Beginning last year, Jan Elsen has been carrying out a detailed analysis of the mortars used at Sagalassos from Hellenistic until early Byzantine times. Different mortar types were sampled during last week. Most of the samples were taken from the Domestic Area rooms XXXIII, XXXIX, and LI (see Domestic Area, August 3-9), excavated this year. Other mortar and plaster samples were taken in the Roman Baths and from a recently excavated mid-Byzantine cistern on Alexander's Hill (see Alexander's Hill, July 6-12). The ultimate goal is to identify the composition of these different mortars and the mineral resources of its component throughout time, therefore the mineralogical and chemical composition of each sample needs to be determined. This will be done by analyses in the laboratory later this year by means of X-ray diffraction, optical microscopy, and electron microscopy. At the same time, the mortars that used in the conservation activities (see reports on Restoration & Conservation) are closely monitored on a yearly basis for possible signs of stress or decay.