American Fireglass LAVAST-M-10 Gray Black Lava Stone - Medium 10 lbs These Tumbled Lava Stones are formed when volcanic lava encounters cool water from the ocean and hardens as a result. The naturally occurring lava stones are gathered up and then go through a 'tumbling' process which removes any sharp edges and gives them their uniform shape. Because they are volcanic, they can withstand extreme temperatures without crumbling or exploding. Tumbled Lava Stones give a truly unique and stylish look to any gas fireplace which is a refreshing change from the usual fire wood. They may be used exclusively, or as a base for other fireplace ornaments, such as fire glass or Light stones. The best part is they require no maintenance at all. Features Natural lava stone with a rolled appearance Smooth tumbled finish with round appearance Natural gray and Black in color Specifications Color: Gray Black Size: Medium Weight: 11 lbs