Igneous Rocks
Igneous rock definition Rocks formed by the cooling and solidifying of molten materials. Igneous rocks can form beneath the Earth’s surface from magma, these are intrusive igneous rocks Or on the earths surface from lava, these are extrusive igneous rocks
Igneous Rock characteristics Texture: Very Course, Course, Fine, Glassy, Vesicular and non-vesicular Color: Light or Dark Density: High or Low Composition: Felsic Al, Si or Mafic Fe, Mg If a Rock is Dark in color it will also have a Mafic composition and a High density. If a rock is Light in color it will also have a felsic compostion and a Low density
Very Course to Course Texture Crystal size 1mm to 10mm Very Course Crystal size 10mm or larger
Fine Texture Fine Crystal size Less then 1 mm
Meaning no visible crystals Glassy Texture Crystal size Non-crystalline Meaning no visible crystals
Vesicular Texture Visible gas pockets
Mafic Intrusive rock Gabbro Large crystals Dark in color
Mafic extrusive rock Basalt small crystals Dark in color
Felsic Intrusive rock Granite Large crystals Light in color
Felsic extrusive rock Rhyolite Small crystals Light in color