Igneous rock (from the Latin word ignis for fire) is one of the three main types of rocks (the others being sedimentary and metamorphic rocks). Igneous rocks form when molten magma inside the Earth, near active plate boundaries or hotspots, rises towards the surface and cools. Mineral crystals and, sometimes, glass solidify from the magma to form a rock.
Purpose
In the following exercises you will become familiar with the compositions and cooling histories of igneous rocks. You will learn how to identify common igneous rocks based on color and texture, determine the mineral make-up of common igneous rocks, and determine the relationships between igneous rock compositions and tectonic setting.
Learning objectives
After doing this lab you will be able to:
Explain how igneous rocks form underground and above ground.
Explain how to determine the cooling history of igneous rocks based on rock texture.
Explain how to determine the composition of igneous rocks based on rock color.
Explain how igneous rocks of the same composition but different cooling histories have different textures but the same distribution of minerals.
Explain the relationship between igneous rock composition and tectonic setting.
Some of these terms and concepts will be new to you. Don’t worry too much about that – you’ll see them again, and in more detail, later in the course. Try to follow along and work on understanding the terms, but don’t dwell on them. As always, I am available if you need help understanding a term or a concept.
Purpose
In the following exercises you will become familiar with the compositions and cooling histories of igneous rocks. You will learn how to identify common igneous rocks based on color and texture, determine the mineral make-up of common igneous rocks, and determine the relationships between igneous rock compositions and tectonic setting.
Learning objectives
After doing this lab you will be able to:
Explain how igneous rocks form underground and above ground.
Explain how to determine the cooling history of igneous rocks based on rock texture.
Explain how to determine the composition of igneous rocks based on rock color.
Explain how igneous rocks of the same composition but different cooling histories have different textures but the same distribution of minerals.
Explain the relationship between igneous rock composition and tectonic setting.
Some of these terms and concepts will be new to you. Don’t worry too much about that – you’ll see them again, and in more detail, later in the course. Try to follow along and work on understanding the terms, but don’t dwell on them. As always, I am available if you need help understanding a term or a concept.
