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

real boom did not take place until the end of the 19th century when the iron foundry at Diósgyőr was opened. From then on these coal deposits played an important part in the development of the industrial region of Borsod county. A number of primary minerals occur on the typical and conspicuous spoil-heaps of these mines. Following the spontaneous ignition of these heaps, slow burning produced some interesting secondary mineral assemblages which, unfortunately, consisted of very soluble sulfates that were destroyed by erosion or washed away by rain. Today, minute crystals of sulfur, forming thin yellow crusts, and various sulfate minerals (mascagnite, alunogen, tamarugite, letovicite), appearing as thin white or yellowish brown coatings, or in clumps are the main minerals to be found (Fig. 23).