A crystalline rock, consisting, like granite, of quartz, feldspar, and mica, but having these materials, especially the mica, arranged in planes, so that it breaks rather easily into coarse slabs or flags. Hornblende sometimes takes the place of the mica, and it is then called hornblendic gneiss or syenitic gneiss. Similar varieties of related rocks are also called gneiss.
A name applied to a broad group of rocks. Generally speaking gneisses are banded rocks formed during high-grade regional metamorphism
a metamorphic rock that resembles granite. "Metamorphic rock" is rock that has been changed by heat or pressure. Herbaceous: a plant that has little or no woody tissue and is instead soft and green.
A coarsely laminated or foliated metamorphic rock corresponding in composition to granite or other coarse grained igneous rocks containing feldspar.
a high grade metamorphic rock with well developed lineation or foliation, typically granitic in composition.
A banded metamorphic rock. Note that the bands only rarely relate to structure (e.g. bedding) within the original (pre-metamorphic) rock - they form due to mineral segregation during metamorphism and or concurrent deformation.
This is a type of metamorphic rock. In the Knockan Crag area it is known as Lewisian gneiss after Lewis in the Outer Hebrides, as the island is almost entirely made of this old hard rock. These Lewisian gneisses are some of the oldest rocks in the World; they have been aged at between 3200 million and 2800 million years old. They were originally layers of sedimentary rocks, like sandstone and mudstone, interspersed with layers of volcanic rock, which have experienced very high temperatures and pressures deep in the Earthâ€™s crust.
A coarse-grained, foliated rock produced by regional metamorphism. The mineral grains within gneiss are elongated due to pressure and the rock has a compositional banding due to chemical activity.
A coarse-grained metamorphic rock with a characteristic type of foliation (gneissic layering), resulting from alternating layers of light-colored and dark-colored minerals. Its composition is generally similar to that of granite.
a crystalline rock that is similar to granite.
A layered or banded crystalline metamorphic rock, the grains of which are aligned or elongated into a roughly parallel
Medium- to coarse-grained metamorphic rock in which bands of granular minerals alternate with bands of elongated minerals.
Generally a coarse grained banded crystalline metamorphic rock which has been subject to high temperatures and pressures.
A hard, coarse-grained, foliated (banded), metamorphic rock (altered by great temperature and/or pressure) of quartz, feldspar and mica; often has low water yield.
metamorphic rock displaying banding
A rock which consists essentially of the same, elements as granite, but having the mica disposed in parallel planes, producing a moderate tendency to cleavage into thick slabs. [Also called "Banded Granite," "Bastard Granite," and "Foliated Granite."
Light and dark, medium- to coarse-grained metamorphic rock characterized by compositional banding of light and dark minerals, typically composed of quartz, feldspar, and various amounts of dark minerals; occurs with a variety of compositions and is a characteristic rock of the uplands.
A term for a common category of metamorphic rocks in which heat and pressure have rearranged the minerals into planar compositional bands. Commonly, though by no means always, the minerals are dominantly quartz and feldspar, making a quartzo-feldspathic gneiss. The planar compositional bands define the rock's foliation.
nice” hard igneous rock; Minnesota's Gneiss is some of the world's oldest.
A coarse-grained metamorphic rock, with compositional layering and alignment of minerals, produced under conditions of regional high pressure.
A coarse-grained regional metamorphic rock that shows banding and parallel alignment of minerals.
High grade, coarse grained metamorphic rock with an overall composition similar to granite.
a variety of rocks with a banded or coarsely foliated structure formed by regional metamorphism
a laminated metamorphic rock similar to granite
a metamorphic rock that has a coarse-grained foliation of mineral grains, which is usually the result of an episode of regional metamorphism (e
a rock consisting of alterna
a rock consisting of alternating bands of light and dark minerals
metamorphosed coarse grained igneous rock. In this rock you get the recrystallization of quartz, feldspars, micas and amphiboles into bands.
A metamorphic rock, that may have been granite, that is an igneous rock; but heat and pressure have changed it.
A banded metamorphic rock. The principal minerals in gneiss are usually feldspar, quartz, and mica.
A coarse-grained rock in which bands rich in granular materials alternate with bands of mainly metamorphic rock.
Rock. A coarse-grained metamorphic rock that shows layering of minerals.
A metamorphic rock with a banded or coarsely foliated structure; often called â€œTrade Graniteâ€.
It is a banded or layered metamorphic rock, which is similar to the composition of granite.
a coarse-grained metamorphic rock, often banded or foliated, which represents the last stage in the metamorphism of rocks prior to melting; from Old German ganeist 'spark', related to Old Norse gneista 'to give off sparks'.
A foliated metamorphic rock corresponding in composition to a feldspathic plutonic rock (as granite).
A metamorphic rock that shows foliation in the form of bands of light and dark crystals.
