basaltic rocks are darker because they are more dence
granitic rocks are less dence so they are lighter
less dense
Dark igneous rocks usually have higher amounts of heavier elements such as iron. Light-colored igneous rocks tend to be richer in lighter elements like sodium and aluminum.
Light-coloured igneous rocks, such as granite, have a higher silica content and lower iron and magnesium than darker ones, such as basalt. Since iron and magnesium are very dense minerals, this makes darker igneous rocks more dense than lighter ones.
If you are referring to igneous rocks, they are classified as mafic.
Granitic igneous rocks are light colored rocks of a low density. Granitic magma is thick and stiff and contains a lot of silicon and oxygen. Granitic magma can build up a great deal of pressure, which is released during violent volcanic eruptions.
Generally, igneous rocks that are low in silica are dark relative to those that are high in silica. This tendency is largely the result of rocks low in silica having increased iron. Iron minerals tend to adsorb significant amounts of the visible spectrum and hence appear dark. I want to emphasize that this is a general tendency and there are exeptions -- obsidian which is very high in silica is typically a dark to black rock and a special igneous rock call carbonatite is very light in color but has little silica.
Normally, light colored igneous rocks are less dense compared to dark colored igneous rocks. This is because the light colored rocks have a less iron in them.
less dense
Normally, light colored igneous rocks are less dense compared to dark colored igneous rocks. This is because the light colored rocks have a less iron in them.
Dark igneous rocks usually have higher amounts of heavier elements such as iron. Light-colored igneous rocks tend to be richer in lighter elements like sodium and aluminum.
Light-coloured igneous rocks, such as granite, have a higher silica content and lower iron and magnesium than darker ones, such as basalt. Since iron and magnesium are very dense minerals, this makes darker igneous rocks more dense than lighter ones.
Most dark-colored igneous rocks have a high density.
Most dark-colored igneous rocks have a high density.
Basalt and other dark colored igneous rocks are the most with % of 66% and granite and other light to medium colored igneous rocks fill the other half with 44%
igneous
As a first approximation, the colour of igneous rocks gives an estimate of the concentration of iron in it. Very dark igneous rocks commonly a large fraction of minerals with iron as a major constituent. As those minerals are denser than most other silicate minerals occuring in igneous rocks, dark colored igenous rocks are usually denser than the ligher ones.
Dark colored rocks.
If you are referring to igneous rocks, they are classified as mafic.