If you are looking for a classy alternative to traditional gas log sets, try Real Fyre River Rock Fyre Stones. With a superior quality of durable refractory ceramic, they are sure to get your guest's attention with their realistic and stylish look. Unlike natural river rocks, Real Fyre River Rocks will not crack or pop in your fireplace. These stones are designed to be placed on top of a bed of fire glass or lava stones for the best effect. Your set of river rocks come with ten pieces of varying sizes to provide a more realistic look to your hearth. Features Crafted from Refractory Ceramic with a Natural Look. Add a Touch of Nature to Your Gas Burner Setup. Set of 10. Specifications Material: Fiber-Reinforced Refractory Ceramic.