Black (arrowed) romarchite crust over bronze (~75% Cu, ~6% Sn, ~15% Pb, ~4% As) Chong Ning Tong Bao (1102-1106 A.D.) 5 cash coin (d 33 mm) of emperor Hui Zong of Northern Song dinasty. Thin (~150 mkm) black romarchite-cerussite film is overgrown by copper one (up to 1 mm) composed by malachite and former azurite. Coin was found in Khabarovskiy Kray in 2004. Pavel M. Kartashov collection #3456 & photo.
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