... hard,mohs'8 3)Size:2-4,4-6,6-8,8-10,10-15cm Natural pebbles ... ball mill1.Product:Pebbles/Silica pebbles/Natural pebbles2.Size:2-4cm,4-6cm,6-8cm,8-10cm,10-12cm,12-15cm3 ... )COLOUR OF PRODUCT AFTER BURNINGGRAY AND WHITE7.Physical dataSpecific weight : 2,66Hardness(mohs): 8Porosity : 0,38 %Apparent density : 1,608 ... .to produce 1,000 kg of ceramic body,between 4 and 5 kg of pebbles will be necessary Dalian ...