Definition

1. Noun:
   • A type of onyx: A semi-precious gemstone variety of chalcedony (a type of quartz), characterized by straight, parallel bands of sard (a deep reddish-brown variety of chalcedony) and a lighter-colored mineral, typically white or black onyx.

Examples of Usage

• Noun:

Advanced Usage

• "Cameo from sardonyx": Refers to a carved gem where the design, often a portrait in relief, is created by cutting through a white layer to reveal a darker (sard) background.

Variants and Related Words

• Onyx (n): A banded variety of chalcedony, typically with alternating black and white layers. Sardonyx is a specific type of onyx.
• Sard (n): The deep reddish-brown to brownish-red variety of chalcedony that forms the dark bands in sardonyx.
• Agate (n): Another banded form of chalcedony, but with curved or concentric bands, unlike the straight, parallel bands of onyx and sardonyx.

Synonyms

• Banded onyx: A descriptive synonym emphasizing the layered structure.
• Layered chalcedony: A more general geological term.

Related Phrases

• Sardonyx cameo: The most common artistic application of this stone.
• Layer of sard: Refers specifically to the reddish-brown band within the stone.

Noun

1. an onyx characterized by parallel layers of sard and a different colored mineral