Lava and ash

Lava is molten rock that a volcano expels during an eruption. Lava, when first exuded from a volcanic vent, is a liquid at very high temperature: typically from 700°C to 1200°C (1300°F to 2200°F). However, the viscosity of lava is 100,000 times that of water. Nevertheless, the viscous rock can flow many miles before eventually cooling and solidifying.

When a volcano erupts it sends out a variety of hot materials, including lava, tephra, ash and gases. Lava is hot molten rock from the Earth's interior. It is called magma while it is still underground.

Tephra is material blasted into the air by an eruption. It includes pyroclasts ( solid lava ) and volcanic bombs.

Pyroclasts are big chunks of volcanic rock that are thrown out by explosive volcanoes when the plug in the volcano's vent shatters. " Pyroclast " means fire broken. Pyroclasts are usually 0.3 - 1 m across.

Big eruptions can blast pyroclasts weighing 1 tonne or more up into the air at the speed of a jet plane. Cinders and lapilli are small pyroclasts. Cinders are 6.4 - 30 cm diameter; lapilli are
0.1 - 6.4 cm.

Volcanic bombs are blobs of molten magma that cool and harden in flight.

Breadcrust bombs are bombs that strech into loaf shapes in flight; gases inside them create a "crust".