Blue onyx is a banded variety of chalcedony, a microcrystalline form of quartz, characterized by layers in shades of pale blue, deep blue, white, gray, or occasionally brown. Much commercial “blue onyx” is actually banded calcite or aragonite rather than true quartz onyx, and some material may be dyed to enhance its color. It forms when mineral-rich groundwater deposits successive layers inside cavities, veins, or fractures in rock. Blue onyx and similar blue-banded stone are commercially sourced from countries including Pakistan, Iran, Turkey, Mexico, Brazil, Argentina, and the United States.

In metaphysical traditions, blue onyx is associated with calmness, communication, emotional balance, and mental clarity. It is often believed to encourage peaceful self-expression, patience, and resilience during periods of stress or change. Some practitioners connect its blue color with the throat chakra and use it in meditation or as a symbolic aid for speaking honestly and thoughtfully. These metaphysical properties are spiritual beliefs and have not been scientifically proven.