NMR in Archaeology: Exploring Its Use Beyond Medicine

Historically, NMR was a tool for liquids. Archaeologists would have to dissolve a sample to analyze it, which often meant destroying the very artifact they were trying to save. However, the development of High-Resolution Solid-State NMR, specifically using Magic Angle Spinning (MAS), changed the game [1].

Researchers can now analyze bulk organic materials like bone, wood, and textiles in their solid form. Recent advancements have even reduced the required sample size to less than 5 mg, making the technique virtually non-destructive for larger artifacts [1].

One of the most profound applications of NMR is identifying “invisible” history—the organic residues trapped in the pores of ancient pottery.

1. Diet and Food Processing

Studies on Roman-era vessels found in the Netherlands used Carbon-13 CP/MAS NMR to analyze charred food remains. By comparing these to modern references, scientists identified specific lipids and proteins that indicated what these ancient populations were cooking [4]. This goes beyond mere “meat or plant” identification; NMR can distinguish between different types of resins, fats, and oils used as ancient adhesives or sealants.

2. The Mystery of Waterlogged Leather

Archaeological leather is notoriously difficult to conserve. In a landmark study published by Analytical Chemistry, NMR was used to analyze shoe soles from the 13th to 17th centuries found in Lyon, France [2].

• The Findings: The NMR spectra revealed an almost total absence of tannins and lubricants, likely leached out by centuries in a water-rich environment.

• The Paradox: Despite the lack of preservatives, the collagen was surprisingly well-preserved. NMR and Electron Paramagnetic Resonance (EPR) showed that the accumulation of iron oxides from the surrounding sediment likely played a role in stabilizing the leather’s molecular structure [2].

NMR is the gold standard for provenancing amber (fossilized resin). Because the chemical “fingerprint” of resin changes based on the tree species and geographical location, Solid-State NMR can determine if a piece of amber found in a Viking grave originated in the Baltic region or the Dominican Republic [1]. This data allows archaeologists to map prehistoric trade routes with incredible precision.

For massive finds like the Mary Rose or ancient dugout canoes, knowing the internal state of the wood is critical for survival. NMR Relaxometry and Cryoporometry are used to measure pore size distribution within waterlogged wood [3].

• When wood degrades, the cellulose and lignin break down, increasing the volume of “large pores.”

• NMR measures how water molecules move within these pores.

• This allows conservators to determine exactly how much polyethylene glycol (PEG) or other consolidants are needed to prevent the wood from collapsing as it dries [3].

Perhaps the most exciting development is Unilateral (Single-Sided) NMR. Traditional NMR requires putting the sample inside a giant magnet. Unilateral NMR uses a portable, open magnet that can be placed against a wall or a large statue [4].

• Fresco Analysis: It has been used to scan 16th-century wall paintings to detect moisture layers and salt crystallization behind the paint before it flakes off.

• Mummy Scans: Portable NMR has even been used for non-invasive spatial tissue discrimination in ancient mummies without removing them from their sarcophagi [4].

Main Points Covered

• Solid-State NMR has revolutionized archaeology by allowing the analysis of solid artifacts (bone, leather, wood) with minimal sample destruction.
• Molecular Fingerprinting enables the identification of ancient diets and the origin of materials like amber, helping map ancient trade routes.
• Conservation Science relies on NMR to assess the decay of waterlogged artifacts, ensuring they don’t disintegrate during the drying process.
• Portable NMR sensors now allow for the non-invasive “scanning” of immovable monuments, frescoes, and even mummies.

Action Plan for Researchers & Scholars

1. Identify Material Type: Use Solid-State CP/MAS NMR for organic solids (textiles, bone) and Liquid-State NMR for extracted residues (pottery oils).
2. Assess Sample Stability: For waterlogged finds, utilize NMR Relaxometry to determine the degree of cellulose degradation before beginning conservation.
3. Non-Invasive Monitoring: For immovable heritage (statues/murals), employ Unilateral NMR to monitor internal salt and moisture levels.

Final Thought

While NMR’s contribution to medicine is vital, its role in archaeology provides something equally essential: a clearer, data-driven window into our collective past. It proves that even the smallest molecular signal can tell a story that has been silent for thousands of years.