When a liquid metal cools and turns into a solid, its atoms come together to form crystals. The structure of these crystals is not perfect. Sometimes an extra layer of atoms squeezes between other ...

More than 4,000 naturally occurring minerals—inorganic solids that have a characteristic chemical composition and specific crystal structure—have been found on Earth. They are formed of simple ...

A crystallo-chemical enigma, it is one of the few rock-forming minerals with unknown crystal structure.