Assertion: chalcedony's color | /r/HasProperty | changed in addition
Facets:
Source sentences:
text: In addition, the color of some chalcedony has been changed by heating with the typical end product assuming a reddish hue -- e.g., "Some reddish material sold as carnelian is obtained by the heat treatment of greenish, yellowish, or brown chalcedony" (Frondel, 1962, p.207).