Foto: St. Jan Evangelista gallery
ano,
The gallery is carved in the phyllite of the Krkonose-Jizera Crystalline Complex, just near (north) of the Lusatian Fault. The opening part of the adit is reinforced with steel reinforcement, the adit is further on, except for fault zones and small excavations, without reinforcement and in places it follows the foliation in the phyllite. The veins are both steep and relatively flat and follow significant faults in at least two directions and have an irregular lenticular development, often without ore accompaniment. The vein consists of quartz (sometimes with a hint of star structures), abundant younger ankerite (weathering turns brown) and less common calcite. In a place called the Angel vein, there is pyrite or chalcopyrite and probably sphalerite interspersed in the quartz vein. Of the secondary, recently formed minerals, there are abundant rusty coatings of limonite, yellowish powdery probable jarosite, less frequent coatings of black manganese oxides, but very abundant is finely crystalline gypsum, forming glittering coatings on the walls. There is also a pink botryoidal erythrine in one, apparently formed from cobalt-enriched arsenopyrite. | Žáček, Vladimír | 2023