A coarse-grained, foliated metamorphic rock marked by bands of light-colored minerals such as quartz and feldspar that alternate with bands of dark-colored minerals. This alternation develops through metamorphic differentiation.
Banded pressure altered rock
A banded metamorphic rock rich in quartz and feldspar and formed under high temperature and pressure.
A type of metamorphic rock formed as older rocks recrystallize under heat and stress from pressure chactorized by a layering of light and dark bands or streaks.
Metamorphic rock with bands or or streaks.
A coarse-grained, foliated metamorphic rock that commonly has alternating bands of light and dark-colored minerals.
A banded metamorphic rock. It may be produced by the heating and squeezing of a granite (Image).
a coarse, foliated metamorphic rock in which bands of granular minerals (commonly quartz and feldspars) alternate with bands of flaky or elongate minerals (e.g., micas, pyroxenes). Generally less than 50% of the minerals are aligned in a parallel orientation
a course-grained layered rock that alternates between granular minerals and schistose minerals.
A coarse-grained metamorphic rock having banding of alternate light and dark minerals (gneissosity).
a foliated (layered) rock formed by high temperature and high pressure regional metamorphism in which bands or thin lenses of granular minerals al-ternate with bands or thin lenses of minerals with flaky and/or elongate, tabular shapes. Often the alternating bands are of different colors. Often the rock is com-posed of orthoclase, quartz, and biotite, but composition is not an essential factor in its definition.
When a clay is metamorphosed under extreme conditions of heat and pressure a very small percentage of the rock may start to melt and this helps the new minerals forming in these conditions to segregate into bands. A typical gneiss may at first glance resemble a granite, but the minerals form distinct dark and light folded and swirling bands. Gneiss is typical of the ancient hearts of continents, and is found in Britain mainly in the extreme north-west of Scotland and on the Outer Hebrides. The 'Lewisian Gneiss' of this area is by far the oldest rock in Britain.
Coarse-grained metamorphic rock with discontinuous foliation caused by planar alignment of platy and lath-shaped minerals.
Metamorphic rock that forms when sedimentary or igneous rock is subjected to high temperatures and pressures. Granite often becomes gneiss rock.
A laminated metamorphic rock, the main bedrock of the Bronx.
A metamorphic rock that is distinguished by alternating bands or lenses of granular minerals (like quartz) and bands or lenses of flaky or elongate prismatic minerals (like mica or amphibole). Gneiss is formed under the high pressure and temperature of regional metamorphism.
A rock with alternating bands of granular and flaky (or elongate) minerals. Generally less than 1/2 the minerals show a preferred parallel orientation.
(150) - Metamorphic rock that exhibits alternating bands of lighter minerals (quartz, feldspars) and darker minerals (biotite, hornblende, pyroxene).
A layered metamorphic rock. Pronounced "nice."
a banded or foliated metamorphic rock, usually of the same composition as a granite - BACK granite- a common, coarse-grained hard igneous rock consisting chiefly of quartz, orthoclase or microcline and mica, used for building - BACK
a coarse-grained metamorphic rock composed of thin layers of minerals, usually feldspar and quartz
granular metamorphic, mesozonal rock composed of quartz, feldspars, micas, amphibole. Paragneiss: rock deriving from sediments; Orthogneiss: rock deriving from eruptive rocks
A form of granite, but having the component materials, especially the mica, arranged in planes so that it breaks rather easily into coarse slabs or flags.
A rock approaching granite in composition, but more or less laminated, and really produced by the alteration of a sedimentary deposit after its consolidation. 87
A foliated rock formed by regional metamorphism, in which bands of granular minerals alternate with bands of minerals having platy or elongate prismatic habits.
A metamorphic rock, commonly rich in quartz and feldspar, with a banded and foliated texture, formed at temperatures above about 550° Centigrade
a coarse-grained metamorphic rock characterised by a compositional banding.
Metamorphic granitelike rock showing layers.
A coarse-grained metamorphic rock, where the minerals occur in bands. Some gneisses are produced by the regional metamorphism of an original shale or mudstone; others represent igneous rocks that have been metamorphosed.
A stone in which the materials of which it is composed (quartz, feldspar and mica) are segregated in layers.
Metamorphic rock, showing distinct banding of light and dark minerals. Usually made of feldspars, micas and hornblende. read more
A type of granite in which the minerals have been aligned in a series of bands.
any of various regional metamorphic rocks consisting of coarse layers of quartz and feldspar alternating with layers of mafic minerals. [AHDOS
Gneiss (IPA: ) is a common and widely distributed type of rock formed by high-grade regional metamorphic processes from preexisting formations that were originally either igneous or sedimentary rocks. Gneissic rocks are coarsely foliated and largely recrystallized but do not carry large quantities of micas, chlorite or other platy minerals. Gneisses that are metamorphosed igneous rocks or their equivalent are termed granite gneisses, diorite gneisses, etc.