Igneous Rock Classification Vocabulary
Establish understanding of Igneous Rocks
Igneous Rock – Rock formed by the cooling and hardening of molten magma
Magma – Hot fluid withing the Earth's Core
Lava – Magma when it reaches the Earth's surface
How Igneous Rocks are classified
Color – The color of the rock
Light = White, Pink, Light Blue, Light Gray, Purple
Intermediate = 50/50 Light and Dark
Dark = Black, Dark Gray, Brown
Ultramafic = Green
Texture – Grain Size = How large the grains are in the rock
Glassy = No visible grains ) Caused by slow cooling rate
Fine = Small grains (< 1mm) ) (Intrusive)
Coarse = Moderately-sized grains (1mm- 10 mm) ) Caused by rapid cooling rate
Very Coarse = Large grains (>10mm) ) (Extrusive)
Formation – Where the rock forms at
Intrusive = Occurs under the earth's surface, results in large grains
Extrusive = Occurs on the earth's surface, results in small grains
Porphyritic – Has different types of grains mixed in with the grains (background)
Yes = Has different sized grains mixed in with the solid base (matrix)
No = Does not have different sized grains mixed into it
Igneous Rock – Rock formed by the cooling and hardening of molten magma
Magma – Hot fluid withing the Earth's Core
Lava – Magma when it reaches the Earth's surface
How Igneous Rocks are classified
Color – The color of the rock
Light = White, Pink, Light Blue, Light Gray, Purple
Intermediate = 50/50 Light and Dark
Dark = Black, Dark Gray, Brown
Ultramafic = Green
Texture – Grain Size = How large the grains are in the rock
Glassy = No visible grains ) Caused by slow cooling rate
Fine = Small grains (< 1mm) ) (Intrusive)
Coarse = Moderately-sized grains (1mm- 10 mm) ) Caused by rapid cooling rate
Very Coarse = Large grains (>10mm) ) (Extrusive)
Formation – Where the rock forms at
Intrusive = Occurs under the earth's surface, results in large grains
Extrusive = Occurs on the earth's surface, results in small grains
Porphyritic – Has different types of grains mixed in with the grains (background)
Yes = Has different sized grains mixed in with the solid base (matrix)
No = Does not have different sized grains mixed into it