Obsidian is a glass like, black volcanic stone that was sort after in ancient days as it could be sharpened and used for cutting. Lipari was a major source of obsidian in ancient times, though it is found in other volcanic regions of the world.
The edge can be sharpened to molecular levels and is even used in modern times for cutting edges.
Obsidian is formed when a certain type of lava cools rapidly and freezes without sufficient time for crystal growth.
It is also very decorative and shiny like black glass.
Our guide wandered a few meters off the road and came back with some small pieces of obsidian.
Pumice is a white porous volcanic rock that is very light and actually floats. It is used as an abrasive exfoliant in beauty treatments to remove excess skin.
Pumice is still mined here today.
Howard [ Just Imagine ] 23-Feb-2008