cobalt oxide

Ingredients

cobalt oxide, iron, copper, zinc

Preparation Steps

Original Recipe Text

The pigment consists of cobalt oxide integrated into a glass melt. LA-ICP-MS analysis revealed the presence of indium (typically 1-2 ppm) associated with these cobalt-colored glasses. The ratios of cobalt to indium vary from several hundred to one to greater than 1,000 to one (p. 129).

Evidence

"Eight glasses are colored by cobalt oxide, at least in part. They range from a greenish blue to dark blue. All of the cobalt-containing glasses were found to have relatively high concentrations of iron, compared with the colorless glasses, and they also have small amounts of copper and zinc."

Remarks

The cobalt-blue glass from the cameo fragment (MMA 40.170.181) is noted for having a high content of zinc oxide, nearly three times that of the cobalt, which distinguishes it from other blue samples found at the site (p. 129).