Tumbled Basalt Rocks (20-40mm)Our Tumbled Basalt 20 40mm pebbles are a bold, natural stone with a deep charcoal grey tone and a smooth, semi rounded finish. Sourced locally and tumbled for comfort underfoot, this larger format basalt is ideal for feature garden beds, pathways, pots and areas where you want contrast against lighter landscaping materials. Often chosen by customers searching for black rocks or black pebbles, tumbled basalt delivers a strong, dark aesthetic while