A translucent, quartz stone with usually a waxy luster. Chalcedony has tiny microscopic crystals that are sometimes arranged in slender fibrous bands. Agates are a banded variety of chalcedony. A glassy red chalcedony is known as carnelian or sard. A dull green variety colored with nickel oxide is called chrysoprase. Plasma is a bright emerald green chalcedony that is called bloodstone when it contains small red spots of jasper. Chalcedony has been mined or gathered since Paleolithic times. It was used as beads, amulets and seals and is still used as an ornamental stone and gemstone.
Synonyms and Related Terms
carnelian; sard; agate; chrysoprase; citrine; onyx; sardonyx; plasma; bloodstone; jasper; flint; plasma; Chalcedon (Deut.); calcedonia (Esp.); chalcédoine (Fr.); calcédoine (Fr.); chalcedon (Pol.); calcedônia (Port.); chalcedoon (Ned.)
No visible crystals. Sometimes weakly fluorescent.
Fracture = conchoidal. Streak = white. Luster = waxy to vitreous
Mineralogy Database: Quartz
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