chalcedony


chalcedony

Very fine-grained variety of the silica mineral quartz. A form of chert, it occurs in a great variety of colours, usually bluish white, gray, yellow, or brown. Other physical properties are those of quartz. For centuries, chalcedony has been the stone most used by gem engravers, and many varieties are still cut and polished as ornamental stones. See also agate; carnelian; onyx.

Variants of CHALCEDONY

chalcedony or calcedony

This entry comes from Encyclopædia Britannica Concise.
For the full entry on chalcedony, visit Britannica.com.

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