Ancient technical term used in construction technique. According to Vitruvius (2,8,7 and passim), a term for the frames or facings of walls made from cast cement ( opus caementicium ), later used generally for the covering of floors, roofs and walls with stucco, marble, travertine or mosaic. In toreutics crusta also refers to the relief-adorned ‘jacket’, the ‘shell’ surrounding the body of the receptacle proper.
Georges 1, s.v. c., 1775f.
A. Rumpp, s.v. C., KlP 1, 1336
H.-O. Lamprecht, Opus Caementicium Bautechnik…