Native Copper Inclusions in Indonesian Purple Chalcedony
As a gem material, chalcedony can contain an array of interesting structures and mineral inclusions. This was particularly evident in one example recently examined by the authors. Purchased by author SC from gemstone dealer John Garsow (John E. Garsow Gems & Minerals, Murrieta, California), this vibrant purple chalcedony reportedly from Indonesia contained several small clusters of what appeared to be native copper (see above). This suspicion was confirmed by energy-dispersive X-ray fluorescence (EDXRF) testing. While the origin of the purple color is not clear, it certainly does not appear to be related to copper. In purple areas that were devoid of copper inclusions, no copper was detected by EDXRF. We did detect iron, which may be related to the purple color.
While native copper inclusions have been previously reported in chalcedony (B.M. Laurs and N.D. Renfro, “Chrysocolla chalcedony with native copper inclusions,” Journal of Gemmology, Vol. 36, No. 2, 2018, p. 92), this is the first time the authors have examined purple chalcedony from Indonesia with native copper inclusions.