The Chain of Volcanoes in Slovakia; The Slanske Hills: Geology Hub

[SwordfishMining]

The minerals & the conditions to form opals are volcanic in their origins. Sure they may settle out in an ocean environment also but silica comes from lava and the electricity is focused in few areas below water level or it is just opalite or agate if the water content is not right.

Approximately 10 million years ago, a large section of eastern Slovakia was the site of a chain of erupting volcanoes, several of which were erupting at the same time. Known as the Slanske Hills, these features are now all long extinct, but have left behind numerous mineralization such as precious opal, stibnite, lead ore, and zinc ores. This video discusses how this 55-kilometer-long chain of 13 ancient volcanoes came to be, and some fascinating remnants of their explosive history.