Spall are fragments of a material that are broken off a larger solid body. It can be produced by a variety of mechanisms, including as a result of projectile impact, corrosion, weathering, cavitation, or excessive rolling pressure. Spalling and spallation both describe the process of surface failure in which spall is shed.
Spall from knapping obsidian arrowheads and other tools. These unique obsidians are found at Glass Buttes, Oregon.
A chunk of armour knocked from HMS New Zealand's 'X' turret during the Battle of Jutland on display at the Torpedo Bay Navy Museum in Auckland. Caption reads, "The chunk of armour plating you see here was gouged out of X turret by a German shell."
Desquamation of dunite boulder
Granite dome exfoliation
Corrosion is a natural process that converts a refined metal into a more chemically stable oxide. It is the gradual deterioration of materials by chemical or electrochemical reaction with their environment. Corrosion engineering is the field dedicated to controlling and preventing corrosion.
Corrosion on exposed metal, including a bolt and nut
Galvanic corrosion of an aluminium plate occurred when the plate was connected to a mild steel structural support.
Gold nuggets do not naturally corrode, even on a geological time scale.
Normal microstructure of Type 304 stainless steel surface
