The "Steirische Erzberg" iron ore deposit is located 60 km NNW of the city of Graz in the province of Styria. Mining took place since Roman time. In the 16^th century underground mining started, which was closed down in 1986. Since the 18^th century open pit mining activities increased, which are still underway. Since the beginning of mining activity about 230 million t of iron ore have been mined at the Erzberg; 200 million t in this century. There are still 140 million t of recoverable and another 95 million t of geological reserves left.

Photo. 1

The Erzberg is the biggest iron ore open pit mine in central Europe (photo 1). Mining activities encompass the whole mountain, which rises about 700 m above the bottom of the valley up to 1400 m above sea level and covers an area of about 6,5 km². Mining is done in about 30 levels with an height of 24 m (photo. 2) . The annual production is approximately 3 million tons of iron ore with an iron content of 21%. Main ore minerals are siderite, ankerite and ferrous dolomite. Accessory minerals are pyrite, arsenopyrite, chalcopyrite, tetraedrite and cinnabar.

Photo 2

The open pit mine can be subdivided into different areas with regard to specific land use conditions:

Active mining areas exhibit fresh rock surfaces of different lithologies. Abandoned mining areas comprise weathered rocks of different types covered by vegetation of different intensity and condition. Dumps and heaps consist of material of different lithological mixtures, of different grain or block size, at different slope angle. Depending on their status of use heaps and dumps show no vegetation at all or are covered by different types and intensities of vegetation. In tailing ponds fine grained material is deposited.

Mining dumps comprise an area of about 3 km²; 0.6 km² is used as a test area for mining site landscaping and reforestation in an Alpine environment, and is covered by different types of vegetation. These activities are carried out by a consortium of university institutes and local consulting companies ("Development of standards for the renaturation and recultivation of mining sites and quarries", "Soil reconstruction over alpine mine tailings"). In the framework of these projects a lot of relevant parameters for the reforestation of mining areas in an alpine environment were acquired. (ground composition, grain/block size of material, vegetation type, vegetation stress, ...)

Landscape degradation

Alpine environment is extremely sensitive regarding the interference in the natural ecosystem. Open pits, mining dumps, and tailing dams are a severe degradation of the environment. Due to the specific climatic and topographic conditions in an Alpine environment nature's self-healing capabilities are considerably reduced. As in this area the economy relies on tourism to a considerable extent, human support is needed to minimise the negative effects of mining activities and to speed up the process of mining site re-naturation.

Landslides - dump slope stability

Not stabilised mining dumps are potential thread because of the possibility of dump slides, endangering people, infrastructure, and the environment. Dump stability depends on many factors, e.g. type of material, grain or block size, slope angle, thickness, water content, and type of cover (uncovered material, different types of vegetation). Mining dumps can be stabilised by means of landscaping and reforestation, thus regulating water balance within the tailings.

Contamination