Bluestone and sarsen at Durrington

The Durrington MOD site "bluestone lithic" -- possibly rhyolite or ash?  The fresh rock is exposed where a geological slice was taken off for lab analysis.  It's certainly not spotted dolerite......

Thanks to Tony for drawing attention to this -- a short report on what was found during investigations at the old MOD HQ at Durrington prior to development as a housing estate.  The site is about 1 km north of the Durrington Walls scheduled monument

https://www.wessexarch.co.uk/our-work/mod-durrington

There is also a longer published report:

Along Prehistoric Lines: Neolithic, Iron Age and Romano-British Activity in the Former MOD Headquarters, Durrington, Wiltshire
By Steve Thompson and Andrew B. Powell
Published by Wessex Archaeology, 2018

Among the probable Neolithic finds, ..........."the most impressive, at least in size where the pieces of worked sarsen stone blocks found in the posthole alignment, the largest weighing in at 15 kg, with two smaller fragments, interpreted as broken flakes, being found alongside it. The use of sarsen as a material to construct stone circles such as Stonehenge and Avebury may suggest this material had some importance to the occupants of Neolithic Durrington, however it is suggested that the stone was discarded after being unable to be worked further. It is also broadly contemporary with the sarsen phase of Stonehenge, however it is possible sarsen was more commonplace than it is today as a number of solitary standing stones are known locally."

Then we find this, also in a Neolithic context;

A piece of worked ‘bluestone’ known as a biface was found in a later ditch close to the intersection of the two posthole alignments. This object is similar to ones found at Stonehenge and is almost certainly of Neolithic date. However, whilst it is likely to have been brought to the site at this time, it could equally be a Romano-British curio or trophy. ‘Bluestone’ is a key material of non-local rocks, many of which were brought from Wales, and most famous for its use at Stonehenge and the ritual activity taking place there.

This is interesting, in spite of the all too typical assumption that the bluestones found in the area must have been "brought from Wales".......

The lump of bluestone doesn't look much like a typical "biface artifact" to me, but there is a great 3D animation on the Wessex Archaeology web site:

https://sketchfab.com/3d-models/durrington-bluestone-object-3457e4b573914410a63e05d0df7b1f30

This is the description:

The ‘bluestone’ object is a bifacial lithic with polishing and flaking. It was found in a possibly Romano-British feature, next to two Late Neolithic posthole alignments at MOD Durrington. It resembles objects made out of ‘bluestone’, the same as some of the Stonehenge stones. A number of ‘bluestone’ objects have been found across the Stonehenge Landscape, even though not local to the geology.

It is unknown when the object was created, or how it came to be buried at Durrington. Its proximity to the Neolithic posthole alignments could suggest a similar prehistoric date. However, the association with the Romano-British feature could suggest a later curation of the artefact, taken as a memento or trophy.

A section was taken to identify the geology of the rock and shows its original midnight blue colour when it was freshly made. The exterior surface is the result of 4500 years of weathering and wear.

This is all quite intriguing.  No doubt the petrology of the stone will have been sorted out by now.  My best guess is that it is a rhyolite or ash.   The "lithic" is very small, and it does not matter very much whether it is from a Neolithic context or a Romano-British one.  I'll hazard a guess that it is a small erratic pebble that has been bashed about a bit -- but I am unconvinced that the "flaking and polishing" are the results of human interference.  They could be natural features -- and its interesting that the weathered crust (assumed to be the result of just 4500 years of exposure) extends across the whole face of the pebble.  One would have expected the Neolithic (?) flaked areas to show up as a different colour -- with a less well marked crust.   It's difficult to tell what is going on here, even on that wonderful animated 3D image!

Anyway, somebody will probably enlighten us.........

PS.  I knew I wouldn't have to wait for long!  Rob Ixer kindly informs us that it is a piece of foliated rhyolite similar to that found at Rhosyfelin in North Pembrokeshire.  So it can be grouped together with assorted other fragments of the same rock type found  in the Stonehenge landscape.  But this is the first one I've seen that looks like a pebble rather than a fragment knocked off a larger stone.