Black Obsidian is traditionally used for gazing, and insight into the future because it is a natural glass from the "Mother".
The intrinsic properties of the numerous forms of Obsidian produces a very stark and blunt vision of things as they are and things as they could be.
"Black obsidian is used in Shamanic ceremonies to aid the removal of disorder from the body...surrounding and transmuting it into white light." *
*"Love is in the Earth" by Melody