Siltstone
Sedimentary rock which has a grain size in the silt range / From Wikipedia, the free encyclopedia
Siltstone, also known as aleurolite,[1] is a clastic sedimentary rock that is composed mostly of silt. It is a form of mudrock with a low clay mineral content, which can be distinguished from shale by its lack of fissility.[2]
Although its permeability and porosity is relatively low, siltstone is sometimes a tight gas reservoir rock,[3][4] an unconventional reservoir for natural gas that requires hydraulic fracturing for economic gas production.[5]
Siltstone was prized in ancient Egypt for manufacturing statuary and cosmetic palettes. The siltstone quarried at Wadi Hammamat was a hard, fine-grained siltstone that resisted flaking and was almost ideal for such uses.[6]