calcedony vs chalcedony

calcedony and chalcedony both are nouns.

Word	Noun	Adjective	Verb	Adverb
calcedony	Yes	No	No	No
chalcedony	Yes	No	No	No

As nouns, calcedony and chalcedony are synonyms defined as:

calcedony and chalcedony: a milky or greyish translucent to transparent quartz

calcedony (noun)	chalcedony (noun)
a milky or greyish translucent to transparent quartz	a milky or greyish translucent to transparent quartz