25th March 2018:
Nowadays with increasing hunger for lithium, cobalt and other “modern” elements. Exploration for these resources is taking part also in Europe with the advantage of the Europe´s former active deposits having established infrastructure, stable political regime as well as relatively close processing plants and potential customers for buying the produce. Demand is mainly for electrical vehicle (EV) manufacturers, for example: Tesla, Jaguar, Ford, Land Rover or BMW. Several new projects are underway on the continent, and recently several new projects have launched, with Dobšiná being one of them.
The explosion of the exploration projects is tied to the unstable political situation in Democratic Republic of Congo, which is one the biggest producers of Co and Ni for European market. This, combined with an increasing price of Co on world market (around $80,000 USD/Metric Tonne), which is the highest price for almost a decade.
The hunger for Cobalt is still increasing, mainly due to EVs as well as the newest technology of rechargeable batteries, which may replace traditional Li-Lion ones in the future. Generally, usage of smaller amounts of Co are used in wide range of applications– from medicine through various industry alloys to catalyst for example for desulphurization reactions of natural gas and petroleum products.
Geologically, the ore veins of the Dobšiná are mostly hosted in gneiss – amphibolite metamorphic complex, which is located on the north on the town. Veins in this complex are mostly bounded to thrust planes as well as mylonitized faults. Grecula et al. (1995) divided mineralization in Dobšiná surrounding into 4 groups:
- Co – Ni mineralization hosted in Carboniferous Fe carbonates
Co – Ni mineralization creates irregular lentil shaped bodies in metasomatic ankerite siderite bodies. From the results of exploration from 1986 this mineralization contained:
Ni – 0,16 – 0,61 % in Dedičná adit up to 4,56 % Ni
Co – 0,07 – 0,36 % in Dedičná adit up to 3,62 % Co
Cu – 0,18 – 7,6%
- Co – Ni vein mineralization out of gneiss – amphibolite complex
This occurrence only has a small importance in Co mining. In the past these veins were mainly mined for silver.
- Co – Ni veins on the south border of gneiss – amphibolite complex (Martini type)
This type had quite big importance in historical mining. Generally, veins have direction W – E and steep slope, with inclination to South. Vein´s thickness is up to 50 cm, and mostly occur in stringers. According to exploration from 1962 veins contain:
Co – 0,02 – 0,5 % in Tešnárky stringer up to 3,2 % Co
Ni – 0,75 – 10 % in Tešnárky stringer up to 20,6 % Ni
- Co – Ni veins in the northern part of the gneiss – amphibolite complex
This occurrence of Co – Ni mineralization had the biggest importance in mining in Dobšiná. Occurrence can be divided into two systems Zemberg and Terézia, which are separated by N – S fault. Zemberg stringer consists of Južná, Hlavná and Severná vein. Severná vein is the only one exposed at surface. Hlavná and Južná ends in the overlaying Carboniferous limestones.
In general veins have direction SW – NE and slope of 40° – 70° with inclination to South. Terézia stringer consists of Terézia I and Terézia II veins. Both are almost identical with Južná and Hlavná veins. Vein filling in Zemberg – Terézia system is mostly represented by quartz, siderite – ankerite – calcite and ore minerals – arsenopyrite, pyrite, gersdorffite, tetrahedrite, more rarely chloantite, löllingite, Co – skutterudite, baryte and Cu minerals (typically chalcopyrite). Veins often mineralogicaly differs from each other and have vertical zonality. According to exploration in 1992 content of Co, Ni and Cu is:
Co – 0,1 – 0,3%
Ni – 0,1 – 1,6%
Cu – 1 – 7% (locally up to 11%)
Mining in the region has a lot tradition, not only in the Dobšiná, but across whole Slovak Ore Mountains. Begging of the mining in this area dates in to the age of Celts, who mined iron and gold. During middle ages mining of the copper, silver and mercury took place.
In 16th century production of iron began to decrease in Dobšiná, mainly due to exhaustion of the deposits, as well as unproductiveness of the siderite deposits. In 1780 Co – Ni ores were firstly explored, after that for almost 100 years Dobšiná become one of the biggest deposits of Co – Ni in the Europe.
Mining lasted here more or less till 1910. After WWII there were some small-scale explorations and reassessment of the resources carried, but with no positive result. In 2016 increasing price of the Co on global markets reopened question of the Dobšiná to be profitable deposit. Personally, I think it is possible, town has a good infrastructure, a lot of potential workers, with positive altitude to mining. Slovakia is country with stable political regime, so there is potential for Dobšiná into the future.
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Rozložník, O., Emmerich, H., Bachňák, M., Gašpar, J., Kilík, J., Magula, R., Mesarčík, I., Neubauer, M., Rozložník, M., Rozložník, O., Šmelková, E., Vozár, J. (2013): Banské mesto Dobšiná, vydanie druhé. – Banská Agentúra. Košice.
Lubomir Kyrc is an MSc Geology student at Masaryk Univerzity in Brno, Czech Republic researching mineralogy of ore minerals at Dobšiná.
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