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Related to breccia: Volcanic breccia


see conglomerateconglomerate,
in geology, sedimentary rock composed largely of pebbles or other rounded particles whose diameter is larger than 2 mm (.08 in.). Essentially a cemented gravel, conglomerates are formed along beaches, as glacial drift, and in river deposits.
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cemented rock composed of angular fragments (sized 1 cm or more). Breccias may be composed of fragments from one rock (monomictic breccia) or several different rocks (polymictic breccia).

Breccias are volcanic (volcanogenic), sedimentary, or tectonic in origin. Volcanogenic breccias originate when the more liquid lava cements together the lava fragments which have formed during the crushing and breakdown of flowing viscous lava (lava breccia), during the agglomeration of tuff and other volcanogenic elastic materials (tuff breccia), and during the diagenesis of mud flow deposits in volcanic regions (lahars). Sedimentary breccias are formed in continental conditions during the cementation of talus deposits and mud-flow deposits from lahars, and during the collapse of the roofs of karstic cavities (karst breccia). A specific type of breccia is bone breccia, which originates in places where the mass destruction and burial of vertebrates has occurred. In maritime areas breccia originates as a result of the destruction of littoral rocks or reefs. Tectonic breccias (friction breccia) are formed in a rock stratum during tectonic movements when rock is crushed along the fractures. Large fragments in this case are usually buried in a finely granulated mass.



A rock made up of very angular coarse fragments; may be sedimentary or may be formed by grinding or crushing along faults.


Any stone composed of angular fragments embedded and consolidated in a finer ground. Numerous marbles owe their distinctive appearance to brecciation.
References in periodicals archive ?
The fragmental breccia is moderately to strongly altered and infused with finely disseminated pyrite (iron sulfide) in the breccia matrix, in the breccia fragments and in cross cutting veinlets.
The purpose of this drilling is to define the breccia pipe or pipes so that the center can be accurately defined and then the drill will be moved to the center where the pipe is tested at a depth where ore is expected, about 900 to 1,500 feet below the current surface.
Tom Richards, BSc, PhD: "La Negra is a classic Diatreme Breccia prospect and an entirely new grass roots silver discovery.
A breccia pipe is a vertical pipe-like column of broken rock, which, because of the coarse-grained and initially porous nature of these breccia pipes, allowed mineralizing fluids that passed through some pipes to deposit a large suite of metallic minerals.
In hand specimen, leached, oxidized, and sheared San Diego breccia consists of cobble to boulder sized, sub-rounded aphanite clasts in a dark gray, amorphous silica matrix.
The Twilight Zone breccia and San Pedro breccia are mineralized zones within and adjacent to granodiorite igneous rocks, thus there is an important relationship between the sedimentary rocks, veins, breccias and intrusive rocks at Vianey Mine.
Within EL 23121, four diamonds were reported in the northern part within streams transecting the main Merlin NNE structure containing the recently tested Perceval breccia at the Merlin Diamond Mine by North Australian Diamonds Limited.
It is in one of the most prolific breccia pipe areas in the NPSP with several breccia pipes per square mile (owned by the Company) over an adjacent area of about 14 square miles.
9 square miles in 5 blocks including 20 new uranium breccia pipe targets (Pipes).
4 square miles in 4 blocks including 16 new uranium breccia pipe targets (Pipes).
The primary target is an intrusive-related breccia pipe hosting copper-gold mineralization.