Szakáll Sándor - Jánosi Melinda: Minerals of Hungary (Topographia Mineralogica Hungariae 4. Miskolc, 1996)

tite, and glauberite are relatively rare components of the assemblage here. Cavities in dolomite rock are filled with dolomite, magnesite, pyrite, millerite, and beautifully clear crystals of gypsum. In the clay cover of this evaporite deposit, crystal groups of secondary gypsum are to be found. Septarian marl concretions and nodules are also quite common. Cracks in these are filled with a varied mineral assemblage including: calcite, marcasite, pyrite, and aragonite. The Mesozoic sedimentary rocks of the Aggtelek-Rudabánya mountains have a mineral assemblage dominated by calcite and dolomite. Splendid crystal groups of calcite are known from Tornaszentandrás on Esztramos Hill (Fig. 25). Calcite pisolites, dripstones (stalactites and stalagmites) and milky crystals (mountain milk) occur in the many caves which are so characteristic of this region. In the deposits of bat guano in the caves, several earthy phosphate minerals (taranakite, carbonate-hydroxylapatite, brushite, and monetite) have been identified. Whilst, in the smaller depressions and hollows in Esztramos Hill, carbonate-hydroxylapatite occurs as thin crusts which may have formed from some tiny bones found there. The once industrially important hydrothermal-metasomatic iron ore deposits (at Tornaszentandrás, Martonyi, and Rudabánya) are hosted by Triassic dolomites (Fig. 26). One of the characteristic features of these iron ore deposits, particularly those at Rudabánya, is that they are associated with a very large and varied sulfide mineral assemblage of copper, lead and zinc and to a smaller extent of antimony, silver, arsenic, and mercury. Rudabánya is the biggest and most important of these mines. It was here, on Ruda Hill, that surface exposures of native copper were first probably exploited by copper-age Man, and where, in Medieval times, silver mining flourished - the silver coming from galena-bearing ore. At this time Rudabánya became a Royal Free City. Limonite, or iron ochre, was mined too at several locations in the region but on a much smaller scale. It was smelted in small furnaces, the remains of which are still extant. Later on during the 18th century even more emphasis was put on iron ore production. It was from here that the first larger foundries in the Bükk mountains obtained their supply of raw materials. Finally, towards the end of the