Andina Copper posts 232 metres of 0.68% copper, 75 ppm moly from 38 metres at Cobrasco Project, Colombia
Andina Copper Corp. [TSXV: ANDC; FSE: FIR; OTCQB: PMMCF] reported another outstanding drill intercept from hole CDH006, the first hole from a new step-out drill pad at the Cobrasco Project in Chocó, Colombia.
Following the high-grade Cu-Mo intersections reported in recent drillholes CDH003 to CDH005, drillhole CDH006 was collared on a step-out platform located approximately 400 metres northwest of the previous drill pads. The hole was designed to test the northwest extension of the mineralized system and is the first of several holes planned from this location.
Assay results from CDH006 are highly encouraging, with near-surface mineralization commencing at 38 metres within weathered saprolite and continuing through multiple anomalous intervals in rhyodacitic porphyries to a faulted contact at 808 metres. Two additional holes have since been completed from the same drill platform in rapid succession. Visible mineralization has been observed in both holes, and assay results are pending.
Highlights: CDH006 confirmed the continuity of the Cobrasco Central Cu-Mo mineralization system to the northwest: 486 metres at 0.42% Cu, 51ppm Mo, 1.20 g/t Ag, including 336 metres at 0.51% Cu, 53 ppm Mo, and 1.50 g/t Ag, including 232 metred at 0.68% Cu, 75 ppm Mo, 2.0 g/t Ag from 38 metres.
Additional step-out drillholes CDH007 and CDH008 have been completed from same drill platform testing extensions to mineralization in NE and N orientations (assays pending).
The ongoing program of drilling has added to the known mineralization footprint at Cobrasco Central, with ev ery drillhole completed to date returning significant porphyry Cu-Mo mineralization from surface or near-surface to depths of approximately 600 metres.
Systematic step-out drilling continues to expand the known mineralization footprint within the upper 600 metres, already covering a lateral extent of approximately 950 x 525m, which remains open in all directions.
Significant porphyry complex, comprising multiple intrusive phases, subvolcanic flow-domes and mineralization events demonstrated at Cobrasco Central. The mineralized system currently remains open in all directions and will continue to be targeted in Andina’s ongoing drill program.
Joseph van den Elsen, Andina Copper’s President and CEO, commented: “Every scout drillhole completed to-date has intersected significant intervals of Cu-Mo mineralization, further extending the mineralization footprint. This footprint now covers an area of at least 950 x 525m within the emerging Cobrasco Central mineralization.
“Broadly spaced, systematic ‘scout’ drilling will continue to define the limits of mineralization, which remains open in all directions, and to test newly developed targets. A new program of surface mapping and geochemical sampling is being prepared to run concurrently with this drilling and is intended to delineate multiple targets for follow-up sampling and drilling.
Preparations are also underway for the mobilization of a second drill rig, which will support both the definition of new mineralized targets and in-fill drilling across the widely spaced scout holes completed to date.”
Geology and Mineralization – Drillhole CDH006: Previous drillhole CDH005 was planned as a large step-out to the south, testing the extension of the Cobrasco Central mineralized footprint towards the southern limits of the concession boundary. This drillhole was notable for wide intervals of moderate-grade mineralization in a new intermediate porphyry unit of daci-andesitic composition. The discovery of large intercepts of Cu-Mo mineralization in this distinct magnetic host unit has opened broad areas for ongoing surface and down-hole exploration in the southern portions of the Cobrasco concession.
Drillhole CDH006 was collared approximately 400m NW of the previous drill pad #4 (CDH002 – CDH005) and approximately 300m SW of pad #1 (CDH001). This new location (pad #3) will be used to drill a fan of holes testing the overall NW-extension of the mineralization footprint.
Hole CDH006 (Az: 225o Dip: -60 o Depth: 898.90m), being the first hole from this drill pad was collared to test a SW section, parallel to holes CDH001 and CDH004, covering approximately 500m in the horizontal and 750m in the vertical planes. In broad terms, the lithologies intersected in CDH006 correspond to felsic porphyries of rhyodacite composition with mineralized intervals related to chalcopyrite sometimes replaced by bornite in intensely fractured rocks.
Hydrothermal alteration is strong argillic in the upper portions of the drillhole, progressing to phyllic and ubiquitous grey-green-sericite (GGS) which has been associated with the bulk of the mineralization defined thus far.
The importance of structural controls to the observed mineralization is more evident in drillhole CDH006 than in the previous holes. Here we can see a clear association between the structural preparation of the host units (shearing and brecciation – related permeability) and the resulting degrees of alteration and mineralization.
In general terms, the upper ~46 metres of the drill core are strongly weathered and characterized by saprolites with strong oxidation and clay formation. A low-angle fault-structure (sub-parallel to drill axis) at this point marks the introduction of high copper and molybdenum grades (e.g. sample G517536: 46–48 metres at 4.6% Cu, 1,495 ppm Mo).
The rocks bounding this structure are friable, with strong argillic alteration, with mineralization being predominantly pyrite-chalcopyrite with traces of bornite. At greater depths, lithology is characterized by more competent units of rhyolite and rhyodacite with local occurrences of quartz-sulphide veining. Alteration is typically weak to moderate GGS increasing to phyllic alteration particularly over zones of brecciation.
A well-marked zone of magmatic brecciation in the felsic porphyry units extends to 270 metres, typically characterized by an increase in A-veins and high Cu-Mo grades. The interval 38-270 metres contains the stand-out mineralized intercept reported in this announcement (232m at 0.68% Cu, 75ppm Mo from 38m).
A faulted contact at 808 metres marks the end of the magmatic-hydrothermal brecciation in the drillhole and the start of a distinct polymictic intrusive breccia showing matrix-supported sub-angular to sub-rounded rhyolite to microdiorite fragments in a pyritic matrix. Mineralization decreases markedly although sporadic mineralized intervals continue to the end of hole (e.g. Sample G543022: 894 – 896m 0.48% Cu, 58ppm Mo).