COPPERSTONE RESOURCES AB: DRILLHOLE COS18359 RETURNS 62m WITH 0.47% COPPER MINERALISATION AT APPROXIMATELY 500m DEPTH BELOW GRANLIDEN HILL
Published 13 June 2018
Copperstone Resources AB (“Copperstone” or “the Company”) is pleased to announce significant copper assay results from drillhole COS18359 in the Granliden Hill area. Details of the drillhole location, azimuth, angle and length are provided in the Technical Report – Update on 2018 Drilling Campaign published on the 17th May 2018.
62m of continuous chalcopyrite mineralisation intercept from 744-806m returning 0.47% Cu and 3.3g/t Ag, and containing a 10m zone from 752-762m returning 1.28% Cu and 9.2g/t Ag.
Drill hole COS18359
COS18359 was collared east of Granliden Hill and was drilled due west at -55 degrees dip to a length of 878m. From approximately 50m to the base of the drillhole fine- to mediumgrained altered quartz porphyry was intercepted with intercalated zones of pre-mineral micro-diorite, hydrothermal breccia and younger post-mineral intermediate dykes. Mineralisation consists exclusively of chalcopyrite with subordinate pyrrhotite, pyrite and arsenopyrite. Mineralisation styles are either stockwork-like veining over continuous zones, or discreet narrow veins. In some places veins are associated with micro-brecciation textures, associated with quartz and in general with little to no visual wall-rock alteration effect.
Note that all lengths quoted below are drilled intercept lengths and the true width of mineralisation is not known. In total three (3) zones of mineralisation were sampled in COS18359 as described below:
Zone 1 from 65m-109m (44m) contains a number of low grade chalcopyrite zones and three discreet chalcopyrite veins:
65-109m (44m): 0.17% Cu, 2.1g/t Ag
Containing 65-67m (2.0m): 1.04% Cu, 7.5g/t Ag
And 83-85m (2.0m): 0.90% Cu, 8.6g/t Ag and 0.1g/t Au
And 107-109m (2.0m): 0.88% Cu, 14.9g/t Ag
Zone 2 from 559m-592.5m (33.5m) contains a number of low grade chalcopyrite veins and a single higher grade vein:
559-592.5m (33.5m): 0.14% Cu, 0.9g/t Ag
Containing 571-573m (2.0m): 0.86% Cu, 6.4g/t Ag and 0.24g/t Au
Zone 3 from 744m-828m (84m) contains a continuous zone of chalcopyrite stockwork veining:
744-828m (84m): 0.37% Cu, 2.6g/t Ag
Containing 744-806m (62m): 0.47% Cu, 3.3g/t Ag
Containing 752-762m (10m): 1.28% Cu, 9.5g/t Ag
Chalcopyrite mineralisation found in COS18359 is similar in style to that found in historic drill holes from the Granliden Hill area. It is believed that the deeper intercept in COS18359 indicates that the extent of the system is significant in the vertical dimension, approximately 450-500m further below the known shallow intercepts (on average 150m vertical depth). At this stage there is no knowledge of the true width of the deeper mineralisation intercept. Chalcopyrite veining is hosted mainly in hydrothermally-altered quartz porphyry and also in micro-diorite (field description only).
Chalcopyrite mineralisation is apparently younger as it cross-cuts the host geology. The source of mineralisation is thus unknown but is tentatively suggested to have emanated from the east to south east, although these ideas need to be explored by further drilling. In relation to COS18358 drilled from the south it can be seen that individual veins of mineralisation are probably discontinuous so the bias of individual intercepts and widths of composited grade are largely dependent on the drillhole azimuth and dip relative to the overall trend of the mineralised zone.
Further exploration drilling is continuing to the east of the Granliden Hill area to find the possible causative source of the mineralising fluids and vapours. Given the extensive magmatic-hydrothermal nature of this system, it is believed that a discreet felsic stock(s) or dyke-like body might be in the vicinity of the Granliden Hill area emplaced along or close to the margin of the larger quartz porphyry body. This margin has been located with the NSAMT geophysical survey.
On a more general level the quartz porphyry body is extensive over the Copperstone property and is thought to represent a possible resurgent dome complex within a much broader caldera system. The quartz porphyry body does not appear to be typical of rhyolite flow dome complexes found in the Skellefte-field to the south of the property. Host rock geology to the east of the quartz porphyry complex consists of layered andesitic lava and subordinate arenite (pre-caldera) with an overlying sequence of siltstone, black shale and felsic pyroclastic strata (intra-caldera). Geology is also broken by a number of faults of unknown age and displacement.
Overall the geological architecture for this project is still evolving and through deep drill testing combined with careful application and interpretation of geophysical, geochemical, optical and mineralogical examinations Copperstone is rapidly unlocking the geological history and mineral potential of this property.
Core Assays and Quality Assurance / Quality Control
All drill core boxes were delivered by the Drill Contractor to the secure Copperstone Site Office 1km from the drill site. Before transport to Malå, preliminary inspection and logging is carried out by Copperstone personnel. Core is then logged in detail at the Copperstone Facility in Malå before zones for sampling are selected. Once sample zones are identified and ticketed core boxes are then collected for laboratory analysis.
Sample preparation including half-core sawing, crushing, splitting and pulverizing has been carried out at ALS Minerals Laboratories, an accredited laboratory based in Malå. Prepared 50g aliquot pulps are then couriered to their Analytical Laboratory in Ireland. Sample analysis is then 4-acid digestion followed by ICP finish (ME-MS61) for 49 elements, including Ag, Cu and Zn. All samples with greater than 10,000ppm (1%) Cu and / or Zn are re-run with 4-acid digestion and then ICP-AES finish (Cu-OG62 and Zn-OG62) with results reported in percentage. Gold values are determined with a 30g fire assay fusion with AAS finish (Au-AA23).
In total 156 samples each with a drill length of 2.0m were submitted as two separate batches for assay from COS18359.This represents approximately 38% of the NQ core in this drillhole. The certificated copper-gold standard reference samples used are OREAS 501C and OREAS 502C, as well as blanks and duplicate samples inserted at regular intervals in the sampling sequence in order to maintain Quality Control (accuracy and precision).A total of 21 qaqc samples (7 blanks, 7 standards and 7 duplicates) were submitted at a 1:20 frequency. All qaqc results reported by ALS are within acceptable limits for the two batches submitted for COS18359.
“This by far is the most significant drill intercept we have found from the 2017-2018 drill campaigns. This is a tremendous result in pursuit of the porphyry-style system we believe exists here. It is very encouraging that the mineralisation under and around Granliden Hill is extensive. A near continuous 62m of chalcopyrite containing 0.47% Cu and 3.3g/t Ag from 744-806m shows us that the deep system is there, as we expected. This copper mineralisation must be coming from an intrusive somewhere nearby to this drill hole and we are drilling now to try and find that source. Each new deep drill hole is generating brand new geological information on this exciting discovery quest. Our targeting is building steadily, our knowledge of the big geology picture is building steadily, and we hope in this summer to finally strike that causative source. ” comments Chris McKnight CEO of Copperstone.
For further information, please contact Chris McKnight (CEO) at +46(0)580-88890, or firstname.lastname@example.org or refer to Copperstone webpage: www.copperstone.se.
This press release contains insider information which Copperstone Resources AB (publ) is obliged to publish according to the EU market abuse regulation (MAR). The information was delivered by the above mentioned contact for publishing 13th June 2018 at 0800 CET.