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

hydrothermal and autopneumatolitic origin also appeared in amygdaloids at the famous locality of Mulató Hill near Erdöbénye where more than 25 different minerals, many wellcrystalline, were found in fist-size or even head-size cavities (Fig. 13). Unfortunately, the Hubertus quarry, opened in the 1920's, was closed in 1983. On Kopasz Hill near Tállya, however, a similarly diverse association of minerals to that found near Erdöbénye occurs in andésite cavities (Fig. 14). The andésite is still quarried today for road and railway building, indeed the Kopasz Hill quarry is the largest in these mountains. Different kinds of hydrothermal mineral assemblages fill fractures in andésite and dacite. Those filled with zeolites (mordenite, heulandite, chabazite, stellerite, dachiardite) are well known (Fig. 16), but other more extensive assemblages, characterised by varieties of quartz and opal, are more widespread, which occur in veins, and lenses. These, so called, hydroqucirtzite veins are usually a few centimeter thick but some fissures may be several decimeters even a meter thick. Due to the presence of some colouring minerals (goethite, hematite, celadonite, nontronite, and Mnoxides), many colourful varieties of quartz and opal are encountered. Gems and ornamental stones are made from these colourful specimens at several places, and in particular, in the vicinity of Erdőhorváti, Tolcsva, and Komlóska. It may well be that this silicification occurred on a regional scale: geyserites are found here together with hydroquartzite, occasionally in massive zones a hundred meters wide (as at Sárospatak, Bot-kő Hill, and Király Hill). The appearance of cinnabar as well as barite is typical of these assemblages. Hydroquartzites may also carry some iron ore (Mád, Regéc). Another type of late stage volcanic activity is associated with limnoquartzites which as, their name already suggests, were formed in a limnical (freshwater, often marshy) environment. Their mineral assemblages are very different from those found in other hydroquartzites. One of their characteristics is the appearance of the arsenic- and antimony-bearing minerals stibnite and realgar and their oxidised products, stibiconite and scorodite. Occasionally, where