Board Thread:Off Topic/@comment-24993958-20151118083252/@comment-23702983-20151120045015

Obsidian is black. If the black is mixed with other colors it's because the obsidian merged with other minerals (not obsidian). It's composed of mostly silicon dioxide. If it isn't mostly black, it isn't true obsidian, it's a composite of other minerals with small amounts of obsidian mixed in.