Pyritic slates
Pyritic slates were used for production of "Czech" fuming sulhuric acid since 18th centrury when this branch of industry spreaded. This was quite remarkable at area close to Plzeň (Pilsen), Křivoklát ("Crooklog") and Rakovník ("Crayfishen"), where both small and large companies, mines and quarries were founded nearly by every outcrop of pyritic slates. In this region, many landmarks reminding the vitriolic industry may be found in woods and grown-over gorges of creeks flowing into Berounka river. Golden times of this industry have ended with arrival of 20th century, but it is still possible to identify ruins of oleum refineries, distinctive flat soak-dumps, retort shards looking almost like anthic amphorae and sometimes even dark entrances to adits among thorny bushes and nettles far from today's roads. The adits are often erratic, form larger chambers where it was required and sometimes meet other parts of systems on different height levels, so they may have almost cavelike appearance instead of human work. There is also plenty of colors, underground waters flowing over walls and footwall cover many parts of them by different sediments in red, orange, blue-greyish, white and yellow tones contrasting with emerging plates of black stone.