Estimated Above Ground WeightsWhere they are given, the estimated above ground* weights of the stones are taken from Appendix 1 of the English Heritage publication entitled:
RESEARCH REPORT SERIES no. 32-2012
STONEHENGE LASER SCAN:
ARCHAEOLOGICAL ANALYSIS REPORT
ENGLISH HERITAGE PROJECT 6457
by Marcus Abbott and Hugo Anderson-Whymark, with contributions from Dave Aspden, Anna Badcock, Tudur Davies, Mags Felter, Rob Ixer, Mike Parker Pearson and Colin Richards.
The data is derived from a laser scan of the monument carried out in 2012. It assumes that the specific gravity of the Sarsens is 2.4 and that the specific gravity of the Bluestones is 3 (dolerite) and 2.4 (rhyolite/rhyolitic tuff).
This publication is available online as a PDF.
* As a rough guide, between a quarter and a third of each stone is below ground so the given weights are somewhat less than the total weight.
Bluestone Rock Types
Where the bluestone type is given, the information is taken from "Fig 15 - Composition of Bluestones (after Thorpe et al 1991, fig 1)" in Cleal et al (1995) Stonehenge in its Landscape, p28.
It should be noted that there is a disagreement about whether Spotted versus Unspotted Dolerite is a valid distinction, and also that work is ongoing to identify more specifically the Rhyolitic Ignimbrite (tuff) types.
3D Model Viewer
The 3D models of the stones make use of a feature called "WebGL" which is not supported by all browsers and operating systems. If you have problems viewing the 3D models, try Googling for any known problems with WebGL and your particular flavour of operating system and browser.
For instance, in Chrome on OSX versions lower than 10.8 you may need to go to about:flags and enable "Override software rendering list".