Do Plutonic Rocks Have Crystals?

Plutonic rocks, which cool slowly underground, have large crystals because the crystals had enough time to grow to a large size.

What rocks have no crystals?

Examples of aphanitic igneous rock include basalt, andesite and rhyolite. 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. Examples include obsidian and pumice.

Which rocks can have crystals?

Igneous — they form from the cooling of magma deep inside the earth. They often have large crystals (you can see them with the naked eye). Metamorphic — they are formed through the change (metamorphosis) of igneous and sedimentary rocks.