Clays are stable under conditions at the Earth's surface Feldspars and clays are similar in composition. Feldspar readily alters to clay when in contact with acid and water. The order in which silicate minerals weather. Minerals which form at lower temperatures and pressures are most stable. The order of mineral stability in the weathering environment is the same order as Bowen's Reaction Series.
Weathered rock is called saprolite .
Weathered rock fragments are one of the constituents of soil . Quartz grains may be eroded, becoming sediment. Clays will ultimately be eroded and washed out to sea. A soil profile consists of several soil horizons . This is the layer of humus on the ground surface.