American Fyre Designs Lava Rocks are used as the base for other optional decorative media. Most fire pits require either lava rocks or fire glass to serve as the base for additional secondary media. Available in three styles - volcanic stones, lava fyre coals, and lava fyre granules. Lava fyre granules and coals are the perfect media base for those who want their fire feature to have a more traditional look. After adding lava rocks, you can add volcanicstonesor alog setto complete the look of your fireplace. Check your fire pit manual to get the right amount of lava media for your fire pit.