colcotar

colcotar [Ar. qulquṭār] , colcothar, iron peroxide. M. Scot Lumen 260 (v. chalcanthum); si vis aliquid corrodere, adde modicum de ~ar, i. de atramento citrino Gad. 118. 1 (cf. ib. 121v. 1: ~ar adustum, i. auripigmentum citrinum adustum); calcater, i. atramentum citrinum SB 13.