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Breccia is composed of coarse rock fragments held together by cement or a fine-grained matrix. [5] Like conglomerate, breccia contains at least 30 percent of gravel-sized particles (particles over 2mm in size), but it is distinguished from conglomerate because the rock fragments have sharp edges that have not been worn down. [6]
Breccia is typically silicified and consists of many smaller irregular rock fragments. Breccia pipe cutting Eday Sandstone, Ophir Bay, Orkney. A breccia pipe, also referred to as a chimney, is a mass of breccia (rock composed of broken fragments of minerals or rock cemented together by a fine-grained matrix), often in an irregular and cylindrical shape.
Fault breccia of the Keystone Thrust, Red Rock Canyon National Conservation Area, Nevada. Fault breccia, or tectonic breccia, is a breccia (a rock type consisting of angular clasts) that was formed by tectonic forces. Fault breccia is a tectonite formed by localized zone of brittle deformation (a fault zone) in a rock.
The composition of siliciclastic sedimentary rocks includes the chemical and mineralogical components of the framework as well as the cementing material that make up these rocks. Boggs divides them into four categories; major minerals, accessory minerals, rock fragments, and chemical sediments.
Conglomerate (/ k ən ˈ ɡ l ɒ m ər ɪ t /) is a sedimentary rock made up of rounded gravel-sized pieces of rock surrounded by finer-grained sediments (such as sand, silt, or clay). The larger fragments within conglomerate are called clasts, while the finer sediment surrounding the clasts is called the matrix.
Banded iron formation – Layered iron-rich sedimentary rock; Breccia – Rock composed of angular fragments; Calcarenite – Type of limestone that is composed predominantly of sand-size grains; Chalk – Soft carbonate rock; Chert – Hard, fine-grained sedimentary rock composed of cryptocrystalline silica
A pyroclastic rock containing 25–75% volcanic bombs and/or volcanic blocks is called tuff breccia. [4] Tuff composed of sandy volcanic material can be referred to as volcanic sandstone. [5] Tuff is a relatively soft rock, so it has been used for construction since ancient times. [6]
Impact breccia from the Kara impact structure in Russia. Breccia is "a rock consisting of angular fragments cemented together". [6] An impact breccia is formed when a meteor shatters a rock and then cements it back together. Some breccias contain impact melts. [3]