Onyx is a type of chalcedony, which is a silicate mineral and a form of microcrystalline quartz. It is primarily known for its parallel banded structure, with straight, nearly parallel bands or layers of color. The colors of onyx bands can range from black to almost every color, with common specimens containing black and/or white bands. Onyx is often used in jewelry making, particularly black onyx, which is a popular gemstone.
The name "onyx" comes from the Ancient Greek word ὄνυξ, meaning "claw" or "fingernail," as onyx with flesh-colored and white bands can resemble a fingernail. Onyx has also been applied as a descriptive term to parallel banded varieties of alabaster, marble, calcite, obsidian, and opal, as well as materials with contorted banding, such as "Cave Onyx" and "Mexican Onyx".
In addition to its use in jewelry, onyx has been used for various purposes throughout history. It has been used for fireplace surrounds, household furniture, and ornaments. In ancient times, onyx was believed to bring courage and protect warriors from harm. Today, it is carried or worn for protection against dark forces and to promote a sense of security. Onyx is also believed to help with the release of negative emotions and past traumas, promote self-control and discipline, and ease addictive patterns of behavior and destructive habits.
