A rock that consists of materials that cooled too quickly for crystals to form is called what?

A rock that consists of materials that cooled too quickly for crystals to form is called what?

• A. Igneous
• B. Granite
• C. Magma
• D. Glassy

Answer: (D)

When molten rock cools extremely fast, atoms don’t have time to arrange into a crystalline lattice, so the rock becomes a glassy, amorphous solid. This texture lacks mineral grains and often fractures with a conchoidal pattern. Natural glass such as obsidian is a familiar example. In contrast, rocks that cool more slowly form crystals, like granite with visible grains. So the term that describes a rock formed from materials that cooled too quickly for crystals to form is glassy.

When molten rock cools extremely fast, atoms don’t have time to arrange into a crystalline lattice, so the rock becomes a glassy, amorphous solid. This texture lacks mineral grains and often fractures with a conchoidal pattern. Natural glass such as obsidian is a familiar example. In contrast, rocks that cool more slowly form crystals, like granite with visible grains. So the term that describes a rock formed from materials that cooled too quickly for crystals to form is glassy.