What type of rock is an augen gneiss?
Augen gneiss: A medium- to coarse-grained, banded, regional metamorphic rock composed mainly of quartz and feldspar with hornblende and mica also present in variable quantities, and characterized by large ovoidal megacrysts of feldspar known as “augens” (derived from the German for “eyes”).
What is the Protolith of augen gneiss?
The protolith of gneiss may be an igneous rock, in this case it is called an orthogneiss. It forms probably because of shear in vicous granitic magma. In this sense it is similar to igneous rocks like granite and gabbro and not similar to related metamorphic rocks like schist and phyllite which are foliated.
Where is gneiss found naturally?
Gneisses result from the metamorphism of many igneous or sedimentary rocks, and are the most common types of rocks found in Precambrian regions. Gneiss is found in New England, the Piedmont, the Adirondacks, and the Rocky Mts. Some gneisses are used as facing stone on buildings.
What is Archean gneiss?
The Archean gneisses and schists, which are the oldest rocks of the Indian Shield, constitute a considerable area of Peninsular India. The extent of the Archean system is depicted as the dominant system of South India in the pictured Geological Map of India.
What does augen gneiss mean?
eyes
Augen gneiss, from the German: Augen [ˈaʊɡən], meaning “eyes”, is a gneiss resulting from metamorphism of granite, which contains characteristic elliptic or lenticular shear-bound grains (porphyroclasts), normally feldspar, surrounded by finer grained material.
What does Augen mean?
[ ou′gən ] A large mineral grain or grain cluster having the shape of an eye in cross-section and occurring in foliated metamorphic rocks such as schist and gneiss. Augens form when large mineral crystals are sheared and deformed during the process of metamorphism.
What is the parent rock of quartzite?
Quartzite is a metamorphic rock formed under moderate to high- grade metamorphism that exhibits both foliated and nonfoliated structure. The parent rock to quartzite is sandstone.
Who discovered gneiss rock?
Gneiss is a type of rock that has been metamorphosed (affected by intense heat and pressure) at depth in Earth’s crust. Geological Survey of Canada geologist Janet King discovered the Acasta Gneiss during fieldwork in 1983.
Can gneiss be pink?
Light-pink to gray, medium- to coarse-grained, foliated but generally massive or poorly layered granitic gneiss, composed of quartz, microcline, oligoclase, and either biotite or muscovite or both, also locally amphibole or epidote.
What does gneiss turn into?
Gneiss usually forms by regional metamorphism at convergent plate boundaries. It is a high-grade metamorphic rock in which mineral grains recrystallized under intense heat and pressure. Regional metamorphism can transform shale into slate, then phyllite, then schist, and finally into gneiss.
What is gneiss used for?
Metamorphic Gneiss has many uses as a building material such as flooring, ornamental stones, gravestones, facing stones on buildings and work surfaces.
What causes banding in gneiss?
The banding is usually due to the presence of differing proportions of minerals in the various bands; dark and light bands may alternate because of the separation of mafic (dark) and felsic (light) minerals. Banding can also be caused by differing grain sizes of the same minerals.
Warum sollten die Blitze im Auge auftreten?
Treten die Blitze im Auge deshalb auf, weil die Augen überanstrengt sind bzw. aufgrund von Stress und psychischer Belastung, ist es häufig bereits ausreichend, sich eine Pause zu gönnen. Entspannungsübungen wie Yoga oder autogenes Training sind also auch für die Augen von Vorteil.
Was sind Blitzen im Auge oder Augenflimmern?
Bei Blitzen im Auge bzw. Augenflimmern handelt es sich um ein äußerst unspezifisches Symptom, das auf eine Reihe von Erkrankungen oder gesundheitlichen Beschwerden hinweisen kann, die harmlos oder gefährlich sein können.
Was sind die Ursachen für Augenflimmern?
Der Schwund ist eine der häufigsten Ursachen für Augenflimmern, da durch die Verkleinerung des Glaskörpers ein Zug auf den Verbindungspunkten zur Netzhaut entsteht. Die Zugkraft wirkt auf die Netzhaut und erzeugt so auf mechanischem Weg kurze Reize, die vom Gehirn als Flimmern, Blinken oder Blitze im Auge interpretiert werden.
Was ist das Flimmern vor dem Auge?
Das Flimmern vor dem Auge ist keine eigenständige Krankheit, sondern tritt als Symptom unterschiedlichster Erkrankungen auf. Patienten umschreiben das Augenflimmern auch mit dem Gefühl, als würde man in eine Lichterkette schauen. Unsere Wahrnehmung von Sehstörungen kann sehr unterschiedlich ausfallen.