The Copperstone exploration area in Northern Sweden has been the subject of several previous exploration programmes over approximately a 50 year period. Drilling has intersected a significant number of high grade sulphide mineralised zones, spread out over a 3x1 km area, bearing high grade copper-zinc-silver-gold mineralisation. Despite these significant drilled intersections, with excellent metal grades, there is currently no drill indicated mineral reserve outlined to date. This is due to the lack of any cohesive, interpretive exploration model for the drilled mineralisation and no clear idea what might be the overall prospectivity and orebody potential of the property.
Drill hole data indicates that drilling programmes have been clustered around early, well mineralised, drilled intersections or spread out to test discrete geophysical anomalies. Mineralisation has been intersected immediately below the overburden at sub-crop and down 200m into the bedrock. It occurs within extensively altered mafic volcanic, volcaniclastic and volcanosedimentary rocks below a variably thick glacial overburden forming an undulating surface topography.
On a regional scale the mineralised andesitic volcanics and associated sedimentary rocks are preserved as remnant zones within and between very large granitic plutons that formed an integral part of the Proterozoic, ca. 1.8 billion year old volcano-plutonic arc now exposed in Northern Sweden. Despite the antiquity of the region, the rocks and their contained hydrothermal mineralisation, are very well preserved and indicate excellent prospectivity for economic mineral resources.
During 2015-2016 Copperstone has invested in new exploration drilling programmes to further investigate and interpret historic drilled intersections on the property. While drilling, down hole camera work and related analytical studies have been employed to validate the considerable historic databases, additional information has been gathered to formulate and test a new exploration model. Despite the extensive databases for the earlier shallow drilling programmes it is clear that the main prospectivity of the property, and the opportunity to discover world-class mineralisation, lies below in currently untested areas.
Based on a complete re-evaluation of all data, it is concluded that the property displays significant evidence of a porphyry-style copper-gold mineralisation. The near-term exploration objective is to test this interpretation to discovery, and while a positive outcome cannot be guaranteed the exploration can nonetheless be clearly focused to quickly test this objective.
World-wide exploration, discovery and exploitation of porphyry-style mineralised systems have enabled them to be well understood, and their characteristics well recognised. However despite being significantly large mineralised systems with characteristic ore- body features, they are still difficult to find as buried or blind orebodies. At Copperstone key features characteristic of such mineralised systems have become more evident during, and as a result of, the most recent exploration programmes. Based on this recognition there is now the need to focus on evaluating this exploration model to discovery.
Key indicators of blind ore body potential still lying at depth include characteristic geochemical alterations halos of good scale, related fertile veining and the presence of a phreatomagmatic breccia diatreme directly associated with metal sulphides. Breccia characteristics include milling of altered wall rock fragments, the presence of feldspar xenocrysts, extensive silicification and the abundance of high grade sulphide veining. In addition the model is supported by geophysical interpretations that suggest a deep seated magnetic root from the postulated stock. Overall the tectonic framework is in keeping with the potential for hosting porphyry-styled hydrothermal systems. Leading indicators to porphyry-style mineralization have been identified resulting in the design of a drill campaign to discover and evaluate this major opportunity for the Company.
“There is extensive copper-silver-gold mineralization found in a raft of historic boreholes drilled on the Copperstone project. High grade mineralization pockets may be linked to an unseen larger-scale igneous event. This is exciting and is by far the most attractive exploration target for Coppertone Resources to establish world-class precious and base metal resources in Sweden” adds the lead project geologist Chris McKnight in a comment.
”The potential we have been seeing for some time has now taken more substantial form and of late we have received indications secure enough for us to publish a well substantiated hypothesis worth validating and then verifying. We look forward to the upcoming development with great interest” says Per Storm in a comment.
For more information, please contact Per Storm, Copperstone Resources AB, 0705–94 90 24, e-mail: per.storm@copperstone.se.
Copperstone Resources AB (publ) is an exploration company focusing on the Copperstone project in the vicinity of the Skellefte field. This project has the potential to become one of the biggest base- and precious metal deposits in the Nordic Region.
Copperstone Resources has thirteen exploration tenements covering c:a 11 360 hectare and two mining concession and one applied concession covering a total of 82 hectare.
G&W Fondkommission is the Certified Adviser for Copperstone Resources AB.
This message has been approved by the Copperstone Resources qualified person of Thomas Lindholm MSc, GeoVista AB.
