serpentinite
A green metamorphic facade stone composed mainly of serpentine minerals, often selected for its color and pattern.
Serpentinite is a dark green metamorphic rock, often formed in the oceanic crust or other deep geologic sources. It consists mainly of serpentine-group minerals formed through hydration of magnesium- and iron-bearing silicate minerals. Other constituents can include nickel, chromium, manganese, or cobalt.
The rock is named for serpents because of its green and often scaly appearance, although smoother and less scaly stones are much more commonly used in architecture. The rock gives buildings a distinctive appearance, and is favored for its aesthetic qualities.
The green color and surface pattern describe the natural stone. A smooth architectural finish does not exclude it merely because the surface lacks the scaly appearance that gave the rock its name.