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Copperstone Resources Ab: Porphyry-Style Potassic Alteration Discovered at Granliden


Published 23 March 2018

Copperstone Resources AB (“Copperstone” or “the Company”) is pleased to announce results for drill holes COS18356 and COS18357 collared at Granliden. These are the first two drill holes of the 2018 drill campaign that is focused on exploration for a porphyry-style system to explain the existence of quartz veins containing chalcopyrite mineralisation in this area.

On the 12th December 2017 it was reported that geophysical mapping supports the hypothesis of a larger porphyry-style copper mineralisation system occurring across contiguous exploration properties held by the Company in Arvidsjaur Kommun, northern Sweden. The physical evidence for widespread hydrothermal activity to date has included characteristic alteration patterns (phyllic and propyllitic), the occurrence of hydrothermal breccia as well as the numerous copper-bearing sulphide veins identified in historic boreholes. To date none of these historic drillholes (263 collars, 38.7km drilling) have found the inner high temperature early part of the envisaged alteration system (potassic alteration), the causative intrusive, nor the predicted later mineralised stockwork zones that may exists on the boundary of the potassic-phyllic zone. As potassic alteration can be accompanied by secondary magnetite, the untested ovoid deeper magnetic target (Target A) was chosen as a start point to illuminate the alteration architecture and find proof-of-existence of a porphyry-style system.

Both 2018 drillholes were collared at the same position on Target A between Granliden South and Granliden Hill (exploration permits Sandberget 200 and 300 respectively). COS18356 was drilled due east on azimuth of 090 at an inclination of -65 degrees below horizontal. This drillhole encountered bedrock from 16.3m and was terminated at 638m in broken ground. COS18357 was then drilled vertically from the same collar position and encountered bedrock from 16.9m. This second drillhole was stopped at 711m. The following section describes what was logged in these two drillholes.


  • 16.3m – 110.7m: Strong phyllic alteration (quartz-pyrite-sericite) overprinting wall rock lava, pyroclastics and edge of lower granite.
  • 110.7m- 135.4m: Coarse-grained potassic altered granitic intrusive with a number of younger mafic intrusives (possible dykes).
  • 135.4m-361.4m: Pervasive potassic alteration (k-alteration) developed in coarse granite intrusive with remnants of feldspar porphyries and secondary magnetite, anhydrite (calcium sulphate), epidote and biotite. Strong pink colouration due to orthoclase feldspar. Incipient phyllic alteration as selvedges around fine quartz-biotite veinlets.
  • 361.4m-559.5m: Finely fragmental uniform mafic breccia/intrusive with occasional blocks of k-alt granite, narrow dykes. Younger and cross-cutting the overlying granite.
  • 559.5m-594.9m: Coarse-grained intermediate-mafic dyke with poorly formed porphyritic texture, no obvious k-alteration, faulted and brecciated in places. Younger than granite.
  • 594.9m-628.5m: Grey uniform diabase dyke with numerous quartz-calcite veins.
  • 628.5m-638m: Fault zone, silicified and brecciated rock, very broken ground.


  • 16.9m-155.8m: Phyllic alteration overprinting lava, pyroclastics and edge of granite intrusive.
  • 155.8m-618.9m: Very uniform pervasive potassic altered granite, with obvious incipient sericite selvedges to 338m, increasing magnetite and anhydrite with depth. Sub-horizontal quartz veinlets with no wall rock reaction from 560m depth.
  • 618.9m-711m: Dark greenish grey coarse to fine-grained intermediate-mafic intrusive with poorly formed porphyritic texture. Younger than granite and possibly sill-like.

Geochemical analysis of the granite found in both boreholes shows strong enrichment in both potassium and sodium. Although no whole-rock analysis has been carried out to date, trace and major element geochemistry based on ME-MS61 analysis techniques indicate a total alkali oxide content of 8-10% developed continuously over the body. Bulk silica content is likely to be greater than 70%, classifying the rock as high alkali granite at this stage. Other trace metal plots suggest this granite to be I-type, typical of porphyry style intrusives. However it should be noted that this rock has undergone extensive metasomatism with gross change in original bulk geochemistry. Further geochemical and mineralogical work is required to truly classify the type of felsic intrusive and alteration overprint. For simplification this rock is described as granite at this stage.

