Dragon Glass 1" Lava Pebble, 20 lb, Black Sourced from lava fields in Asia Pebble size 3/4" - 1 1/2" Tumbled to create a more uniform shape and unique look Rectangular fireplace/fire pit, (length x width x height) / 21 = pebbles (lbs.) Round fireplace/fire pit-(diameter x diameter x pebble height) / 26 = pebbles (lbs.)