Chlorite

"Chlorite" is the name of a group of common sheet silicate minerals that form during the early stages of metamorphism. Most chlorite minerals are green in color, have a foliated appearance, perfect cleavage, and an oily to soapy feel. They are found in igneous, metamorphic and sedimentary rocks. Chlorite minerals are found in rocks altered during deep burial, plate collisions, hydrothermal activity, or contact metamorphism. They are also found as retrograde minerals in igneous and metamorphic rocks that have been weathered. Rocks that commonly contain abundant chlorite include greenschist, phyllite, chlorite schist, and greenstone. https://www.mindat.org/min-1016.html https://geology.com/minerals/chlorite.shtml