Link to USGS home page.
USGS HOME
Contact USGS

Facebook Icon Twitter Icon
  • Assess
  • Prepare
  • Forecast
  • |
  • Activity
  • Products
  • Observatories
  • About

Glossary - Mafic

Mafic

Describes magma that contains lower amounts of silica and is generally less viscous and less gas-rich than silicic magma. Tends to erupt effusively, as lava flows. Includes andesites (57-63 percent SiO2), basaltic andesites (53-57 percent SiO2), and basalts (47-53 percent SiO2).


Glossary Terms


A
B
C
D
E

F
G
H
I
K
L
M
O
P

Q
R
S
T
U
V