Gneiss (noun)

1. A type of metamorphic rock characterized by distinct bands of light and dark mineral grains, typically having a banded appearance.
2. A rock that has been metamorphosed, typically having a banded appearance.

Origin:

From german gneis, from middle high german gneis, from old high german gneist, from proto-germanic *gnīstaz ("spark, spark of fire"), from proto-indo-european *gneh₁- ("to spark, to glitter").

Examples:

1. Gneiss is a common rock type in the earth's crust.
2. The building stone is gneiss, a kind of granite with a more banded appearance.
3. The mountains around us are mostly composed of gneiss.
4. Gneiss is a medium to coarse-grained rock that is formed by the alteration of igneous rocks.
5. The rock is a coarse-grained gneiss containing large feldspar crystals.