chalcedony

American  

[kal-sed-n-ee, kal-suh-doh-nee] / kælˈsɛd n i, ˈkæl səˌdoʊ ni /

noun

plural

chalcedonies

1. a microcrystalline, translucent variety of quartz, often milky or grayish.

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chalcedony British  

/ kælˈsɛdənɪ, ˌkælsɪˈdɒnɪk /

noun

1. a microcrystalline often greyish form of quartz with crystals arranged in parallel fibres: a gemstone. Formula: SiO 2

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chalcedony Scientific  

/ kăl-sĕd′n-ē /

1. A type of quartz that has a waxy luster and varies from transparent to translucent. It is usually white, pale-blue, gray, brown, or black and is often found as a lining in cavities. Agate, flint, and onyx are forms of chalcedony. Chemical formula: SiO ₂ .

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Other Word Forms

• chalcedonic adjective
• chalcedonous adjective

Etymology

Origin of chalcedony

First recorded in 1275–1325; Middle English calcedonie, from Late Latin chalcēdōnius (Vulgate, Revelation 21:19), equivalent to chalcēdōn- (from Greek chalkēdṓn “chalcedony,” identified by Saint Jerome with Chalcedon, the city) + -ius adjective suffix; see -ious

Example Sentences

Encased in blue chalcedony, set with diamonds and hung from a black silk ribbon, the piece is a contemporary interpretation of Baillères’ Mexican heritage.

From Los Angeles Times • Apr. 9, 2026

One supposed mammal tooth was actually a bit of the mineral chalcedony.

From New York Times • Feb. 21, 2023

Watts gleamed in jewels, pairing her pavé diamond rings with a dazzler of a sapphire, diamond and chalcedony necklace.

From Los Angeles Times • Feb. 19, 2015

The subtle color mixes included lilac diamonds with lavender chalcedony, purple sapphires and pink spinels.

From New York Times • Jul. 4, 2011

The box was carved wood, its mother-of-pearl lid inlaid with jasper and chalcedony.

From "A Clash of Kings" by George R.R. Martin