Informace o publikaci
Mica schists - principal raw materials for early medieval Slavic rotary querns in Moravia and Silesia (Czech Republic)
| Název česky | Svory - hlavní surovina na časně středověké slovanské žernovy na Moravě a ve Slezsku (Česká republika) |
|---|---|
| Autoři | |
| Rok publikování | 2018 |
| Druh | Konferenční abstrakty |
| Fakulta / Pracoviště MU | |
| Citace | |
| Popis | Raw materials for milling equipment have always been an object of the due attention in the past. Local rocks (especially granites, rhyolites, various clastic sediments) were used for crushers and saddle querns in the Neolithic to Hallstatt period. Rotary querns started to be widely used in the La Tene period and their appearance was accompanied by the origin of important production centres sometimes with large distribution areas. We know such workshops for Celtic rotary querns also in Bohemia, for example at the Kunětická hora Hill in eastern Bohemia (Tertiary tephritic phonolite), Žernoseky in northern Bohemia (Permian rhyolite ignimbrite) and around Přílepy in western Bohemia (Permian arcose). Lower Carboniferous greywackes of the Moravo-Silesian Paleozoic or sandstones from the Carpathian flysch belt were popular in Moravia. Occurrence of metamorphic rocks like gneiss or mica schist among raw materials for saddle querns or rotary querns is only exceptional. Similarly, especially various igneous (plutonic and volcanic) rocks were used in the following Roman and Migration periods. Surprisingly, the Slavic rotary querns from the Early Middle Ages in Moravia were made prevalently from totally different raw material – mica schist in spite of it the rock seems to be rather unsuitable for such purpose. At all important Slavic fortified settlements from the period of Great Moravian Empire, i.e., Mikulčice near Hodonín, Břeclav-Pohansko, Brno-Líšeň, Uherské Hradistě-Staré Město, mica schists form prevalent raw materials (roughly about 47% to 63%). They are followed by Slovakian rhyolites (up to 40%), gneisses (up to 20%), Carpathian flysch sandstones (up to 20 %), Miocene limestones, Permian arcoses, Culmian conglomerates. From archaeological literature it is evident that mica schist represents prevalent or substantially used raw material for Slavic rotary querns also in Lower Austria, Bohemia, Czech and Polish Silesia. Detailed petrographic studies revealed only a part of those raw materials can be classified as typical mica schist. Some of them correspond to macroscopically similar two-mica gneiss because of a higher content of feldspars. To distinguish individual mica schists from various natural resources it is necessary to determine composition of accessory minerals, which may be represented by garnet rich in aluminium (almandine), tourmaline, staurolite, and kyanite. Using microprobe the author with his students has investigated chemical composition of garnet and tourmaline of rotary querns from a few Slavic hillforts: Chotěbuz-Podobora near Český Těšín (Czech Silesia), Staré Zámky in Brno-Líšeň and Hradiště in Znojmo. The results were compared with composition of accessory minerals of mica schists or two-mica gneisses from already described early medieval workshops for rotary querns at Altenhof near Gars am Kamp (Lower Austria), Cucice near Oslavany (western Moravia), Kamieniec Ząbkowicki near Kłodsko (Polish Lower Silesia) and a potential source Švédské šance at Svojanov (western Moravia) to determine the provenance of Slavic rotary querns. |