“A Purple Barium Copper Silicate Pigment from Early China”, Elisabeth West FitzHugh, Lynda A. Zycherman1992 (tech)⁠:

A purple barium copper silicate, BaCuSi₂O₆, an artificial inorganic pigment, has been identified, sometimes mixed with the known blue barium copper silicate, BaCuSi₄O₁0.

It occurs on painted objects and in octagonal sticks from China attributed to the Han dynasty (208BC–AD 220).

This man-made pigment, for which the name Han purple is proposed, has not been previously characterized.