|lapillus (lə-pĭl'əs) Pronunciation Key
Plural lapilli (lə-pĭl'ī')
A small fragment of lava, between 2 and 64 mm in size, blown out from a volcano.
unconsolidated volcanic fragment with a diameter between 4 and 32 mm (0.16 and 1.26 inches) that was ejected during a volcanic explosion. Lapilli may consist of fresh magma, solid magma from a prior eruption, or basement rocks through which the eruption passed. Accretionary lapilli are pellets formed by the accretion of volcanic ash or dust around moisture droplets; as in hailstones formed of water, these volcanic "hailstones" may show concentric rings-some as much as 10 cm (four inches) across-when they are carried through the eruption cloud several times by turbulent updrafts.
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