Onyx refers to a parallel banded variety of the silicate mineral Chalcedony. Agate and Onyx are both varieties of layered Chalcedony that differ only in the form of the bands. Agate has curved bands and Onyx has parallel bands. Its bands are parallel to one another, as opposed to the more chaotic banding that often occurs in Agate. These swirls and spirals represent change and development. The colors of its bands range from white to almost every other color. Common specimens of onyx contain bands of black and white. Onyx as a describer, has been applied to varieties, Alabaster, Marble, Obsidian and Opal. Onyx is cryptocrystalline, consisting of fine inter growths of the silica minerals Quartz and Morganite.