Black Obsidian is a rock that forms from volcanic lava cooling quickly giving it a glass-like appearance. A historic warrior stone, used to make tools and as a powerful talisman. Black Obsidian is a stone that will assist you in staying grounded, assist unbalanced energy, stimulate your intuition, divination, and to keep your energy clean and protected. 2.60lb Black Obsidian Obelisk. 8 1/2″ tall with the widest part of the base being 2 1/2″. Sizes, colors, shapes, and inclusions will vary.