Pyroclastics; Tephra

Table 1 Types of volcaniclastic rocks

Type	Fragment form	Name of deposit	Appearance	Internal structure	Size	Rock
Fragments of consolidated rock	Hard rock	Hard	No definite shape	Indefinite structure	>50 mm	Agglomerate
					50–2 mm	Breccia
					<2 mm	Lithic fragment
				Porous structure	Indefinite	Pumice, scoria
Fragments in molten state	Unconsolidated to semi- consolidated magma	Plastic	Definite shape	Definite structure	>2 mm	Magma fragment
		Plastic	Definite shape	Definite structure	<2 mm	Plastic vitric fragment
		Semi-plastic to hard	Definite shape	Definite structure	Generally small	Vitric fragment
Crystalline mineral fragment	Hard mineral	Hard	Indefinite shape	Indefinite structure	Indefinite	Crystal fragment
Aggregate of pyroclastics	Hard pyroclastic aggregate	Solidified to semi-solidified	Indefinite shape	Indefinite structure	Indefinite	Volcanic ash ball
	Plastic pyroclastics	Solidified to semi-consolidated	Definite shape	Definite structure	Indefinite	Hot volcanic ash ball
						Volcanic dust