An illustration of the use of an atypicality index in provenancing Britishstone axes

An atypicality index has been used to compare the chemical compositions of 11 British prehistoric implements (axes and axe-hammers, and a mace) with p reviously suggested and likely sources in South Wales (Group XIII spotted d olerite from the Carnmenyn area, and Group VIII rhyolite from Carnalw). Aty picality indices together with mineralogy indicate that only two out of six supposed Group XIII implements are likely to be Group XIII, and only one o f the five rhyolite implements is likely to originate from Carnalw. These r esults provide statistical support for earlier provenancing of seven of the implements, and provide the first geochemical source information for four implements. The results illustrate the usefulness of the atypicality index in archaeology, and support the idea that Groups XIII and VIII comprise a l arger variety of chemical types than previously thought. Further work is no w needed to determine how prevalent this variety is within these implement groups.