What is greenschist?

Greenschist is a common type of metamorphic rock that forms from the alteration of basalt or other basic igneous rocks. It typically has a green color due to the presence of minerals such as chlorite, epidote, and actinolite. Greenschist is often found in regions of low-grade metamorphism, where rocks have been subjected to relatively low temperatures and pressures.

The mineral assemblage of greenschist is typically dominated by chlorite and actinolite, with lesser amounts of albite, epidote, and quartz. This assemblage is characteristic of the greenschist facies, one of the lower temperature and pressure metamorphic facies.

Greenschist is commonly used as a building material, especially for decorative purposes due to its attractive green color. It is also used in landscaping and as a facing stone for buildings. Additionally, the presence of certain minerals in greenschist can make it a potential source of valuable metals such as gold, silver, and copper.

Overall, greenschist is a significant and widely occurring type of metamorphic rock that plays an important role in the geological history of many regions.