| Obsidian Slabs
Obsidian is volcanic glass. It often has flow lines that create interesting
effects. Flow Obsidian, also known as Midnight Lace, has striking translucent,
colorless flow lines against a black background. Snowflake obsidian
has a light snowflake pattern in a black background. Gold sheen and
silver sheen obsidians display gold and silver chatoyance when polished,
rainbow obsidian displays different colors, etc. Obsidian has a reputation
for being difficult to polish. Usually the reason for difficult polishing
is that coarse grits can create a fairly deep fracture zone that doesn't
come out when the stone is cut at finer grits. Another problem is obsidian
doesn't polish well if it gets too hot. So, if you don't use super coarse
grinding wheels and if you keep your polishing wheel slow and wet, good
results will easily be obtained.
Example of the sheen effect when viewed at an angle.