Last Updated: Nov 22, 2016     Views: 24

From Dr. Robert Brill, Research Scientist Emeritus:

My guess is that it would be either the pigment lead-antimonate (sometimes known when used in Western paintings as "Naples yellow") or a similar compound, lead-tin oxide.  The chemical formulas are:  Pb2Sb2O7 and PbSnO3.  Those were the two most common yellow colorant opacifiers used for some 3300–3400 years of glass history.