Black Obsidian Cobble - Spalled Face prospecting Mined from: Sao Fransisco River

Mined from: Sao Fransisco River

What makes this one stand out is the stout shape and the large uninterrupted top face

or butterscotch nephrite with one polished face

which also includes apophyllite

The chlorite-rich coating or inclusion effect gives the upper growth a dark charcoal to nearly black look

Black Obsidian Cobble - Spalled Face prospecting Mined from: Sao Fransisco RiverMined from: Burns, Lake County, Oregon, U. S. A. Description: Black obsidian from the Burns area of Oregon is a natural volcanic glass with a clean, dark body color and a bright vitreous luster. A spalled face shows the fresh interior where the stone has broken with the curved, shell like fracture obsidian is known for, giving it sharp edges and a raw, glassy surface. It has a stark, clean look that makes it popular for display, flintknapping, and