Learn about geology. Topics include minerals, Earth science, volcanoes, rocks, and important geological cycles.

Quartz crystals commonly occur in nature.
A crystal is a form of matter in which the atoms, molecules, or ions are arranged in a highly ordered three-dimensional lattice. Crystals are also called crystalline solids because most crystals are solid. However, liquid crystals also exist. The word “crystal” comes from the Greek word krustallos, which means both […]

What Is a Crystal? Definition and Examples

Galungung volcanic eruption
Volcanic lightning is an electrical discharge produced by a volcanic eruption. Because the static electricity is produced in an ash plume rather than a cloud, volcanic lightning is sometimes called a dirty thunderstorm. History The earliest historical record of volcanic lightning came from the ancient Roman, Pliny the Younger. He […]

How Volcanic Lightning Works