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  • The Copperstone Project

Copperstone Resoures has, since 2013, evaluated the Copperstone project in the north of the Skellefte field in Arvidsjaurs commune. The area contains the mining concession of Svartliden K nr 1 and the applied mining concession of Eva as well as exploration permits in conjunction with these. In the evaluation, a method not earlier used in exploration in Sweden Optical Tele viewer which will be described below was used. The results of the interpretation have now been finalized and they indicate that the known mineralization’s are of the same type and origin and that area should be treated as one project. The potential in the area is presented as an “exploration target” according to the JORC standard1 and comprise 60 to 100 Mtonnes2 at 1 to 1,25 % copper equivalent (value metals re-calculated to copper using the following price assumptions: Au $1200/oz., Ag $20/oz., Cu $6500/tonne, Zn $2100/tonne, Pb $2100/tonne

Figure 1. Overview of the Skellefte field with active mines (blue dots), closed mines (blue triangles), processing plants (light blue rectangles) and the Norrliden Mining development projects (red stars). Light grey lines outline exploration permits by other companies. Purple areas outline active mining concessions.

What has been done is a summary and re-interpretation of more than 40 years of exploration history. Over the years, exploration work has been substantial but done in different periods. The work carried out during the last two years has been cohesive and systematic and new information through new methods have been added through the use of a new innovative method in exploration viz. the use of the Optical Tele viewer, (OPTV). This means that a TV-camera is lowered into an existing drill hole and filming 360° downhole and at the same time registers the direction and azimuth of the hole. With special software, the information is process and a correctly oriented 3-D presentation of the structures, rock types and boarders for different rock types is obtained.

The evaluation using the OPTV-measurements were combined with a re-logging of old drill core showing that, at depth, the geology in the in the southern part is the same as in other parts of the Copperstone project area and from this, the conclusion was drawn that Copperstone must be treated as a comprehensive project.

The evaluation was based on a thorough re-interpretation of the main part of the existing drill-core, field trips and both air-borne and ground geophysics. The interpretation included a compilation of all existing data and substantial re-analysis of the core composition which resulted in a new geological interpretation and 3D-modelling. An overview of the data situation is found in the box below.

Exploration information in the Copperstone-project

Earlier drilling campaigns:
1971-1978; 2004-2007
C:a 600 ha, average depth 120 m (33 – 445 m)

Data overview:
245 drill holes 33 610 m available drill core
3 188 samples comprising
4 436 m (average length 1,4 m)
747 re-analysed samples

As the final step, the different investigation areas were combined and using all available data, a coherent geological model was created. This indicates a large size mineralisation and through this, an Exploration Target comprising 60 to 100 Mtonne @ 1-1,2 % Cueq could be defined. The new geological interpretation also indicates that this is a new geological (sub)province. The Copperstone area is considered to be of another type of mineralisation than what is usually found in the Skellefte field. An aerial photo of the area is found in Figure 2 blow.

Figure 2. Aerial photo of the Copperstone project area with drill holes (yellow dots)

1 JORC is an Australian standard for mineral resource reporting
2 The Technical report for the Copperstone project was evaluated and approved by Thomas Lindholm, Geovista, QP according to JORC

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