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  2. List of rock types - Wikipedia

    en.wikipedia.org/wiki/List_of_rock_types

    The following is a list of rock types recognized by geologists.There is no agreed number of specific types of rock. Any unique combination of chemical composition, mineralogy, grain size, texture, or other distinguishing characteristics can describe a rock type.

  3. Rock (geology) - Wikipedia

    en.wikipedia.org/wiki/Rock_(geology)

    The use of rock has had a huge impact on the cultural and technological development of the human race. Rock has been used by humans and other hominids for at least 2.5 million years. [22] Lithic technology marks some of the oldest and continuously used technologies. The mining of rock for its metal content has been one of the most important ...

  4. Clastic rock - Wikipedia

    en.wikipedia.org/wiki/Clastic_rock

    Clastic rocks are composed of fragments, or clasts, of pre-existing minerals and rock. A clast is a fragment of geological detritus , [ 1 ] chunks, and smaller grains of rock broken off other rocks by physical weathering . [ 2 ]

  5. Facies - Wikipedia

    en.wikipedia.org/wiki/Facies

    A facies encompasses all the characteristics of a rock including its chemical, physical, and biological features that distinguish it from adjacent rock. [ 2 ] The term "facies" was introduced by the Swiss geologist Amanz Gressly in 1838 and was part of his significant contribution to the foundations of modern stratigraphy , [ 3 ] which replaced ...

  6. Primary rock - Wikipedia

    en.wikipedia.org/wiki/Primary_Rock

    Primary rocks (geol.) a term early used for rocks supposed to have been first formed, being crystalline and containing no organic remains, as granite, gneiss, etc.; – called also primitive rocks. The terms Secondary, Tertiary, and Quaternary rocks have also been used in like manner, but of these the last two only are now in use.

  7. Rock cycle - Wikipedia

    en.wikipedia.org/wiki/Rock_cycle

    This diamond is a mineral from within an igneous or metamorphic rock that formed at high temperature and pressure. The rock cycle is a basic concept in geology that describes transitions through geologic time among the three main rock types: sedimentary, metamorphic, and igneous.

  8. Country rock (geology) - Wikipedia

    en.wikipedia.org/wiki/Country_rock_(geology)

    When describing a pluton or dike, the igneous rock can be described as intruding the surrounding country rock, the rock into which the pluton has intruded. [3]When country rock is intruded by a dike, perpendicular to the bedding plane, it is called discordant intrusion, while a parallel intrusion by a sill indicates a sub-parallel or concordant intrusion.

  9. Matrix (geology) - Wikipedia

    en.wikipedia.org/wiki/Matrix_(geology)

    Igneous rock, with gray groundmass and white phenocrysts marked. Orthoclase phenocrysts within a finer-grained matrix of a granite porphyry. The matrix or groundmass of a rock is the finer-grained mass of material in which larger grains, crystals, or clasts are embedded.