... filter material, points (natural) pebbles and (machining) quartz quality.the two kinds. Natural cobble is through natural ... 0.2%Bulk density1.85g/cm3 For paving stone:1Typecobble & pebble (river stone)2Material100% natural stone3Usagelandscaping, paving, building, ... Range1~3cm, 3~5cm, 5~8cm, 8~12cm6Color Availableblack, yellow, red, green, gray, white, mixed7Processwash, wax8Featuregood quality, low ...