One block of peridotite has white fibrous veins of asbestos in it. In some outcrops, the peridotite has weathered orange, from oxidation of iron. Rectangular vein patterns on some rocks come from serpentine formed in fractures. Shiny boulders of green and black are serpentine, many have grooves on the surface from fault scraping. Chert appears as light colored shiny boulders with hard layers.
Color ranges from white, to red, orange or dark green.
The red colors come from iron in various combinations with oxygen. Much of the silica comes from microscopic floating organisms called radiolaria. Silica is not abundant in sea water so it is a mystery how layers of chert form. When the volcanic eruption stops, the silica supply is cut off, the radiolaria die and fall to the bottom of the ocean to form chert. The presence of chert is further evidence that ocean floor has been plastered against the side of the continent and uplifted.