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.