Pyroclastic Material
Ash, Lapilli, Lava Blocks

Introduction
There are many kinds of pyroclastic material ejected during a volcanic eruption. Ash is the most common pyroclastic rock material ejected during an eruption. Volcanic ash is so fine that it can be blown into the atmosphere and picked up by the jet stream where it can circle the Earth for several years.

Kilauea volcano erupting pyroclastic material, HVO-USGS

Kilauea volcano eruption creating lava rocks, HVO-USGS

Pumice
Pumice is light-colored igneous rock blown into the air in a semi-liquid state. The rock cools so fast it does not have time to crystallize. Gas bubbles inside the molten lava expands producing a rock that resembles a sponge.

Floating rocks
Pumice is often buoyant enough to float and has been known to float for thousands of miles after a major eruption. It is often found on the shores of volcanic islands thousands of miles from the eruption.

Lapilli
Lapilli are pea-size to walnut-sized pieces of volcanic rock. All types of lava produces lapilli. Shield volcanoes, cinder cones, and composite volcanoes all produce lapilli

Lava bombs
Lava bombs are volcanic rocks larger than 64 mm in size. Lava bombs leave a volcano vent as glowing semi-molten rock fragments. While airborne lava bombs become streamlined forming aerodynamic shapes.

Violent volcanic eruptions
Lava blocks are often produced during violent volcanic eruptions when pieces  of a volcano are blown away. The rock fragments are greater than 64 mm in size with no upward limit to their size.

Lava blocks
Lava blocks are large pieces of rock blown out of a volcano which have angular shapes and are solid. Some lava blocks are pieces of the volcano vent or sides of the volcano when it blows apart. The pieces can be as big as a small car.  Lava blocks are the largest pieces of  pyroclastic material ejected during a violent eruption.

More Rock Cycle Links

Organic Rocks Learn how animals extract calcite out of ocean water to form shells that are organic rocks.

Limestone Caverns Learn how limestone caverns form and where you can visit some of them.

Basalt Rocks Basalt rocks cover the floors of all the oceans, create cinder cones and form the largest volcanic mountains on Earth.

Salt Domes Learn more about how salt domes form, what they are used for and how they are sometimes a key to find oil.


Lava Caves Find out how pahoehoe lava flows form lava caves.

Pyroclastic Material This page gives all kinds of information about volcanic material that forms during volcanic eruptions.

Rock Cycle Learn more about igneous, sedimentary and metamorphic rocks and how they form.

Kids Fun Science The links on our home page include information about volcanoes, science activities, plate tectonics, the rock cycle and much more.