Description of the fossil manganese nodules found in the Oligocene clay deposits of Moravia, Brno area, Czech Republic

In the green Oligocene clay of Krizanovice (former Krzyzanowicz) the author found numerous black nodules. In the 3-4 centimeter thick black crust of a particular specimen the concentration in MnO2 is evaluated at 46.6% MnO2. The determination was done using the Volhard's method (precipitation of Fe by ZnO and titration with KMnO4). Only the dissoleved part in HCL was analysed. The non soluble residue was essentially a silica precipitate in the form of many gray flakes. The specific gravity of the crust was evaluated at 3.8. In the internal yellow core the amount of manganese is about 2.39% MnO2. Due to the light color it is judged to probably be in the form of Mn2O3.

Behavior of trace elements in quartz from plutons of different geochemical signature: a case study from the Bohemian Massif, Czech Republic

Trace-element content in igneous quartz from granitoids of different geochemical types from Bohemian Massif (Central Evrope) was investigated using the laser ablation ICP-MS technique. Two laboratories (Geological Survey of Norway, Trondheim, and Institute of Geology of the Academy of Science of Czech Republic, Praha) were involved in the trace-element (Li, Be, B, Mn, Ge, Rb, Ba, Pb, Mg, Al, P, Ca, Ti, Fe, and Sn) analyses of quartz (altogether, ~300 analyses of 17 rock samples). About 200 representative analyses of quartz are given in Tables 1 and 2.