The modern, classy look of American Fire Glass Lava Stones adds a warm rustic elegance to any fire feature. These stones are naturally formed & then put through a smoothing process giving them their uniform shape. Because they are volcanic, they can withstand the most extreme temperatures without sustaining any damage or crumbling, making them a cost-effective, long-lasting & beautiful addition to your fire pit, fire bowl & indoor or outdoor fireplace. Lava stones offer durability and provide a low maintenance unique natural element that looks great as part of your indoor or outdoor decor. Design & Construction Features: American Fire Glass Extra Large Gray Lava Stones are made from natural occurring volcanic rock allowing them to withstand extreme temperatures without any loss of color or change in shape. Lava stones feature a smooth porous profile which provides improved air circulation resulting in a bigger brighter flame presentation. The beautiful color of the stones ranges from dark grey to black creating a dramatic, natural affect that will add a warm rustic elegance to your fire feature.