OBSC-G-01 Origin: Mexico Grade: AA Dimensions: Approximately 40mm to 60mm Weight: Between 40-60g Origin: Mexico Quality: AA+ = Excellent Beautiful celestial eye obsidian pebble measuring 40mm to 60mm. The dimensions, colors, and patterns may vary from one stone to another. The pebbles were photographed using a camera with a flash to best highlight the reflections of the obsidians. Obsidian is a volcanic rock rich in silica. Different types of obsidians exist. They differ due to the chemical composition of the rock. Obsidian is actually a natural glass. It forms during a silica-rich lava eruption with less than 3% water.