Micro-World Gems & Gemology, Winter 2022, Vol. 58, No. 4

Copper “Confetti” Inclusions in Chalcedony

Nathan Renfro

Download PDF
Figure 1. This new chalcedony from Indonesia, which one dealer is marketing under the trade name “Aquadite,” contains numerous inclusions composed of copper and copper minerals such as red cuprite, blue chrysocolla, and green malachite. The largest triangular cabochon weighs 78.80 ct. Photo by Annie Haynes; courtesy of Yianni Melas.
 
Figure 1. This new chalcedony from Indonesia, which one dealer is marketing under the trade name “Aquadite,” contains numerous inclusions composed of copper and copper minerals such as red cuprite, blue chrysocolla, and green malachite. The largest triangular cabochon weighs 78.80 ct. Photo by Annie Haynes; courtesy of Yianni Melas.

Recently the author examined an interesting new variety of chalcedony from Indonesia (figure 1). Samples were sourced from Greek dealer Yianni Melas in order to document the new material. Gemologically, the properties are consistent with chalcedony, including a refractive index of 1.54 and a specific gravity of 2.56. However, this material is particularly notable for its mineral inclusions. Much like confetti thrown in the air as a celebration, a multitude of blue, green, and metallic inclusions (figure 2) were scattered throughout the chalcedony matrix. Advanced testing, including Raman spectroscopy and energy-dispersive X-ray fluorescence analysis combined with microscopic observation, confirmed the presence of chrysocolla, malachite, native copper, and cuprite.

Figure 2. The Indonesian chalcedony contains vibrant inclusions such as greenish blue chrysocolla (A), green malachite, and well-formed crystals of native copper that has in some cases altered to the deep red mineral cuprite (A, B, and C). Photomicrographs by Nathan Renfro; fields of view 10.27 mm (A), 4.17 mm (B), and 4.77 mm (C).
 
Figure 2. The Indonesian chalcedony contains vibrant inclusions such as greenish blue chrysocolla (A), green malachite, and well-formed crystals of native copper that has in some cases altered to the deep red mineral cuprite (A, B, and C). Photomicrographs by Nathan Renfro; fields of view 10.27 mm (A), 4.17 mm (B), and 4.77 mm (C).

Melas plans to market this new material under the trade name “Aquadite.” This fascinating chalcedony from Indonesia should be a popular gem for any collector who enjoys unique examples of vibrantly colored chalcedony.

Nathan Renfro is senior manager of colored stone identification at GIA in Carlsbad, California.