Summary:
Copper mineralization in the Rudna concessions occurs over an area of 40.0 km2. The distribution of the various lithological types of ore is controlled by the relief of the top of the White Footwall Sandstone, principally by the disposition of elevations (hills) and flats (depressions or valleys). From south to north, the main elevations are:
- Southern Rudna Elevation on the 900 m level : isometric dome with a size of 1 km by 1 km in plan view.
- Central Rudna Elevation between the 950 m and 1,000 m levels : 300 m to 1,000 m wide ridge elongated west-northwest with flanks sloping 10 degrees southeast and northwest.
- Northern Rudna Elevation on the 1,050 m level : west-northwest elongated ridge with dimensions similar to the Central Rudna Elevation.
- Tarnówek Elevation on the 1,100 m level, with a width of about 800 m.
- Zelazny Most Elevation, interpreted from drill intersections in the northern margin of the Rudna mining area.
It appears that these elevations are simply ridges between broad and flat valleys of preZechstein origin. This hypothesis is supported by wedging out of the Cupriferous Shale over the elevations.
There are fundamental lithological differences between the elevations and the flats. A typical profile for the flats contains all lithological units, such as the White Footwall Sandstone, Boundary Dolomite, Cupriferous Shale and Basal Dolomite. Profiles through the elevations, on the other hand, begin with the White Footwall Sandstone which contains irregular patches of anhydrite cement and is overlain directly by the Basal Limestone unit, which begins with patches of algal dolomite and organogenic dolomite, locally covered by sandy dolomite. The higher units, beginning with streaky dolomite, are similar to those on the flats.
The monoclinal structure is complicated by two east-northeast-trending structures. The southwestern part of the mining area is cut by east-northeast-trending faults of the Biedrzychowa Fault system, extending from the Polkowice area. Throws are to the northwest and range from 40 m to 140 m. There are local elevations around shaft R-6 in the footwall block and, further north, the block is traversed by the west-northwest-striking Main Rudna Fault (200 m wide) with a throw up to 30 m to the north. This fault abuts the Biedrzychowa Fault. The second main structure, called Paulinowa, is situated to the west of the western shafts. The Paulinowa structure is a 20 m to 30 m deep syncline parallel to the Biedrzychowa Fault.
Characteristics and parameters of copper mineralization are controlled by lithological differences between the flats and elevations. The main zone in the south of the mining area follows a broad flat that extends into the Polkowice and Lubin areas. Mineralization extends from the top part of the White Footwall Sandstone (0.8 m to 4 m), through the Cupriferous Shale (0.4 m), clayey dolomite (0.1 m to 0.6 m) and streaky dolomite (1.2 m to 3 m), into the bottom part of the calcareous dolomite. The overall thickness of mineralization varies from 2 m to 6.5 m, the average being 4.5 m. Profiles through other flats are similar. The mineralized thickness in the flat between the Central Rudna Elevation and the Northern Rudna Elevation varies from 2 m to 7 m, but does not exceed 6 m in the flat between the Northern Rudna Elevation and the Tarnówek Elevation. In contrast, copper mineralization in elevated areas occurs in the White Footwall Sandstone and calcareous dolomite only. The mineralized thickness generally exceeds 7 m and locally exceeds 20 m. The extent of mineralization within the White Footwall Sandstone is controlled by the type of cement. Typically, the top parts of the elevations contain irregular patches of sandstone cemented by anhydrite or a mixture of anhydrite and clay cement and this type of sandstone is barren. When patches of anhydrite sandstone are thin, copper mineralization may continue uninterrupted beneath, but when anhydrite cement persists to greater depths, copper will not occur at all. On the whole, sandstone ore is more important and makes up a dominant proportion of the Balance Reserve at Rudna.