Fire Pit Essentials 10 lbs. Black Lava Rock 3/4 in. 01-0356 - The Home Depot

Natural volcanic lava rocks are excellent base layers and cost-effective fillers for gas fire pits and fireplaces. Fire glass, ceramic balls and other decorative fire pit products can be added on top of the fire rock for effect. If you like the look of these angular lava rocks alone, theyre an affordable way to fill a fireplace. Lava rock is available in two sizes and colors.