Obsidian is the result of volcanic lava coming in contact with water. Iron and magnesium give the obsidian a dark green to black color. Obsidian has been used by ancient people as a cutting tool, for weapons, and for ceremonial purposes. Beadaholique.com offers not only black Obsidian, but also mottled Snowflake Obsidian and Mahogany Obsidian in shapes such as stars, cubes, and more.