Harrow and Hillingdon Geological Society

Previous Meetings

Mining and Pollution in Macedonia (Balkans)

Dr David Alderton
Royal Holloway College London

Macedonia is an area associated with Alexander the Great and fruit salad! Nowadays, only Turkey recognises the name Macedonia as to all other counties it has become FYROM or the former Yugoslavian region of Macedonia. The area is contained within the Alpine fold belt in Europe dating to the late Mesozoic period when the ocean of Tethis became closed as Africa moved northwards. The subsequent continental collision gave rise to sub-duction and mountain formation. This included four sets of mountains, Alps, Balkans, Carpathians and Dolomites (ABC & D).

Mines in Macedonia

Some are now disused but others are still being worked to produce: Pb, Zn, Cu, Ni, Sb and As. The capital of this region is Skopje famous for its earthquake. The Vardar zone yields ophilites, melanges, chromite etc. Pillow lavas are found locally and are remnants of the ancient ocean floor. Nickel laterite mining is also associated with this area. The lava flows and bedded tuffs were formed as the result of sub-duction and plate collision.

There are various styles of metal-ferrous mineralization yielding a variety of deposits.
1. Pb & Zn
2. Porphyry Cu
3. Epithermal Cu & Au
4. As & Sb
These are influenced environmentally, Pb Zn deposits as sphalerite, galena and pyrite and are obtained by lode cutting.

Sasa-Toranica, Pb and Zn mineralization is located in schists and marbles and there are massive replacements at the contact with an igneous rock called skarn. The metals are transported in acid fluids and then neutralised by alkalis. Limestone is a good host for mineralization.

Andesite is found in the Damjan region and Damjan skarn contains magnetites and the original limestone. There are several porphyry Cu deposits in Buchim and numerous small cross cutting veins in diorites. Buchim is worked as an open cast mine and the Cu is ≡ 0.5% and low grade. Epithermal Au and Cu have been altered by vulcanisation and are found in a caldera in Plavica. There are also silica caps on the hill tops which are worked for firebrick as it is pure quartz. Alshar Krstv Dol, Lojane are also areas of epithermal dissemination in altered volcanoes. These include Sb and As as sulphides and also thallium minerals. Strato-volcanoes, here different levels produce varying amounts of minerals by the mixing of magmatic and meteoric fluids. A modern analogue to this is the Yellowstone National Park thermal systems.

The Celts, Romans, Greeks and Turks all used metals from this region. They were worked mainly from river deposits but the Romans started actual mining for metals. Mining is still important today but is a declining part of the economy. The waste is dumped in dams and has given rise to massive contamination problems. Pyrite in the form of iron pyrites reacts with water to from sulphuric acid and iron oxide. The acid dissolves other minerals such as galena to form soluble lead sulphide and gives rise to high concentrations of lead in water. Oxidation of iron pyrites gives rise to iron oxide and there is no buffering against its effects by the host rocks. Some of the acid waters are neutralised by the calcium carbonate in the local limestone areas but as the water becomes alkaline the metals come out of solution. Around Skopje and Rosjanova antimony sulphide and arsenic oxide have been dumped leading to elevated levels of arsenic in the wells.

There are some advantages for mining in the area. There are lots of potential prospects and currently not much prospecting. The labour is cheap but there is a need for foreign revenue. However, there are also disadvantages. It is difficult to get licences because of fear of foreign exploitation and the environmental legacy.

	A picture of the surface outcrop of the lead-zinc orebody at the Zletovo mine. Because of weathering much of the mineralization has gone and is now made up of clay (white) and manganese oxides (black). The host rocks are altered volcanics (tuffs).
	A picture of a diamond drill core (cut in half) from an exploration borehole for copper and gold. Note the numerous small veins, some containing copper sulphides. A paragenesis can be developed as some of the veins clearly cross-cut others (and are themselves cut by other veins).
	Some of the students testing the water coming out of the Zletovo mine for pH (aciditiy). These waters are in fact quite acidic (pH of 3.5). Note the brown colour of the water due to suspended iron oxides. These are the products of weathering of pyrite in the mineral deposit.

Back to Top