Search results
Results from the WOW.Com Content Network
Main page; Contents; Current events; Random article; About Wikipedia; Contact us
In geology, texture or rock microstructure [1] refers to the relationship between the materials of which a rock is composed. [2] 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 (in which crystals are not visible to the unaided eye ...
Examples of phaneritic igneous rocks are gabbro, diorite, and granite. Porphyritic textures develop when conditions during the cooling of magma change relatively quickly. The earlier formed minerals will have formed slowly and remain as large crystals, whereas, sudden cooling causes the rapid crystallization of the remainder of the melt into a ...
Porphyritic texture in a granite. This is an intrusive porphyritic rock. The white, square feldspar phenocrysts are much larger than crystals in the surrounding matrix; eastern Sierra Nevada, Rock Creek Canyon, California. A porphyritic volcanic sand grain, as seen under the petrographic microscope. The large grain in the middle is of a much ...
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.
Metamorphic rock naming can be based on protolith, mineral composition, texture, or metamorphic facies. Naming based on texture and a pelite (e.g., shale, mudrock) protolith can be used to define slate and phyllite. Texture-based names are schist and gneiss. These textures, from slate to gneiss, define a continually-increasing extent of ...
Examples include aquamarine, tourmaline, topaz, fluorite, apatite, and corundum, often along with tin, rare earth, and tungsten minerals, among others. [17] [3] Pegmatites have been mined for both quartz and feldspar. [26] For quartz mining, pegmatites with central quartz masses have been of particular interest. [26]
In nature, cumulates usually form from 2 mineral species, although ranges from 1 to 4 mineral species are known. Cumulate rocks which are formed from one mineral alone are often named after the mineral, for example a 99% magnetite cumulate is known as a magnetitite. A specific example is the Skaergaard intrusion in Greenland.