What is a sandstone in geology ?

Sandstone : definition

A sandstone is a detrital sedimentary rock composed of more than 85% of more or less rounded quartz grains, with a size between 62.5 µm and 2 mm. Sandstones are very common rocks in sedimentary series. They are subdivided into many varieties according to the grain, the nature of the elements and the cement (siliceous, limestone, clayey, ferruginous, etc...). Lithic sandstones with rock fragments are usually called grauwackes, those with detrital feldspars are known as arkose, those with detrital mica as psammite.