Drunk on Petrology - Obsidian Stout

The next up on the Drunk on Geology series is the Obsidian Stout from Deschutes Brewery out of Bend, OR.

Obsidian is a shiny, very smooth, and (often) black igneous rock. It forms from the extremely quick cooling of lava, where no crystals have time to grow. This creates a glassy structure, where edges are able to sharpened to be sharper than a razor blade. 

Obsidian is found in areas of former or active volcanism, much like along the Northwestern US with the active Cascade Range volcanoes (where Bend, OR is located) or Hawaii. Obsidian generally consists of silica, a form of quartz (SiO2), that didn't have time to form larger crystals due to the quick cooling time. Surrounding Bend, there is also the Lava Lands Visitor Center and the Newberry National Volcanic Monument. 

A sample of obsidian

Obsidian Stout

"Deep, robust and richly rewarding, roasted malt and black barley give way to notes of chocolate and espresso. Smooth and black as the glassy volcanic rock fields it's names for."

 "Give in to the deep, dark spell as the layers unfold."

Some lovely obsidian layers courtesy of  Lockwood (Outside the Interzone)

Glamour shot