Close-up of rusty schist outcrop on the eastern slope of Mount Tom in Connecticut, where the rocks have been estimated to be 1.3 billion years old. Schist is a metamorphic rock formed from tremendous pressure and heat. It constitutes much of the bedrock in this area and often contains iron, hence the rusty surfaces. This rock is similar to the Manhattan schist found in New York City's Central Park. The thin layering of schist, or foliation, means it can cleave along the planes of foliation to form flat, sheet-like surfaces. Strength | Toughness | Rusty | History | Nature