Search results
Results From The WOW.Com Content Network
These structures are lighter colored than the host rock and typically range in diameter from 0.05mm to over 5 cm. [1] [2] [3] In 1648, Aldrovandi created the term variolite for aphanitic or fine-grained igneous rocks containing varioles. [4] [5] The weathering of varioles often cause variolites to have a pock-marked appearance.
Granodiorite (/ ˌ ɡ r æ n oʊ ˈ d aɪ. ə r aɪ t, ˌ ɡ r æ n ə ˈ-/ GRAN-oh-DY-ə-ryte, GRAN-ə-) [1] [2] is a coarse-grained intrusive igneous rock similar to granite, but containing more plagioclase feldspar than orthoclase feldspar. The term banatite is sometimes used informally for various rocks ranging from granite to diorite ...
Labradorite occurs in mafic igneous rocks and is the feldspar variety most common in basalt and gabbro. The uncommon anorthosite bodies are composed almost entirely of labradorite. [ 4 ] It also is found in metamorphic amphibolites and as a detrital component of some sediments.
Trachyte – Extrusive igneous rock – A silica-undersaturated volcanic rock; essentially a feldspathoid-bearing rhyolite; Troctolite – Igneous rock – A plutonic ultramafic rock containing olivine, pyroxene and plagioclase; Trondhjemite – Light-colored intrusive igneous rock – A form of tonalite where plagioclase-group feldspar is ...
Monzonite is a coarse-grained igneous rock. Such rocks are classified by their relative percentages of quartz, plagioclase, alkali feldspar, and feldspathoid (the QAPF classification). Monzonite is defined as rock having less than 5% quartz in its QAPF fraction and in which alkali feldspar makes up between 35% and 65% of the total feldspar content.
These rock types can include: Mangerite: a pyroxene-bearing monzonite intrusive igneous rock; Charnockite: an orthopyroxene-bearing quartz-feldspar rock, once thought to be intrusive igneous, now recognized as metamorphic; Iron-rich felsic rocks, including monzonite and rapakivi granite; Iron-rich diorite, gabbro, and norite
Metamorphic rocks are formed by subjecting any rock type—sedimentary rock, igneous rock or another older metamorphic rock—to different temperature and pressure conditions than those in which the original rock was formed. This process is called metamorphism, meaning to "change in form". The result is a profound change in physical properties ...
Extrusive rock refers to the mode of igneous volcanic rock formation in which hot magma from inside the Earth flows out (extrudes) onto the surface as lava or explodes violently into the atmosphere to fall back as pyroclastics or tuff. [1] In contrast, intrusive rock refers to rocks formed by magma which cools below the surface. [2]