IGNEOUS ROCK• Volcanoes eject molten rock
• Molten rock=magma
• Flows when hot and becomes a solid when it cools
• Hardened, cooled magma is called igneous rock.
Magma• Temperatures of magmas range from about
650° to 1,200°C, depending on their chemical compositions and pressures exerted on them.
• Earth’s heat to melt rocks comes from interior
• Radioactive decay of elements is main source of heat.
• Magma is less dense than surrounding rock, which forces it upwards
• When magma reaches Earth’s surface and flows from volcanoes, it is called lava.
• Atoms and compounds in the liquid rearrange into new crystals called mineral grains, when magma cools
• Rocks form when mineral grains grow together.
• Rocks from magma below the surface are called intrusive igneous rocks.
Extrusive Igneous Rock
• Extrusive Rock forms when magma cools on Earth’s surface
• Magma exposed to air and water, thus cools quickly.
Volcanic Glass• Pumice, obsidian, and scoria are examples of
• Rocks cooled so quickly few or no mineral grains formed.
• Pumice and scoria, gases become trapped in the gooey molten material as it cools.
• Basaltic igneous rocks are dense, dark-colored rocks.
• Rich in iron and magnesium and poor in silica.
• FE and MG gives them dark color
• Basaltic Lava is fluid and free flowing.
Granitic and Andesitic Rock• Granitic igneous rocks are light-colored
rocks of lower density than basaltic rocks.
• Thick and stiff magma, high in silica, and low in Mg and FE.
• Andesitic igneous rocks have mineral compositions between those of basaltic and granitic rocks
• Igneous rock is formed by __________.
• A. cooling of hot magma
• B. change in pressure
• C. compression of loose materials
• D. pressure from watery fluids
• What is the difference between intrusive and extrusive igneous rock?
Intrusive igneous rocks form from magma below Earth’s surface. Extrusive igneous rocks form from lava flowing at Earth’s surface.
• Which of the following is a volcanic rock that contained trapped gases during its formation?
• A. marble
• B. pumice
• C. sandstone
• D. slate
Igneous Rock Venn Diagram (22)
• Create a Venn Diagram comparing and contrasting Basaltic, Andesitic, and Granitic Rock.
• Draw a picture to illustrate the difference between the different igenous rocks.
• Write a level 1 or 2 question and its answer for EACH of the following ideas:– Igneous Rock– Lava– Instrusive rock– Extrusive rock– Volcanic glass