Quarried since the Tang dynasty from Duanxi (
端溪) in Zhaoqing (
肇庆), Guangdong. Prized for its fine-grained stone that grinds ink smoothly without wearing the brush. Collectors look for 'eyes' (
石眼, natural mineral inclusions) — particularly
活眼 (live eyes) with concentric rings — as marks of quality and rarity.