Gritstone or grit is a hard, coarse-grained, siliceous

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicat ...

. This term is especially applied to such sandstones that are

quarried A quarry is a type of open-pit mine in which dimension stone, rock, construction aggregate, riprap, sand, gravel, or slate is excavated from the ground. The operation of quarries is regulated in some jurisdictions to reduce their environ ...

for

building material Building material is material used for construction. Many naturally occurring substances, such as clay, rocks, sand, wood, and even twigs and leaves, have been used to construct buildings. Apart from naturally occurring materials, many man- ...

. British gritstone was used for millstones to mill flour, to grind wood into pulp for paper and for

grindstones A grindstone, also known as grinding stone, is a sharpening stone used for grinding or sharpening ferrous tools, used since ancient times. Tools are sharpened by the stone's abrasive qualities that remove material from the tool through friction ...

to sharpen blades. "Grit" is often applied to sandstones composed of angular

sand Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural class ...

grains. It may commonly contain small pebbles. " Millstone Grit" is an informal term for a succession of gritstones which are to be found in the Pennines (including the Peak District) of northern England. These sediments were laid down in the late (upper)

Paleozoic The Paleozoic (or Palaeozoic) Era is the earliest of three geologic eras of the Phanerozoic Eon. The name ''Paleozoic'' ( ;) was coined by the British geologist Adam Sedgwick in 1838 by combining the Greek words ''palaiós'' (, "old") and ...

era, in the

Carboniferous The Carboniferous ( ) is a geologic period and system of the Paleozoic that spans 60 million years from the end of the Devonian Period million years ago ( Mya), to the beginning of the Permian Period, million years ago. The name ''Carboniferou ...

period, in deltaic conditions. The Millstone Grit Group is a formal stratigraphic term for this sequence of rocks. The gritstone edges of the Peak District are an important climbing area and the rock is much relished by English climbers, among whom it has almost cult status and is often referred to as "God's own rock". The rough surface provides outstanding friction, enabling climbers to stand on or grip the subtlest of features in the rock. (See the main article on rock climbing in the Peak District.)

References

Sedimentary rocks Sandstone {{petrology-stub