Gneiss (pronounced (nice) is a foliated metamorphic rock characterized by distinct banding or layering, caused by the segregation of light- and dark-colored minerals. Appearance * Shows alternating light and dark bands * Light bands:mostly ,quartz and feldspar* * Dark bands: contain biotite, hornblende, or pyroxene * Often coarse-grained and very hard. Formation (Metamorphism) Gneiss forms through: 1. Regional metamorphism: deep burial and compression over large areas, such as mountain belts. 2.

Acasta Gneiss: this polished sphere is a sample from the oldest known rock formation on Earth- rocks from this area are dated as old as 4.03 billion years old based on multiple and mutually consistent radiometric dating techniques. This gneiss is only found in the Northwest Territories of Canada and was collected by Yellowknife resident Mark Brown. Happy Earth Day 2024! ➡️ Follow the link in my profile for info on how to obtain a chunk of the oldest piece of Earth for yourself (and many other sc