answersLogoWhite

0

Pumice is more related to a textural feature, rather than a compositional attribute. For example, pumice originates when there are enough dissolved gases in the magma, such that when it is ejected from the volcano, the depressurization of the dissolved gases causes a rapid expansion as the gases exsolve (just like when you open a pop - the gases are initially under pressure, and you release that pressure by opening the can or bottle). The rapid change in temperature, from hundreds to thousands of degrees to the temperature of of the surrounding environment, causes a rapid cooling effect, whereby the expanding gases are frozen in place. These two factors are what give pumice its distinctive texture and ability to float when placed in water, as opposed to other volcanic rocks (such as scoria).

Whether or not the pumice is felsic (light in color) or mafic (dark in color) depends on its chemical composition and therefore, pumice can be both felsic or mafic depending on its parental magma.

General classification as to whether a rock is felsic or mafic is with regards to the silicate content of the rock as follows:

felsic < 69% SiO2

Intermediate Felsic 63 - 69% SiO2

Intermediate 52- 63% SiO2

Mafic < 52% SiO2

Ultra Mafic < SiO2

This said, felsic pumice (white or light tan brown colors) are more common to find than mafic pumice.

User Avatar

Wiki User

14y ago

What else can I help you with?

Related Questions

Why are felsic rocks melted by mafic magmas but mafic rocks are not melted by felsic magmas?

Felsic rocks have a lower melting point than mafic rocks and felsic magma has a lower temperature. In other words, felsic magma is not hot enough to melt mafic rock while mafic magma is hot enough to melt felsic rock.


Is amphibolite mineral a felsic mafic or intermidate?

Is mineral amphibolite a felsic, mafic or intermidiate in term of color


Is the oceanic crust felsic or mafic?

Oceanic crust is mafic.


Is a limestone mafic?

No. The terms mafic and felsic apply to igneous rocks. Limestone is a sedimentary/biochemical rock and so cannot be said to be mafic, felsic, or intermediate.


Is sandstone felsic or mafic?

Neither. The terms mafic and felsic refer to the composition of igneous rocks, which are dominated by silicate minerals. Marble is a metamorphic rock composed of carbonate minerals. The terms mafic and felsic do no apply to it.


Does rhyolite have a more mafic composition than basalt?

Rhyolite is not a mafic rock, but a felsic rock, high in silicates, and similar to granite in composition.


Between mafic lava and felsic lava which flowsfaster?

Mafic lava is hotter than felsic lava and therefore flows faster.


What is the comaprison of felsic and mafic?

Felsic minerals are Silicon-rich; whereas Mafic ones are low in Silicon, but contain Iron and Magnesium.


Is quartz monzonite mafic or felsic?

Quartz monzonite ranges from intermediate to felsic.


Is olivine mafic or felsic?

Olivine is a mafic mineral. It is most abundant in ultramafic rocks.


Does the mantle have mafic or felsic in it?

The mantle is ultramafic.


What are the 2 kinds of rock?

Mafic and felsic.