Obsidian is a black, extrusive igneous rock that is often called volcanic glass due to its absent crystals and glassy appearance. Major minerals include feldspar, quartz, and mica. Obsidian cools so quickly outside of the volcano that individual crystals do not have time to grow.
An information card with details on the rock formation, mineral content, characteristics, and uses is included. Typical samples sizes are generally 1-2 inches in length or width but can vary based on availability and natural formation.
WARNING: CHOKING HAZARD-Small Parts. Not for children under 3 years.
May have sharp edges.