Volcanic scoriae

Volcanic scoria is a rock classified by its texture, rather than by its mineral composition. Volcanic scoria forms during an eruption, when gases escaping due to decompression turn lava into foam and rip it to pieces. Scoriae are usually loose and unconsolidated, but individual pieces may occasionally weld together and create larger blocks. Fresh scoria fragments are highly porous with sharp and irregular surface – due to a high volume of voids. According to its composition, scoria from Komorní hůrka Hill is petrologically classified as olivine-sodalite melilitite.

Komorní and Železná hůrka Hills in the Cheb region are among the youngest manifestations of volcanic activity in Bohemia. The age of both volcanoes, built predominantly by Strombolian style eruptions, is estimated to be less than 500,000 years.

Komorní hůrka Hill played a critical role in the development of Earth sciences. An experimental adit dug beneath Komorní hůrka Hill served as the final judgement place in a long-lasting controversy between Neptunists and Plutonists. According to Neptunists doctrine, all volcanoes result from underground burning of coal-seams. On the other hand, the Plutonists advocated an idea that volcanoes are products of outpouring molten rocks ascending from Earth’s interior.

Sample donated by Nature Conservation Agency of the Czech Republic, Protected Landscape Area Administration Slavkovský les.