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Breccia Rock

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Breccia rock is a clastic sedimentary rock made up of broken mineral fragments or rocks bonded together by a coarse-grained matrix that can be similar to or different from the composition of fragments.

The origin of the word "Beccia" is in Italian, language, in which it means broken stone, rubble. A breccia rock can have different sources, as represented by the named type including Impacts breccia, Sedimentary breccia, Igneous breccia, Hydrothermal breccia, and Tectonic breccia.

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Brecciated Meaning - Brecciated, similar to the breccia in appearance is a rock composed of angular fragments that are cemented together by a fine-grained matrix, that can be either small or different from the composition of fragments.

Breccia Rock Type

Breccia is a clastic sedimentary rock composed of angular or subangular fragments larger than 3 millimetres (0.8 inches). The breccia rock differs from conglomerate rock, which is composed of rounded clasts.

Breccia Formation

Breccia formation took millions of years. It forms where angular, broken fragments of mineral or rock deposits collect. The angular shape of the particles represents minimum transport. The breccia sedimentary rock generally forms as rock-falls and debris-flow deposits together with the cliffs, and underground along faults or where cave collapse and rock become cemented together by minerals over a long period. The type of rock formed in a specific location depends on the mineral fragments found in that area. The angular rock in the breccia can be easily seen with the naked eyes.

Breccia Types

Following are the different types of breccia sedimentary rock. 

Impact Breccia

Impact breccia is formed by the fracturing and fusion of rock under extreme pressure and temperature speedily induced during meteorite impacts. Impact breccia may be found on or below the crater, in the rim, or the ejecta evacuated beyond the crater.

The rock of this type may be recognized by its occurrence in or around a known impact crater and or in association with other products of impact cratering such as shattered stone, shocked minerals, impact glass, etc. An example of impact breccia is the Neugrad breccia, which was grounded in Neugrad impact.

Lunar Breccia

Lunar breccia is obtained by the smashing, melting, and mixing of the lunar surface material by large and small metric impact. Evidence of this process can be seen in the countless craters of different sizes which cover the moon.

Volcanic Breccia

Volcanic breccia is an extrusive igneous rock that is mainly composed of angular volcanic fragments resulting from brecciation or emplacement due to the volcanic eruption. This type of rock may or may not have a matrix. 

Tuff Breccia 

Tuff breccia is an extrusive igneous rock. The rock has a pyroclastic texture and is composed of coarse-grained fragments created during volcanic eruptions. The largest fragments less than 2.5 inches long are also observed in tuff breccia.

Limestone Breccia

A limestone breccia is a breccia that consists of clasts of varied types of limestone. The size of limestone breccia is about four inches (10 centimetres) across.

Fault Breccia

Fault breccia, also known as tectonic breccia is a breccia that was formed by tectonic forces along a localized zone of brittle deformation (a fault zone). The grinding and milling in fault zones occur when the two sides of the fault zone move along each other to obtain the material that is made up of loose fragments. Fault zones can be easily unfiltered by groundwater due to this fragmentation.

Fault Breccia Properties

  • It has no cohesion

  • It is usually an unconsolidated type of rock, as long as cementation occurs at a later stage.

  • Sometimes a differentiation is made between fault gauge and fault breccia. The fault gauge has a smaller grain size. 

Sedimentary Breccia

Sedimentary breccia is a type of  clastic sedimentary rock.The rock is composed of angular to sub-angular, randomly oriented clasts of other sedimentary rock. The rock such as sedimentary breccias is formed by either avalanche, submarine debris flow, mudflow, or mass flow in a liquefied medium. 

Sedimentary breccia consists of angular, poorly deposited, immature fragments of rock in finer graze grounds which are obtained by slope movement. Thick sequences of sedimentary breccia are usually formed next to the fault scabs in grabens.

Did You Know?

  • The breccia composition can be influenced by the climate.

  • Both breccia and conglomerate are made up of fragments having larger than 2 millimetres (0.079.in) in size.

  • The angular type of fragment in Breccia indicates that material has not been transported far from its origin.

  • The striking feature of breccia has made them popular sculpture and architectural material.

  • One of the best-known examples of breccia is the statue of the goddess Taweret in the British Museum.

  • Breccia stone was used by the Romans in high-profile public buildings.

  • A striking example of Breccia can be seen in the Pantheon in Europe.

  • Breccia rock can also be in different colours. The colour of the matrix or cement together with the colour of the rock fragments ascertain the colour of the Breccia.

  • Ejecta in impact breccia are the particles ejected from a particular area.

FAQ (Frequently Asked Questions)

Q1. What is the Similarity Between Breccia and Conglomerate?

Ans. Both Breccia and Conglomerate are clastic sedimentary rocks containing clasts larger than 2 mm in diameter. The difference between Breccia and Conglomerate is that clasts in Breccia are angular while those in Conglomerate are rounded. This represents that clasts in Conglomerate travelled at a greater distance from their source or experienced more weathering before becoming embedded in the matrix than the clasts in Breccia.

Q2. What are the different Uses of Breccia?

Ans. Due to the variable composition of Breccia, it has an attractive appearance. The breccia rock is primarily used to make sculptures, gems, and architectural elements. The ancient British use breccia rocks to make statues. The Romans used breccia to make public buildings, columns, and walls. In modern culture, breccia is used for making jewellery, decorative elements, and sometimes as fill màterials for roads.

Q3. What is a Megabreccia?

Ans. A megabreccia is made up of very large rock fragments, sometimes kilometres cross, which can be formed by landslides, impact events, and caldera collapse.