesite volcanic rock with disseminated and vein filling pyrite, explaining the extreme Chargeability High response in the 3D IP survey.
The Santo Tomas Cu-Mo-Au porphyry deposit is an example of the geologic style of Laramide-age porphyry copper deposits in the southwestern United States and northwestern Mexico. Historical Pre-Feasibility Studies, recent 3D modelling of historical drilling, and several new programs of geophysical surveying have defined drill targets, both for confirmation of historical mineral resource estimates and for exploration for additional resources.
The 2021 drill program commenced on the central North Zone mineral deposit to confirm historical drill results and the Company’s geological modelling, and has now spanned 500 m of strike length on the North Zone. Historical drilling spanning 1968 to 1994 was primarily vertical and unsuited to defining the full width and depth of the North Zone. The 2021 program is based on angled drill holes oriented perpendicular to the re-modelled strike and dip of the deposit and is the first program that features drill holes that pass from the hanging wall of the North Zone deposit into the footwall and which also features a full suite of assay information that includes copper, molybdenum, gold and silver.
Table 1 contains the most significant intervals in drill holes N001 to N003. Core intervals in this disclosure are within 10% of the estimated true thickness. The Copper Equivalent (%) grade is presented for geological comparisons only within this program and was calculated based on the three-year average of commodity prices with no factoring for metallurgical recoveries, which are not yet known. Silver is noted in Table 1 but not included in the copper equivalent grade calculation. The attached cross-sections depict all core intervals in N001 to N003 exceeding 10m core length of Cu > 0.10%.
Table 1: Significant Assay Intervals in the Santo Tomas 2021 Program, DDH N001 to N003.
Drill Hole No. From
(m) To
(m) Length
(m) Cu % Mo % Au g/t Ag g/t CuEq %
N001 310.0 565.0 255.0 0.39 0.010 0.045 2.20 0.46
“ 571.0 620.0 49.0 0.17 0.003 0.007 1.31 0.18
N002 349.9 630.0 280.1 0.38 0.012 0.025 2.85 0.44
N003 295.0 306.8 11.8 0.31 0.009 0.014 2.85 0.36
315.3 333.0 17.7 0.33 0.008 0.017 1.49 0.37
“ 339.0 364.5 25.5 0.29 0.015 0.020 2.81 0.36
“ 370.0 384.3 14.3 0.50 0.008 0.026 3.33 0.56
“ 390.0 597.7 207.7 0.39 0.014 0.019 2.81 0.45
“ 601.8 678.0 76.2 0.18 0.002 0.007 2.53 0.20
Cu Equivalent (CuEq) % = Cu % + (Mo %*3.75) + (Au ppm*0.752) The commodity prices (3-year Average) used are
in $US: Cu $3.20 /lb, Mo $12.00 /lb, and Au $1, 650.00 /troy oz. Ag was not used.
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