Many thanks to Tim Darvill for this summary of Stonehenge work over the past few years. reproduced below is the section relating to the stones -- and in particular, to the bluestone research undertaken in connection with various research projects. I'm interested to see that TD's definition of "bluestone" is pretty close to mine: "non-local stone used in the construction and workings of Stonehenge and found at the site itself and in the wider landscape." No mention of orthostats in that definition, which allows for fragments in the debitage / soil horizons to be included as bluestones -- but I would part company over the assumption that all bluestone fragments must have been used in the construction and working of the monument.
There is a long and comprehensive list of references -- recommended reading.
It's interesting that TD is admitting here to the wide variety of rock types (including some which have not been provenanced) turning up in the bluestone cellection -- and yet the obsession of the archaeology establishment with finding "quarries" appears to be undiminished.....
Research activity in the Stonehenge Landscape 2005–2012Timothy Darvill
Stonehenge and Avebury Revised Research Framework
6 July 2012
Stone sourcing projects
Much new research has been carried out into the geological origins and source
outcrops of the various lithologies subsumed within the term ‘Bluestone’ as applied to
the non-local stone used in the construction and workings of Stonehenge and found
at the site itself and in the wider landscape. Stones SH34 and SH35a have been
shown to be spotted dolerites (also known as Preselite) very similar to samples from
Carn Menyn while stones SH38 and SH40 are two different dacitic crystal-vitric-lithic
ash-flow tuffs and SH46 and SH48 are two different rhyolitic crystal-vitric-lithic ash-
flow tuffs (Ixer & Bevins 2011a). The stone type represented by SH48 was later
defined as rhyolite Group E (Rhyolite with visible feldspar phenocrysts) which is also
represented by two pieces of debitage from the 2008 excavations (Ixer & Bevins
2011a: 22). Group D rhyolites (rhyolitic tuffs with late albite-titanite-chlorite
intergrowths) are mainly confined to samples from the Stonehenge Cursus (see
below) and are of unknown source (Ixer & Bevins 2010: 7; 2011a: 21–22). Three
defined types of rhyolite (A-C) which are not represented amongst standing
Bluestones at Stonehenge but have been recognized as debitage from the 2008
excavations within Stonehenge, the Heel Stone area, several Aubrey Holes, the
Stonehenge Avenue, and the Stonehenge Cursus all derive from a series of
outcrops at Craig Rhos-y-Felin near Pont Saeson on the north side of the Preseli
ridge in Pembrokeshire (Ixer & Bevins 2011b; Bevins et al. 2011; Anon. 2011d;
2012a; 2012b). This source area was the focus of archaeological attention in
Summer 2011 when evaluation trenches against the outcrop located a detached
columular bock and associated hammerstones (Parker Pearson et al. 2012).
A review of samples from the Altar Stone confirmed that it was a fine-to-medium
grained calcareous sandstone of the kind found in the Senni Beds of south Wales.
Four other pieces of sandstone from the Stonehenge Cursus, Stonehenge, Aubrey
Hole 1 and Aubrey Hole 5 share a common lithology as low-grade metasediments
and derive from a different source area, possibly from Lower Palaeozoic sandstone
beds (Ixer & Turner 2006).
An examination of finds from the Cursus Field collected in 1947 and from
excavations by the SRP in 2006 and 2008 confirmed that much of the material could
be matched with samples from Stonehenge (identified as Groups A–D: Ixer & Bevins
2011a; 2011b) but that some rhyolites could not be matched amongst existing
samples (Ixer & Bevins 2010; Ixer et al. forthcoming).
Paul Robinson (2007) reported the results of petrological studies of 21 stone items
from the Devizes Museum collections that were thin-sectioned by the Implement
Petrology Committee of the South Western Federation of Mueums and Art Galleries
in the late 1950s. This includes material from barrows in Wilsford, Shrewton, and
Winterbourne Stoke. An examination of spotted dolerite axeheads from southern
England suggests that some may have been made from pieces of Stonehenge rather
than introduced from more distant sources (Williams-Thorpe et al. 2006).
A new study of jadeite axe-heads from Wiltshire has shown that the example said to
have derived from a barrow near Stonehenge and now in the Sailsbury and South
Wiltshire Museum (Accession number SSWM 28/59 (02919)) is of Alpine rock and is
used to define the ‘Durrington type’ with an almond or teardrop shaped outline and a
sharply pointed butt. The original findspot of the piece remains a matter of debate,
but a good case is made for derivation from the Knighton (Figheldean 27) long
barrow (Sheridan et al. 2010: 26 and fig. 7.2). [Contributions to SRF1 Research
Objectives 1, 5, 22]