Here you can see a relatively young lava flow made up of obsidian grading to rhyolite. This lava flow was mostly homogenous so the obsidian and rhyolite have a nearly identical mineral composition. Actualy, the only difference between these two rocks is that the cooling was so rapid closer to the surface that the minerals had no time to crystalize and the end result is obsidian. Deeper within the flow the lava cooled much slower allowing time for crystylization which created the rhyolite.
Here you see the lava flow, the obsidian is the black and the grey is mostly pummice.
In this shot you can see the black obsidian layered with grey pummice.
This is the trail that winds across the lava flow with Paulina Lake in the background.
Here Kriss kneels next to a wall of obsidian along the trail.
It's amazing where life can sometimes crop up. This tree is growing out of about an inch of soil.
After leaving Newberry Caldera ,where it is illegal to pick up rock much less take it home, we dicided to go to Glass Buttes. This is probably the most aptly named mountain I have ever seen since it is actualy two buttes about two thousand feet tall, and made entirely of obsidian. There are two things that set it apart from Newberry, first there are many different types of obsidian, not just black. Secondly, it is perfectly legal to collect. Unfortunately I was so busy collecting obsidian that I didn't take time to shoot many shots.
A scree field of Mahogany obsidian.
