Volcanic rock (or
lava) that characteristically is light in color and contains 62 to 69
percent
silica
and moderate amounts of sodium and potassium.
Dacite
lavas are viscous and tend to form thick blocky lava flows or
steep-sided piles of lava called lava
domes.
Dacitic
magmas
tend to erupt
explosively, thus also ejecting abundant
ash
and
pumice.