Obsidian, volcanic glass. Oregon.April 30, 2017/in /by Marli Miller primary foliation, banded https://geologypics.com/wp-content/uploads/2017/04/geologic-time-pics-logo-300x115.png 0 0 Marli Miller https://geologypics.com/wp-content/uploads/2017/04/geologic-time-pics-logo-300x115.png Marli Miller2017-04-30 19:43:302017-09-06 21:38:07Obsidian, volcanic glass. Oregon.