Is tuff a sedimentary or an igneous rock?

If you must simplistically classify all rocks as either sedimentary, igneous or metamorphic, then it is igneous. In fact, it is a sub-class of igneous rocks called pyroclastics. read more

Tuff is an igneous rock that forms from the products of an explosive volcanic eruption. In these eruptions, the volcano blasts rock, ash, magma and other materials from its vent. This ejecta travels through the air and falls back to Earth in the area surrounding the volcano. read more

Tuffs are (pyro)clastic rocks composed primarily of ash, pumice, and lithic fragments and can be classified as either sedimentary or igneous rocks as they can exhibit most of the characteristics of other clastic sedimentary rocks (bedding, fragments or foreign rocks, form from accumulation of discrete clasts rather than directly from a melt, etc) yet are formed as a direct result of igneous process. read more

Tuff is a relatively soft rock, so it has been used for construction since ancient times. Since it is common in Italy, the Romans used it often for construction. The Rapa Nui people used it to make most of the moai statues in Easter Island. Tuff can be classified as either sedimentary or igneous rock. read more