Obsidian

Obsidian is a beautiful natural stone formed by cooled volcanic lava. It's smooth and reflective and doesn't have a crystalline structure. Obsidian was so named from its resemblance to a stone found in Ethiopia by Obsius. It was used in antiquity for amulets and necklaces. From the paleolithic through historic times obsidian has been sought after and traded by native peoples. Obsidian is an excellent material for flint knapping (the process of making stone tools), it is smooth, hard, easily worked, predictable in its flaking characteristics, and produces a razor-sharp edge that can easily cut skin and flesh. Projectile points (arrow heads) and scrappers are the most common type of tool made from obsidian. Obsidian is a naturally occurring volcanic glass. It is usually an opaque black or grey but may be yellow, red, greenish brown. Obsidian may have an iridescent sheen caused by inclusions.