Obsidian or volcanic glass from Mexico. Black and impure red obsidian is swirled togethed by nature to form the mahogany obsidian. Obsidian is an extrusive igneous (volcanic) rock formed during the fast solidification of lava with a certain composition.
You will receive 1 KG similar to the ones on the photo. On average between 20 and 25 pieces. Unsorted, mixed quality.