Which of the following is an example of extrusive rock that has cooled too quickly for grains to form?

a. Volcanic glass

b. Basaltic rock

c. Granitic rock

d. All of the above

Volcanic glass because when magma cools quickly, no crystals form. This creates a glass texture, known as a hyaline texture. An extrusive rock is a rock that cools outside of the earth's surface. This allows the magma to cool too quickly for large crystalline structures to develop. The result is a rock with small crystals that resembles glass.