Treasures in the Attic: Testing Cunnington’s assertion that Stone 32c is the ‘type’ sample for Andesite Group A

In 1881 Willian Cunnington excavated and sampled buried Stone 32c from within the Stonehenge Circle and described it as a ‘calcareous chloritic tuff’. He suggested that it was the source (type material) for similar looking debitage within the Stonehenge Landscape. Last described fifty years ago his original thin sections have been rediscovered and their investigation has shown that it was a reasonable conclusion based on his limited sampling. However, twenty first century investigations of thousands of pieces of this debitage, now defined as Andesite Group A (formerly Volcanic Group A), show it to possibly comprise two sub-groups, one being calcite-rich and the other being calcite-poor. Thin sections from Stone 32c show many of the characteristics of the calcite-bearing sub-group, but fewer of the calcite-poor sub-group but, for the present, Stone 32c is assigned as the type material for all Andesite Group A. However, Stone 32c may be the sole parent to all Andesite Group A debitage or only its calcite-bearing sub-group or it may share parentage for some or all of Andesite Group A with at least four other, as yet unsampled, stones (33e, 33f, 40c and 41d) buried within the Stonehenge Circle. Further research will answer these questions.