In the Rodna Mountains, in metamorphic limestones, Upper Precambrian (over 540 million years old) stratiform (layered) lead and zinc mineralization occur, which are in some places crossed by Miocene (10-15 million years old) andesite, accompanied by hydrothermal mineralization. Here the main ore mineral of lead is galena (lead sulphide, PbS), while the main ore mineral of zinc is sphalerite (zinc sulphide, ZnS). They may be accompanied by large, golden-yellow pyrite crystals (iron sulphide, FeS2). In addition to them, other sulphides (e.g. boulangerite, bournonite) and various barren minerals (e.g. dolomite) can also be found at the site and can be seen in our exhibition.
In the picture: Sphalerite (black) and pyrite (golden yellow), Rodna (Romania). Image width: 10 cm. Photo by Géza Kulcsár.