name='limqareb' said:obsidian is a kind of glassy rock which is not black in that area but a greenish colour it depends on the area
surely obsidian is obsidian? and obsidian IS black
name='limqareb' said:listen the island of santorini is a big caldera that has collapsed thats why its kind of a circle the island formed , yes it was an active volcano long time ago , i have been to those islandsi know what im talking about ... i ll try to find somme piccars
That further supports the fact that it is volcanic rock, not ash.
Anyway this is a welcome back thread, not a geology lesson so back on topic.