Obsidian is a naturally created glass. It is formed form volcanic lava which cooled too quickly for significant crystallization to occur. Snowflake Obsidian brings peace of mind and helps the stomach, sinuses, veins, bones and eyesight. Great for meditation, behavior problems, lonliness, blocks psychic attacks, and absorbs negative energy. Large pieces sold by approximate weight 1lb from China. Anywhere from 1" - 2"+ however a small piece may be mixed in.