Igneous Rocks Vocabulary (Page 6 ESRT)
Magma: This material is what gives rise to intrusive Igneous rocks.
Lava: This material is what gives rise to extrusive Igneous rocks.
Extrusive: Another word for forming above ground.
Intrusive: When Igneous rocks form below ground they are said to be this.
Texture: This feature of an Igneous rock gives rise to its color.
Mineral Composition: The size shape and arrangement of mineral grains gives rise to
this identifiable feature in Igneous rocks.
Plutonic: Another name for rocks that form below ground.
Very Coarse: This texture has crystals greater than 10mm and forms very slowly
underground.
Coarse: This texture has crystals between 1 to 10 mm in size and forms slowly
underground.
Volcanic: When a rock forms above ground it is said to be this.
Fine: This texture is the result of rapid cooling above ground.
Glassy: This texture is the result of very rapid cooling above ground (No visible crystals
present).
Vesicular: When gas filled lava cools and solidifies it forms a rock with this type of
texture.
Mafic: Igneous rocks that are high density, dark in color and rich in Iron and Magnesium.
Felsic: Igneous rocks that are low density, light in color and rich in Aluminum and Silicon.