Volcanic Ash


Volcanic ash is a mixture of rock, mineral, and glass particles expelled from a volcano during a volcanic eruption. The particles are very small—less than 2 millimeters in diameter. They tend to be pitted and full of holes, which gives them a low density. Along with water vapor and other hot gases, volcanic ash is part of the dark ash column that rises above a volcano when it erupts.

Due to their minuscule size and low density, the particles that make up volcanic ash can travel long distances. When an ash column is moved about by wind, it is called an ash plume. Eventually it falls to the ground creating a thick layer of dust-like material on surfaces for miles around the original eruption.

Its particles are very hard and usually have jagged edges. As a result, it can cause eye, nose, and lung irritation, as well as breathing problems. While in the air, ash can cause problems for jet engines, forcing airlines to cancel flights through the affected area. An ashfall that leaves a thick layer of ash may cause roofs to collapse, clog gutters, and interfere with air conditioning units. Animals in an area coated by volcanic ash may have difficulty finding food, as the plants in the region may be covered in ash. Ash can also contaminate water supplies.

Application and Uses

Instead of allowing ash to coat the environment where it poses risk, the naturally occurring pozzolan can be collected for use in cement, mortar and concrete.