American Fire Glass LAVAST-XL-10 10 lbs. X-Large (4" - 6") Natural Gray Tumbled Lava Stones have a modern, classy look that 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 décor.