Volcanic eruptions not only shatter solidified rock into fragments, but also blast molten state magma into pieces. These materials are shot up the air. When they fall and settle on the ground they form different types of tephra.
Volcanic ash: <2mm minerals or volcanic glass.
Lapillus: 2-50 (64)mm rock fragments.
Agglomerates: >50 (64) mm rock pieces.
Pumice: Porous lava blocks; light in texture with concentrated pores; usually buoyant.
Scoria: Also porous lava blocks but the pore wall is thicker; usually not buoyant.
Author：司永超/Jessica