The granite also shows an increase in magnetite-anhydrite content with depth and is considered to be typical of early stage high temperature pervasive alteration associated with emplacement of porphyry stocks. Both drillholes have not found the edge of this body and it is highly likely that both are drilled within the classic central barren part of the intrusive porphyry stock. Numerous fine quartz and biotite veinlets are present, and many have sericite altered selvedges (margins) typical of B-C style veinlets found in porphyry systems. It is possible that the younger cross-cutting intrusives form post-mineralisation stocks, dykes and sills. There is also evidence of a major WNE-ESE trending structural zone associated with Target A.

This is the first time that potassic alteration / granite intrusives have ever been found on this property and that is extremely encouraging for the hypothesis of a porphyry-style copper genetic model. Interpretation of these drill results on the NSAMT sections suggests that a tall linear intrusive body trends NNW under Granliden Hill. Drilling is ongoing in this area to define the geology and alteration patterns, and to locate potential mineralisation zones within the developing porphyry-style model.

We are pleased to have located a key piece of the porphyry copper model in our very first attempt at Granliden. This is a hugely significant step in the right direction and I’m very encouraged that we are on the right path to discovery. There has always needed to be an explanation for the copper-rich veining in the local area, and this porphyry idea has always made the most sense to me. There is still however a lot of ingenious work required to follow out this k-altered granite, work out the alteration patterns and find the stockworks somewhere within that system around Granliden. Unlike shallow repetitive resource drilling, fundamental deep geological exploration drilling is rarely carried out these days, and it takes time to evaluate brand new geology like we have just uncovered. We have a unique opportunity to test our hypothesis, make discoveries here and show our courage to face this challenge” comments Chris McKnight CEO of Copperstone.

For further information, please contact Chris McKnight (CEO) at +46(0)580-88890, or or refer to Copperstone webpage:

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 23rd March 2018 at 0800 CET.


Copperstone Resources AB is a public company trading as COPP B on NASDAQ First North (Stockholm). The Certified Adviser is Augment Partners AB. The Company is focused on base and precious metal exploration in the vicinity of the internationally-recognized mining region of the Skellefte-field in northern Sweden.  The Copperstone project is situated on four contiguous exploration permits in Norrbotten County (Sandberget 100 (8074ha), Sandberget 200 (19ha), Sandberget 300 (19ha) and Svartliden 1001 (444ha). In addition the Company owns one exploitation concession within the same area, namely Svartliden K no. 1 (36ha) and an approved application for Eva k no. 1 (34ha) subject to an objection. The Company also owns the Tvistbogruvan K no. 1 (11ha) exploitation concession and the Såggården No.1 (199ha) exploration permit in the Bergslagen mining region of central Sweden.  Quoted surface areas are approximate to the nearest hectare. All exploration permits and exploitation concessions are 100% owned, either directly or through a subsidiary.

Qualified Person

All information in this press release has been reviewed and approved for publication by the appointed independent Qualified Person Mr Thomas Lindholm (M.Sc. Mining Engineering) of Geovista AB.  Mr Lindholm is a registered Member of the Fennoscandian Review Board and has in excess of 35 years' experience in mineral exploration in Sweden and abroad and is a Qualified Person under the Nasdaq First North Stockholm rules.  Mr Lindholm consents to the inclusion of the information in the form and context in which it appears.

Forward-looking Statement

News releases, presentations and public commentary made by the Company, and its Officers, may contain certain statements and expressions of belief, expectation or opinion which are forward-looking statements, and which relate, inter alia, to interpretations of exploration results to date and the Company's proposed strategy, plans and objectives or to the expectations or intentions of the Company's Directors. Such forward-looking and interpretative statements involve known and unknown risks, uncertainties and other important factors beyond the control of the Company that could cause the actual performance or achievements of the Company to be materially different from such interpretations and forward-looking statements. Accordingly, the reader should not rely on any interpretations or forward-looking statements; and save as required by the exchange rules of NASDAQ First North (Stockholm) for listed companies or by applicable laws, the Company does not accept any obligation to disseminate any updates or revisions to such interpretations or forward-looking statements. The Company may re-interpret results to date as the status of its assets and projects changes with time expenditure, metals prices and other affecting circumstances.