chalcedony
/kalˈsɛdəni
/noun (plural chalcedonies) [mass noun]
A microcrystalline type of quartz occurring in several different forms including onyx and agate.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.
Derivatives
chalcedonic
- 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.
Origin
Late Middle English: from Latin calcedonius, chalcedonius (often believed to mean 'stone of Chalcedon', but this is doubtful), from Greek khalkēdōn.