Board Thread:Suggestions forum/@comment-27699761-20160131201549

Since Mordor was around a vulcano wich erupted many times it will be logical that on the surface of mordor you can find obsidian in chunks of like 10-35 and with the rarety of like 1%, in Far Harad Vulcano it should be 5% and the same amount and in Perthogowaith it will be 2% (you can somehow find Mordor bricks here also) this doesn't have a good pupose but it will be very realistic since obsidian is cooled-down lava  