A silicone-based mineral closely related to quartz and agate, Chalcedony has a unique crystalline structure that gives it an enormously variable appearance. This mineral forms in a similar fashion to agates and geodes but due to heat and pressure at the time of formation results in a distinct look and almost silky texture. Chalcedony can be found in a range of colors but most often occurs in semitransparent or white. It has a long archaeological record of human use as a cutting or carving tool, dating back as far as 32,000 BC. Chalcedony has a number of forms that are also considered gems of their own, such as agates, carnelian, and onyx. These unique, highly variable Chalcedony spheres or roses are almost geode-like in appearance and one can clearly see the process of geode or agate formation in progress in each specimen.