Molybdenum creates various genetic ores types which usually occur separately. Considering the economic value, the most important are molybdenum deposits of a porphyry type (Mo and Cu-Mo sub-type) with skarn, greisen, hydrothermal, vein, weathering and so-called “molybdenum sedimentary rocks” deposits of a much less importance.
Myszków deposit of molybdenum-tungsten ores with copper is situated at the north-eastern margin of the Upper Silesian Coal Basin (map), in the contact zone of the Małopolska Block and the Upper Silesian Block separated by the Hamburg-Cracow tectonic zone. The deposit is of the Mo-W-Cu porphyry type. Its ore mineralization is of the stockwork type, forming a system of quartz veins with ore minerals sulfide and oxide related to the Variscan sour igneous and dacitic (about 300±5 million years of age) activities. An intensive drilling program from the years 1975-1992 made possible the detailed exploration of Myszków deposit in the area of 0.5 km2 and down to the depth of 1,300 m. The exploration carried out in 1993 allowed to estimate inferred resources of the deposit in the Polish C2 resources category (the documentation prepared by Polish Geological Institute). Anticipated economic resources of ores occurring at the depth down to 1,000 m were estimated at about 380 million tonnes, with 0.23 million tonnes of Mo, 0.18 million tonnes of W and 0.55 million tonnes of Cu and a mean content of Mo and W equal 0.049% and 0.041%, respectively. As a result of the verification carried out in 2007 anticipated economic resources of Myszków deposit in C2 category are actually estimated at 551 million tonnes of molybdenum-tungsten ore with copper and anticipated sub-economic resources at 750 million tonnes. Anticipated economic resources of molybdenum are equal about 0.295 million tonnes, tungsten 0.238 million tonnes and copper 0.8 million tonnes and anticipated sub-economic resources are equal: 0.298 million tonnes of Mo, 0.212 million tonnes of W and 0.771 million tonnes of Cu (Table 1). Myszków ores have not been exploited so far. It should be added that according to the available data there are high chances for a discovery of other deposits of Mo-Cu porphyry ores with tungsten in the zone of the sour Variscan intrusions occurring along the tectonic Cracow-Lubliniec zone separating the Małopolska Block from the Upper Silesian Block.
Except of porphyry type ores, molybdenum occurs also in copper ores deposits located in the Fore-Sudetic Monocline and in hard coal deposits within the Upper Silesian Coal Basin area. Nevertheless, molybdenum is not being recovered during technological processes. Numerous occurrences of the Mo-W mineralization have been also found in zones of Late Carboniferous granitoid intrusions in the Sudety Mts, but no concentrations of an economic importance were found so far in this area.
Prepared by: Stanisław Z. Mikulski