SARDONYX, a variety of agate with alternating orange and white bands


  • VARIETY OF: Crypto-crystalline Quartz , SiO2
  • USES: Gemstone and ornamental stone.
  • COLOR: alternating bands of yellow-brown and white
  • CLEAVAGE: none
  • CRYSTAL SYSTEM: none visible (actual crystals are microscopic)
  • For natural Sardonyx mineral specimens see our For Sale or Sold lists

Sardonyx is a banded variety of chalcedony (cryptocrystalline quartz), with layers alternating between Sard and Onyx. It is an impure fine-grained quartz whose crystals are too small to see.

The color is usually a yellow-brown alternating with white, but other variants are also called sardonyx.

The banded nature of sardonyx is used to advantage by lapidaries and artisans, as a careful selection of material and design allows the creation of bas-relief art, where one layer is left as a foreground, and another is used as the background for a carving.

Sardonyx is the traditional birthstone for August. It is associated with relaxation and security.

Sardonyx is only one of several chalcedony (cryptocrystalline quartz) varieties. The primary varieties are as follows:

  • Agate is a banded variety (sometimes with translucent bands)
  • Bloodstone is green with red speckles
  • Carnelian is yellow to orange
  • Chrysoprase is green
  • Flint is generally black with a fibrous microscopic structure
  • Jasper is any colorful agate
  • Onyx is black, white, or alternating black and white
  • Sard is yellow to brown
  • Sardonyx is banded, alternating sard and (usually white) onyx

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