10mm gravel is usually a 5-10mm graded material. Our "local" material is flint based but it comes in many different colours. 10mm Gravel can be used for: drainage, pipe bedding, planters, grass alternative, driveways and footpaths. 10mm Gravel is a mixture of materials. This depends on whereabouts in the country you are working and it can be any of the following: Flint, Limestone, Granite, Basalt, Quartz or Oolitic Limestone. It can also be a recycled product from reclaimed brick and concrete. Location affects the colour and type of material which is "local" to you and why there is such a large difference in coloured materials through the UK.