igneous

Traces of it are found in practically all igneous and most sedimentary rocks.

Igneous rocks are formed by the cooling of molten rock material.

The close association both in place and age with igneous rocks.

They occur in limestones and shales and are not associated with igneous rocks.

These are characterized by igneous rocks of andesitic nature.

I did not see any eruption of igneous rock on any part of the day's journey.

To the southward, for fifty miles at least, nothing but igneous rocks can be seen.

Occurs also as crystals in some limestones and igneous rocks.

Some occurs as crystals in igneous rocks, and some in vein deposits.

A common cause of the metamorphism of rocks is the intrusion into them of igneous rocks.