What condition results in magma cooling and forming a "glassy" igneous rock?

A)

extremely slow cooling

B)

cooling in the presence of oxygen

C)

extremely rapid cooling

D)

partial melt cooling

E)

extremely high pressure

C

Explanation:

Glassy or vitreous textures occur during some volcanic eruptions when the lava is quenched so rapidly that crystallization cannot occur. The result is a natural amorphous glass with few or no crystals. As magma cools slowly the minerals have time to grow and form large crystals.

Your correct answer is C) extremely rapid cooling