User blog comment:Stormjay Rider/The Volcanic and Obsidian worlds/@comment-4706022-20130829005832

Hm. If we were not to combine them, could there still be a big black volcano in the center of the Obsidian world? That would explain where the Obsidian comes from.

Also, for some contrast, I was thinking either the Obsidian or Volcano world of

having-get this-blue lava http://www.roflcat.com/images/cats/Deal_With_It.jpg