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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 drillhole intersected brecciated and faulted diorite, propylitic altered, and containing quartz-carbonate-pyrite-chalcopyrite veinlets at upper levels with an increase of massive sulphides and copper-gold grades at depth as reported in Table 1.
The first stage will entail moving the drill on site, sampling the brecciated zones, recovering soil samples and core drilling a sample grid over a length of approximately 1000 meters.
The best gold grades are confined within brecciated and altered dolerite with felsic porphyry intercalation and grey quartz vein with fine disseminated pyrite.
At Planalto, the survey has identified a number of coincident high resistivity and chargeability targets that underlay the silica veined and brecciated rock that has been mapped on surface for a distance of over 2 km.
The epithermal mineralization lies within an argillized and brecciated shear zone between two semi parallel faults within a volcano-sedimentary sequence.
Nearly all of the rock samples containing 50 ppb gold or higher are characterized by fractured to brecciated quartzite with introduced silica.
The mineralization is associated with stockwork type veins in brecciated dolomite or siltstone host rock.
The newly discovered, polymetallic base and precious metal deposit is characterized by intrusives, oxidized brecciated cappings derived from copper sulfides, intense silicification and sericite alteration, a pyritic halo and peripheral skarn type mineralization.
Here, a large 3 kilometer zone of sheared and brecciated silicious basalts and sediments occurs that may be analogous to the nearby Ulu deposit.
The silver ore occupies the top fifty feet of brecciated Guillmette Limestone along the axis and flanks of a north trending assymetrical anticline.
Silicified and brecciated outcrops on White Goat range up to 30 m wide.
The San Jose prospect is comprised of potassically altered intrusive cross-cut and brecciated by predominantly specular hematite breccias containing abundant copper-oxide.