Moss agate is a translucent to semitranslucent variety of chalcedony, a microcrystalline form of quartz, distinguished by green, brown, or black inclusions that resemble moss, ferns, or miniature landscapes. The patterns are usually created by inclusions of minerals such as hornblende, chlorite, iron oxides, or manganese rather than actual organic material. It forms when silica-rich groundwater deposits quartz in cavities or fractures, gradually incorporating these mineral inclusions. Moss agate is found in countries including India, Brazil, Uruguay, Madagascar, Australia, Russia, and the United States.

In metaphysical traditions, moss agate is associated with nature, growth, renewal, and emotional balance. It is believed to encourage patience, grounding, abundance, and a deeper connection with the natural world. Some people use it as a meditation stone or carry it as a symbol of new beginnings, steady personal development, and resilience. These metaphysical properties are spiritual beliefs and have not been scientifically proven.