SAMIAN EARTH, in the materia medica, the name of two species of marl used in medicine, viz. 1. The white kind, called by the ancients collyrium samianum, being astringent, and therefore good in diarrhoeas, dysenteries, and hemorrhagies; they also used it externally in inflammations of all kinds. 2. The brownish-white kind, called after samianum, by Dioscorides; this also stands recommended as an astringent.