You observe a dark colored igneous rock with very fine crystals that are only visible under magnification. What can be said about this rock?
A) It cooled slowly in a magma chamber.
B) It cooled quickly in a magma chamber.
C) It cooled slowly on Earth's surface.
D) It cooled quickly on Earth's surface.
E) It was ejected as a fine ash and later cemented together.

Question

Quizplus · Accepted Answer

The very fine crystals in the igneous rock indicate that it cooled quickly, as there was not enough time for large crystals to form. The fact that it is dark colored and has fine crystals suggests it is likely a type of basalt, which typically forms from lava cooling quickly on Earth's surface.

You Observe a Dark Colored Igneous Rock with Very Fine