A new study has uncovered the entire manufacturing process of a unique 3,600-year-old Bronze Age disk.
Photo: Frank Vincentz
German researchers have reconstructed the ancient techniques used to create the Nebra Disk, one of the most famous archaeological finds, revealing the impressive metallurgical skills of Early Bronze Age craftsmen.
About the Nebra Disk
The Nebra Disk was discovered by looters in 1999 at the Mittelberg Hill archaeological site near Nebra, Germany. It is a bronze artifact about 30 centimeters in diameter, decorated with astronomical symbols including the sun, moon, crescent, and stars, all inlaid with gold leaf and dots.
Dating from roughly 1800 to 1600 BCE, the disk is attributed to the Unetice culture of Central Europe.
It is widely regarded as the oldest known representation of the cosmos in the world and is believed to have been used for astronomical observations or rituals.
Uncovering the Manufacturing Techniques
Researchers at Otto von Guericke University Magdeburg, working with the State Office for Heritage Management and Archaeology of Saxony-Anhalt, applied modern forensic and experimental archaeology methods to reveal how the disk was made.
The team, led by Professor Dr. Thorsten Halle from the Institute of Materials, Technologies and Mechanics, employed Scanning Electron Microscopy (SEM) and Electron Backscatter Diffraction (EBSD) — two advanced techniques from materials science and engineering used to study the microstructure and crystal formation of metals — to analyze a microscopic sample from the original disk.
These methods helped the researchers understand the crystal structure of the metal and the heating and processing steps the disk underwent.
The Metallurgical Process
According to Dr. Halle, the disk was first cast at temperatures exceeding 1200°C. It then underwent repeated heating cycles at about 700°C and was hammered approximately ten times. This cycle of heating and reshaping is characteristic of a process known today as recrystallization, where the metal "heals" by forming new grains after deformation, restoring its ductility and workability.
This advanced thermal treatment and forging process reveal a sophisticated empirical understanding of metal behavior, despite the absence of written knowledge, machines, or measuring tools in that era.
Reconstructing Ancient Craftsmanship
The ancient manufacturing secrets of the Nebra Disk are being reconstructed by Dr. Christian-Heinrich Wunderlich from the State Office for Conservation and Archaeology of Saxony-Anhalt (pictured front with a replica of the disk) alongside Professor Dr. Thorsten Halle (pictured behind) at the Otto von Guericke University Magdeburg’s laboratory, where the research took place.
Photo: Jana Dünnhaupt/University of Magdeburg
Dr. Halle explained, “This kind of detailed manufacturing analysis shows striking similarities with modern industrial processes. We carefully study the metal’s history, almost like reading a diary.”
Experiments with Bronze Age Techniques
To test the production process, the research team collaborated with expert coppersmith Herbert Bauer, who created multiple replicas using Bronze Age tools and methods such as stone hammers and charcoal-fired furnaces.
These replicas were examined under the same conditions as the original disk, and their microstructure was compared. The strong similarities confirmed the hypothesized production methods.
Their findings were published in November 2024 in Nature Scientific Reports, sparking global interest.
A Mobile App for Non-Invasive Material Analysis
Beyond shedding light on ancient craftsmanship, the study suggests that Bronze Age artisans possessed a deeper knowledge of materials science than previously thought.
Building on this, researchers at Magdeburg are now developing a mobile phone app based on eddy current technology, which will allow archaeologists to analyze the material history of metal artifacts on-site using just a smartphone — all without causing any damage to the objects.
