Pyroclastic fragments or tephra ranging in size from 2 to 64mm. Lapilli may be composed of primary magmatic material (e.g. pumice), accessory lithic material, accidental lithic material, or accretions of wet ash-size material (accretionary lapilli). The size-term ‘lapilli’ is usually applied to the lithological clast type to give descriptive terms, e.g. ‘pumice lapilli’ or ‘accessory lithic lapilli’.
Subjects: Earth Sciences and Geography.