Examining the distribution of Middle Paleolithic Nubian cores relative to chert quality in southern (Nejd, Dhofar) and south-central (Duqm, Al Wusta) Oman

Lithic raw material properties are often invoked to explain the presence, absence, form, or ontogeny of Paleolithic stone tools. Here, we explore whether the frequency of the Middle Paleolithic Nubian core form and core-reduction systems co-varies with toolstone quality in two neighboring regions in Oman: the southern region of Nejd, Dhofar, and the south-central region of Duqm, Al Wusta. Specifically, we predicted that if raw material differences were influencing the distribution of Nubian cores, the chert would be of higher quality in the southern region, where Nubian cores were frequent, and of lower quality in the south-central region, where they were scarce. We tested this prediction by collecting 124 chert samples from 22 outcrops and then quantitatively assessed two geochemical variables that are widely thought to influence knapping: impurity amount and silica content. We also examined the mineralogical composition, and the crystallite size and lattice strain for quartz (crystalline α-SiO₂) of representative chert samples. Our results suggest that the cherts in the two regions are similar, which is not consistent with the hypothesis that lithic raw material quality contributed to Nubian core spatial distribution in Oman. We discuss potential alternative hypotheses to explain Nubian core geographic patterning, and provisionally suggest that the scarcity of Nubian cores in south-central Oman may be due to a concomitant scarcity of toolmakers, given a lack of water availability.