1. Banded or cloudy quartz with a waxy appearance: An agate is a semiprecious stone revealing different tints or colors, and are displayed quite artistically.
2. Cryptocrystalline with crystals that are too small to be seen with an optical microscope: An agate contains silica that is composed of cloudy and banded chalcedony (translucent or grayish semiprecious stone), sometimes mixed with opal, which forms in rock cavities.