chalcedonic
/ˌkælsɪˈdɒnɪk/ or /kælˈsidɒnɪk/Definitions
1. adjective
Relating to Chalcedon, a city in ancient Bithynia, or to the type of quartz found there.
“The crystal’s chalcedonic structure gave it a unique appearance.”
2. noun
A type of quartz crystal with a fibrous or conchoidal structure.
“The geologist carefully examined the chalcedonic crystals in the rock sample.”