Lava Fyre Granuals - 10 lbs. are small pieces of lava rock (about 1/4" to 1/2") that are used to spread around the floor of the fireplace to fill in the empty space in front of and around the glowing embers and burner. This gives the gas log installation a more refined and finished look.
A 10 lbs. bag is typically enough for an average fireplace. For larger fireplaces, use two 10 lbs. bags.