Gritstone is made up of the cemented deposits of rounded grains. These are the size of coarse sand to gravel. In some gritstones the grains can be easily rubbed out, while inothers a strong cement makes the rock suitable for use as agrinding stone, such as Millstone Grit. Quartz is always thegreatest component, but it often contains iron oxides giving it a yellow, brown, or red colour.


  • GRAIN SIZE: 1–4mm. 
  • ESSENTIAL COMPONENTS: Quartz , feldspar
  • ADDITIONAL COMPONENTS: Mica and many heavy and resistant minerals, such as garnet , rutile , and titanite
  • ORIGIN: Detrital, from grit. 
  • SIMILAR ROCKS: Sandstone is finer;feldspathic gritstone contains more feldspar.