How Raman Spectroscopy Can Be Used to Study Stonehenge

One of the most visually dramatic of the techniques used at Stonehenge is Raman spectroscopy, which is a technique that literally brought a laser to one of the world's most famous prehistoric monuments. In the second episode of “Spectroscopy Around the Globe,” we explored the role that Raman spectroscopy has played in studying Stonehenge.¹

Raman spectroscopy works on the principle of inelastic light scattering. When a laser beam strikes a material, most of the light reflects back at the same wavelength, but a small fraction scatters at a different wavelength, shifted by an amount that corresponds to the vibrational modes of chemical bonds within the material.² This shift acts as a molecular fingerprint, allowing researchers to identify minerals and chemical compounds with great specificity.²

For Stonehenge, Raman spectroscopy has been especially valuable in studying the Altar Stone. Because the Altar Stone is enormous, it cannot be taken to a laboratory. Traditionally, this would have meant taking a small sample to a Raman microscope. Instead, researchers are bringing portable Raman analyzers directly to Stonehenge, conducting their analysis on-site during the night to avoid tourist interference.³

The portable Raman system allows researchers to acquire spectra from different areas of the Altar Stone's surface, building up a mineralogical fingerprint.³ Raman spectroscopy has proved useful for identifying specific minerals and for characterizing iron oxides and titanium oxides that are difficult to distinguish by other field methods.³

Laboratory-based Raman analysis on small fragments of the stone provided complementary high-resolution data, leading researchers to hypothesize that the stone had not originated from the Anglo-Welsh Basin, as had long been assumed.

You can watch the full episode of “Spectroscopy Around the Globe” here: https://www.spectroscopyonline.com/view/spectroscopy-around-the-globe-episode-2-stonehenge.

References

1. Wetzel, W. Spectroscopy Around the Globe, Episode 2 – Stonehenge. Spectroscopy Online, 2026. https://www.spectroscopyonline.com/view/spectroscopy-around-the-globe-episode-2-stonehenge (accessed August 14, 2026).
2. Horiba, What is Raman Spectroscopy? Horiba, 2026. https://www.horiba.com/usa/scientific/technologies/raman-imaging-and-spectroscopy/raman-spectroscopy/ (accessed August 14, 2026).
3. Renishaw, Investigating the secrets of Stonehenge with Raman spectroscopy. Renishaw, 2023. https://www.renishaw.com/en/investigating-the-secrets-of-stonehenge-with-raman-spectroscopy--48452 (accessed August 14, 2026).