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Lapilli identification and geology

Pyroclastic fragments ejected during a volcanic eruption that range in size from 2 to 64 mm in diameter, intermediate between volcanic ash <2 mm and volcanic bombs/blocks 64 mm . Lapilli can be solid rock fragments from the vent walls lithic lapilli or vesicular blobs of molten lava that solidify in flight scoria or pumice lapilli . Accumulated lapilli deposits lithify into lapillistone. Field: volcanology. Example: The accretionary lapilli found in distal pyroclastic fall deposits from the eruption of Mount Mazama Crater Lake formed when ash particles aggregated around moisture nuclei during atmospheric transport.. Related terms: Pyroclastic, Ash, Volcanic bomb, Tuff.

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  • Pyroclastic
  • Tuff

Sources, scope & corrections

These authoritative resources support category-level nomenclature, terminology, identification methods, and safety. When a specimen-specific safety warning appears, the public-health source listed here directly supports that precaution. They are not line-by-line citations for every other property on this entry, and natural specimens vary.

Editorial owner
GeoMiner
Last updated
2026-03-30T15:19:42.027557+00:00
Review status
Published; not independently peer-reviewed
  • USGS Thesaurus — U.S. Geological Survey. Controlled earth-science terminology used to describe USGS information resources.
  • Glossary of Geologic Terms — U.S. National Park Service. Geologic definitions prepared by the NPS Geologic Resources Inventory.

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Common questions

What does Lapilli mean in geology?
Pyroclastic fragments ejected during a volcanic eruption that range in size from 2 to 64 mm in diameter, intermediate between volcanic ash <2 mm and volcanic bombs/blocks 64 mm . Lapilli can be solid rock fragments from the vent walls lithic lapilli or vesicular blobs of molten lava that solidify in flight scoria or pumice lapilli . Accumulated lapilli deposits lithify into lapillistone.
What is an example of Lapilli?
The accretionary lapilli found in distal pyroclastic fall deposits from the eruption of Mount Mazama Crater Lake formed when ash particles aggregated around moisture nuclei during atmospheric transport.
Which earth-science field uses the term Lapilli?
Lapilli is used in volcanology.
Which terms are related to Lapilli?
Related terms in this reference are Pyroclastic, Ash, Volcanic bomb, Tuff.

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