In
geology
Geology () is a branch of natural science concerned with Earth and other astronomical objects, the features or rocks of which it is composed, and the processes by which they change over time. Modern geology significantly overlaps all other Ear ...
, texture or
rock microstructure
Rock microstructure includes the texture and small-scale structures of a rock. The words ''texture'' and ''microstructure'' are interchangeable, with the latter preferred in modern geological literature. However, ''texture'' is still acceptable ...
refers to the relationship between the materials of which a
rock
Rock most often refers to:
* Rock (geology), a naturally occurring solid aggregate of minerals or mineraloids
* Rock music, a genre of popular music
Rock or Rocks may also refer to:
Places United Kingdom
* Rock, Caerphilly, a location in Wales ...
is composed.
[ The broadest textural classes are crystalline (in which the components are intergrown and interlocking crystals), fragmental (in which there is an accumulation of fragments by some physical process), ]aphanitic
Aphanites (adj. ''aphanitic''; ) are igneous rocks that are so fine-grained that their component mineral crystals are not visible to the naked eye (in contrast to phanerites, in which the crystals are visible to the unaided eye). This geolog ...
(in which crystals are not visible to the unaided eye), and glassy (in which the particles are too small to be seen and amorphously arranged).[Texture & Genesis of Rocks, Introductory Geology Laboratory, Christopher DiLeonardo, Ph.D., Marek Cichanski, Ph.D., Earth & Space Sciences, ]De Anza College
De Anza College is a public community college in Cupertino, California. It is part of the Foothill-De Anza Community College District, which also administers Foothill College in nearby Los Altos Hills, California. The college is named after th ...
The geometric aspects and relations amongst the component particles or crystals are referred to as the '' crystallographic texture'' or ''preferred orientation''. Textures can be quantified in many ways.phaneritic
A phanerite is an igneous rock whose microstructure is made up of crystals large enough to be distinguished with the unaided human eye. In contrast, the crystals in an aphanitic rock are too fine-grained to be identifiable. Phaneritic texture fo ...
, foliated, and porphyritic.[ Phaneritic textures are where interlocking crystals of igneous rock are visible to the unaided eye. Foliated texture is where metamorphic rock is made of layers of materials.][ Porphyritic texture is one in which larger pieces (]phenocrysts
300px, feldspathic phenocrysts. This granite, from the Switzerland">Swiss side of the Mont Blanc massif, has large white plagioclase phenocrysts, triclinic minerals that give trapezoid shapes when cut through). 1 euro coins, 1 euro coin (diameter ...
) are embedded in a background mass made of much finer grains.[
Fragmental textures include clastic, ]bioclastic
Bioclasts are skeletal fossil fragments of once living marine or land organisms that are found in sedimentary rocks laid down in a marine environment—especially limestone varieties around the globe. some of which take on distinct textures and col ...
, and pyroclastic
Pyroclastic rocks (derived from the el, πῦρ, links=no, meaning fire; and , meaning broken) are clastic rocks composed of rock fragments produced and ejected by explosive volcanic eruptions. The individual rock fragments are known as pyroc ...
.[
A ]preferred mineral orientation
In geology, texture or rock microstructure refers to the relationship between the materials of which a rock is composed. The broadest textural classes are crystalline (in which the components are intergrown and interlocking crystals), fragmental ...
, is the texture of metamorphic rock
Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock (protolith) is subjected to temperatures greater than and, often, elevated pressure of or more, causin ...
in which its grains have a flattened shape (inequant), and their planes tend to be oriented in the same direction.[Essentials of Geology, 3rd Ed, Stephen Marshak]
See also
* List of rock textures
This page is intended to be a list of rock textural and morphological terms.
A
* Adcumulate
* Agglomeritic
* Adamantine a type of lustre
* Amygdaloidal
* Anhedral
* Antitaxial veins
* Aphanitic
* Aplitic; aplite
* Augen textured gn ...
* Rock microstructure
Rock microstructure includes the texture and small-scale structures of a rock. The words ''texture'' and ''microstructure'' are interchangeable, with the latter preferred in modern geological literature. However, ''texture'' is still acceptable ...
* Texture (crystalline)
In physical chemistry and materials science, texture is the distribution of crystallographic orientations of a polycrystalline sample (it is also part of the geological fabric). A sample in which these orientations are fully random is said to ha ...
* Igneous textures
Igneous textures include the rock textures occurring in igneous rocks. Igneous textures are used by geologists in determining the mode of origin of igneous rocks and are used in rock classification. The six main types of textures are phaneritic ...
* Vesicular texture
Vesicular texture is a volcanic rock texture characterized by a rock being pitted with many cavities (known as vesicles) at its surface and inside.
This texture is common in aphanitic, or glassy, igneous rocks that have come to the surface of ...
* Amygdule
Amygdules or amygdales () form when the vesicles (pores from gas bubbles in lava) of a volcanic rock or other extrusive igneous rock are infilled with a secondary mineral, such as calcite, quartz
Quartz is a hard, crystalline mineral c ...
* Soil texture
Soil texture is a classification instrument used both in the field and laboratory to determine soil classes based on their physical texture. Soil texture can be determined using qualitative methods such as texture by feel, and quantitative methods ...
References
Petrology
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