SiO2>99.31%,low iron Hardness>8,more than French pebble Our own silica mine& ... ballsProperty: Round grayish silica stoneSize: 2-4cm, 4-6cm, 6-8cm, 8-10cm, 10-12cm, 12-15cmApplication: Silica pebbles can be used ... . We welcome any interested customer come to visit us.4. Our own logistics company will provide you a better ... silica man-made pebbles (round,1-2cm,2-4cm,4-6cm,6-8cm,8-10cm,10-12cm,12-15cm)