The composition of the magma affects the style of eruption. Basaltic magmas tend to form volcanoes that produce large volumes of lava, but small amounts of volcanic ash. Volcanoes with more silicic magma are much more explosive, with large amounts of the molten rock being ejected from the volcano as particulate matter. The particles ejected are known as pyroclastic material, also collectively referred to as tephra. Note that the term pyroclastic is used for material ejected from the volcano as particles and volcaniclastic refers to any deposit that is mainly composed of volcanic detritus. Pyroclastic material may be individual crystals, pieces of volcanic rock (lithic fragments), or pumice, the highly vesicular, chilled, ‘froth’ of the molten rock. The size of the pyroclastic debris ranges from fine dust a few microns across to pieces that may be several metres across