Tuff is a type of rock that is formed from volcanic ash and other pyroclastic debris. It is a light and porous rock, often used as a building material due to its durability and insulation properties.
To be considered Tuff, the rock must contain more than 75% ash. 25-75% would be considered ‘tuffaceous’.
It can be formed by explosive volcanic eruptions or from the gradual accumulation of volcanic ash over time.
Tuff can be of interest to vulcanologists, as the layers of tuff can provide a record of volcanic activity over time.
Tuff should not be confused with tufa, a precipitated limestone.