What type of rock is biotite gneiss?
This rock is mostly composed of creamy-white feldspar and quartz, together with dark minerals, of which the most abundant is the dark mica biotite. The dark minerals are arranged in a streaky banding, giving the rock a gneissic texture.
What is biotite gneiss used for?
Ornamental Stone Metamorphic Gneiss has many uses as a building material such as flooring, ornamental stones, gravestones, facing stones on buildings and work surfaces.
Is biotite a sedimentary gneiss?
Gneiss rocks may also be named after a characteristic component such as garnet gneiss, biotite gneiss, albite gneiss, and so forth. Orthogneiss designates a gneiss derived from an igneous rock, and paragneiss is one from a sedimentary rock.
What is the subclassification of gneiss?
Gneiss (Figure 10.17) forms at the highest pressures and temperatures, and has crystals large enough to see with the unaided eye. Gneiss features minerals that have separated into bands of different colours. Figure 10.17 Gneiss, a coarse-grained, high grade metamorphic rock, is characterized by colour bands.
What is banded gneiss?
gneiss, metamorphic rock that has a distinct banding, which is apparent in hand specimen or on a microscopic scale. Gneiss is medium- to coarse-grained and may contain abundant quartz and feldspar, which some petrographers regard as essential components.
What is characteristic of gneiss?
Gneiss is a medium- to coarse-grained, semischistose metamorphic rock. It is characterized by alternating light and dark bands differing in mineral composition (coarser grained than schist). The lighter bands contain mostly quartz and feldspar, the darker often contain biotite, hornblende, garnet or graphite.
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.
How is augen gneiss formed?
Feldspar, quartz, and garnet are common minerals which form augen. Augen form in rocks which have undergone metamorphism and shearing. This derives a form of shear direction information. A metamorphic rock which is clotted with augen is often called an augen gneiss.
How do you identify gneiss?
gneiss, metamorphic rock that has a distinct banding, which is apparent in hand specimen or on a microscopic scale. Gneiss usually is distinguished from schist by its foliation and schistosity; gneiss displays a well-developed foliation and a poorly developed schistosity and cleavage.
Where is gneiss most commonly found?
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.