Definition of chalcedony in English:

Share this entry


Pronunciation: /kalˈsednē/
Pronunciation: /CHalˈsednē/ Pronunciation: /ˈkalsəˌdōnē/ Pronunciation: /ˈCHalsəˌdōnē/

noun (plural chalcedonies)

A microcrystalline type of quartz occurring in several different forms, including onyx, agate, and jasper.
Example sentences
  • Common cements include clay minerals such as kaolinite, montmorillonite, or illite; quartz or chalcedony; iron oxides such as haematite; or calcite.
  • Vein minerals are barite, calcite, chalcedony, and quartz.
  • The shoots and stalks themselves are casts composed of combinations of chalcedony, quartz, calcite, and barite.



Pronunciation: /ˌkalsəˈdänik/
Example sentences
  • The Main vein is 7-8 feet thick, extends for 300 feet along strike, and consists of chalcedonic quartz.
  • There is no chalcedonic quartz anywhere within or on the specimen.
  • The formation is composed largely of dark limestone and dolomite, and contains black chalcedonic chert in fine laminated layers, a piece of which is displayed near the bottom of this page.


Late Middle English: from Latin calcedonius, chalcedonius (often believed to mean 'stone of Chalcedon', but this is doubtful), from Greek khalkēdōn.

For editors and proofreaders

Syllabification: chal·ced·o·ny

Share this entry

What do you find interesting about this word or phrase?

Comments that don't adhere to our Community Guidelines may be moderated or removed.