Why are igneous rocks called primary rocks?

1 Answer
Nov 5, 2015

As igneous rocks are formed from magma and begin the rock cycle, they are called primary rocks.

Explanation:

Igneous rocks are created from the cooling of molten magma/lava. All other rocks are derived from them, which is why you will also find them referred to as parent rocks on occasion.

This image is a pretty good illustration of the rock cycle:

http://www.cotf.edu/ete/modules/msese/earthsysflr/rock.html

As you can see, it starts with magma #-># igneous rock. From there, all other manner of rocks can be made.