crystal
n. C / Un. a clear, hard mineral that looks like glass and has a regular shape. You often see these in jewelry or used to make high-quality drinking glasses.
n. a solid material whose constituent atoms are arranged in a highly ordered, repeating microscopic structure. Also refers to high-quality, transparent glass containing lead oxide, valued for its clarity and refractive properties.
The salt formed small, white crystals on the table.
She wore a necklace made of purple quartz crystals that caught the morning light.
Geologists examined the jagged crystal formations within the cave to determine the mineral composition and age of the surrounding rock layers.
Countable when referring to individual mineral units; uncountable when referring to the high-quality glass material.