Which magma type tends to have the highest viscosity, mafic or felsic?

Answer 1

Because mafic magmas and lavas are very hot, their melts tend to be relatively runny. At high temperatures, more bonds between atoms break and atoms vibrate more from the heat and spread further apart, which result in a liquid that is runnier and less viscous. The low viscosity of mafic melts often causes mafic volcanoes to be broad and short. The silica tetrahedra in mafic melts also tend to be isolated or occur in thin chains, which further contribute to low viscosity.

Mafic melts are hot and have relatively low viscosity:


In contrast, felsic magmas and lavas are relatively cool and may contain partially solidified materials. Because silica is so abundant (65-75%) in felsic melts, the silica tend to form silicate minerals with three-dimensional silica networks, such as quartz and feldspars. Because of lower temperatures (600-900oC), the presence of three-dimensional silica, and possible partial solidification, felsic lavas and magmas tend to be very "sticky" or viscous.
Specifically, a felsic magma at 600oC is about 100,000 times more viscous than a felsic magma at 900oC. The high viscosities of felsic and intermediate extrusives produce steep volcanic cones like Mt. Rainier or the Soufriere Hills volcano.

Viscosities of mafic, dry felsic and wet felsic melts.

Answer 2

Low Viscosity Magma

Answer 3

High Viscosity Magma

Answer 4

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RE:
Which magma type tends to have the highest viscosity, mafic or felsic?

Answer 5

Felsic magma are very viscous due to their high silica content.

Mafic magmas are "runny" and produce large shield volcanoes, like Hawaii.

Answer 6

magfic