What's the difference between chalcedony and sardonyx?

Chalcedony

Definition:

• (n.) A cryptocrystalline, translucent variety of quartz, having usually a whitish color, and a luster nearly like wax.

Example Sentences:

• (1) The free silicic oxide is presented by low-temperature crystobalite and quartz, more rarely opal and chalcedony.

Sardonyx

Definition:

• (n.) A variety of onyx consisting of sard and white chalcedony in alternate layers.

Example Sentences: