Small Lava Rock Small lava rock may be the perfect size material for your gas fire pit. These half and quarter-inch-sized pieces provide great coverage as a base material in addition to your fire pit products, such as 1/2-inch fire glass or even fire beads. A ten-pound bag of lava rock will fill as much area as twenty pounds of fire glass. You will discover that lava rock is an economical, efficient, and inexpensive fill material for your fire pit. Material: Lava rock Size: ¼” to ½” in diameter Color: Brown to black Available in 10 lb. and 20 lb. bags Your best choice to camouflage gas piping and tubes! If ceramic logs are your style choice of gas fireplace accessory, consider adding some of the lava rock around the area to create a very rustic and outdoorsy feel. Because it is a natural material, please remember your lava rock will differ in shades of brown to black. Of course, lava rock is a beautiful and unique natural mineral and will stand alone with any home or outdoor decor.