Sandgrube Engeln

Lapilli is a size classification term for thephra, which is material that falls out of the air during aVolcanic eruption. Lapilli (singular: lapillus) means "little stones" in Latin. They are in some senses similar to ooids or pisoids diameter. ^{A pyroclastic particle greater than 64 mm in diameter is correctly known as a volcanic bombs when molten, or a volcanic block when solid. Pyroclastic material with particles less than 2 mm in diameter is referred to volcanic ashes.}