Muscovite
The most common form of mica found in rocks like gneiss, granite, and schist is biotite. Biotite is a dark-colored mica mineral that is often found in igneous and metamorphic rocks, imparting a shiny appearance to the rock surfaces. It is known for its thin, sheet-like structure and is commonly associated with other minerals in these types of rocks.
Gneiss rocks typically form from the metamorphism of either sedimentary rocks like shale or igneous rocks like granite. Through intense heat and pressure deep within the Earth's crust, the original minerals in these rocks recrystallize and reorganize to create the distinctive banding and foliation that characterizes gneiss.
Granite, sandstone, and shale transform into distinct metamorphic rocks under heat and pressure. Granite typically becomes gneiss, characterized by its banded appearance due to the alignment of mineral grains. Sandstone metamorphoses into quartzite, which is known for its hardness and resistance to weathering. Shale, on the other hand, transforms into schist or slate, depending on the degree of metamorphism, with schist displaying a foliated texture and slate exhibiting a more dense and compact structure.
Rocks such as gneiss and schist form under high temperature and pressure conditions found a few kilometers beneath the Earth's surface. These rocks are typically a result of metamorphic processes that alter existing rock types like granite or basalt.
Sandstone is changed into quartzite and basalt is changed into schist or gneiss through the process of metamorphism.
Gneiss may form from either granite or schist.
Gneiss could eventually form from granite or from schist.
Biotite is the most common form of mica.
muscovite
The most common form of mica found in rocks like gneiss, granite, and schist is biotite. Biotite is a dark-colored mica mineral that is often found in igneous and metamorphic rocks, imparting a shiny appearance to the rock surfaces. It is known for its thin, sheet-like structure and is commonly associated with other minerals in these types of rocks.
Granites can turn into metamorphic, sedimentary, or igneous rock through metamorphosis.
Gneiss is neither limestone nor sandstone. Gneiss is a metamorphic rock that forms from the transformation of pre-existing rocks such as granite or sedimentary rocks under high heat and pressure. The resulting gneiss typically exhibits banded layers of minerals.
A mixture of sand and clay, mudstone, metamorphose (process of changing from one type of rock into a metamorphic rock) into gneiss rocks or schist rocks. The mudstones would change under heat and pressure to make the new Metamorphic rocks.
Gneiss rocks form from the metamorphism of existing rocks, such as granite or sedimentary rocks, under high temperature and pressure conditions deep within the Earth's crust. This process causes mineral grains in the rock to recrystallize and rearrange, giving gneiss its characteristic banded appearance.
Gneiss is a metamorphic rock. It is formed form another metamorphic rock called schist (sh-ist). Schist is formed form fine grained sedimentary rock (often shale). While gneiss is formed by great pressure from moving plates of the earth's crust.
There is no grade of metamorphism beyond gneiss. Higher grades of metamorphism mean higher temperature and pressure. Beyond the conditions that form gneiss, temperatures are high enough to melt rock, at which point the resulting rock will be igneous rather than metamorphic.
Gneiss rocks typically form from the metamorphism of either sedimentary rocks like shale or igneous rocks like granite. Through intense heat and pressure deep within the Earth's crust, the original minerals in these rocks recrystallize and reorganize to create the distinctive banding and foliation that characterizes gneiss.