igneous rocks. the rock cycle formation all igneous rocks form from the cooling of melted or molten...
TRANSCRIPT
FormationAll igneous rocks form from the cooling of melted or molten rock.
Lava is molten rock that has exited the Earth through a volcano
Lava
Extrusive RocksVolcanic rock is rock that erupted on the surface and cooled quickly. This could take few minutes to a few hours.
Volcanic rocks or extrusive rocks are Fine Grained or have small mineral crystals
Intrusive RocksPlutonic Rock is rock that solidifies within the Earth from magma that cools very slowly. This cooling could take thousands of years.
Plutonic rocks have a large grain size because the crystals have a long time to growPlutonic Rocks -- Coarse Grained
Porphyritic TextureLarge Crystals in a fine-grained Setting. This indicates there were two different cooling rates. One slow and one fast.
Composition• Composition refers to the chemical make-up of
the rock. This is based on the dominant mineral content.
Mafic Rocks
Mafic igneous rocks contain large amounts of iron(Fe) and Magnesium(Mg). They have high percentages of minerals like amphibole, pyroxene, magnetite and olivine. This makes them dark in color.
Felsic
Felsic igneous rocks have high amounts of Aluminum a Silicon. As a result these rocks are light in color.
Common minerals are quartz, Potassium feldspar, and muscovite mica.
ColorVery Light
LightNotVery LightNot Very Dark
DarkVery Dark
Neither Light nor Dark
Ligh
test
Darke
st
Finding The MineralsIdentify the rock.Unless you have other information,
work in the middle of the rock’s box.