Peace,
Black obsidian is a crystal created from the subconsciousness of planet ki, deep within volcanos then spit out and cooled into this beautiful stone. This makes a great tool for shadow work and releasing the information stored there so that you can reprogram your mind to your liking. Crystals are tools they will assist you as long as your follow through with the work.
We have a few pieces of black obsidian left here for $6.00 a piece