Tuff is a type of consolidated rock composed primarily of volcanic ash. It is formed when layers of fine volcanic ash deposit accumulate and undergo subsequent lithification, often resulting from rapid cooling of pyroclastic material. The resulting rock is characteristically porous and relatively lightweight compared to much denser volcanic materials like basalt flows. The specific mineralogy and texture of the tuff depend on the composition of the source ash and the conditions of its deposition and subsequent diagenesis. Geologically, the presence and characteristics of tuff layers provide valuable data regarding past eruptive history and regional volcanism.