clastic sedimentary

• Breccia is a course grained clastic rock. They are not generally transported long distances so have angular clasts. The coarse grains are often mixed with finer grains and set in a matrix, so they are poorly sorted. Breccias can form scree, alluvial fans and wadi deposits. 
• Conglomerate is a coarse grained clastic rock. They are often transported long distances so are rounded. The large clasts can also be surrounded by fine grained matrix and are poorly sorted. Some conglomerates are held in place by a mineral cement. They can be found on beaches and where river channels deposit sediment.
• Sandstones are 0.06-2mm in grain size and are used in building stone. They can be very porous which means they are poorly cemented or they can have a low porosity which means they are well cemented. Their main mineral is quartz but contain mica and k feldspar. 
• Orthoquartzite is a sandstone made of 90% quartz with grains held together by a quartz cement. The grains are well sorted and rounded, this means it has undergone extensive weathering so is often found at beaches and shallow marine deposits. 
• Desert sandstone is coated in iron oxide so is red in colour. It is course grained and very well sorted and rounded so the grains have a high sphericity. The clasts are cemented together by silica or iron minerals and is often found in arid environments
• Arkose is a medium grained sandstone that is made from mostly quartz and 25% feldspar. It is moderately sorted with grains that are sub-rounded to sub-angular so the sediment has not been transported for very long. Formed in alluvial fan environments in arid areas. 
• Greywacke sandstone contains fine to coarse grains. They are poorly sorted with angular to sub-angular grains. More than 15% of the rock is clay matrix. They often form in deep water environments. 
• Clay grains are very small and can come in a variety of colours. It can be moulded, and forms layers. 
• Mudstones are very fine grained and contain quartz and mica. They are not plastic and do not layer. 
• Shale contains very fine grains that makes distinctive layers. The rocky splits easily and is described as fissile. Shale is hard and brittle.