Miscellaneous Obsidian Slabs
Obsidian is volcanic glass. It often has flow lines that create interesting
effects. Snowflake obsidian has a light snowflake pattern in a black
background. Gold and silver sheen obsidians display a flashy chatoyance
when polished. Rainbow obsidian displays a variety of reflecting colors
depending on the angle of light.
Obsidian has a reputation for being difficult to polish, usually
because too coarse a grit can create fairly deep fracture zones that
won't come out when the stone is cut at finer grits. Obsidian also
doesn't polish well if it gets too hot. So if you don't use super-coarse
grinding wheels and you keep your polishing wheel slow and wet, great
results will easily be obtained.
Example of the sheen effect when viewed at an angle.