A secret Minoan fire technique may explain how Bronze Age artisans on Crete transformed blue-green stone vases into red ones, according to new research that identifies what appears to be a deliberate use of heat to change the look of stone vessels.
The study was led by Killian Regnier of the Catholic University of Louvain in Belgium and published in the Journal of Archaeological Science: Reports. It centers on 25 red stone vases found at Quartier Mu in Malia, a major Minoan site on Crete dating to about 1800 to 1700 BC.
Researchers say the vessels provide the first documented evidence that Minoan craftspeople intentionally heated stone during vase production for visual effect.
How researchers traced the color change
The vases were made of serpentinite, a stone commonly used in Minoan craftsmanship. In its natural state, serpentinite usually has a blue or greenish color. But the vessels from Quartier Mu stood out because they were red, raising a long-running question about how they got that color.
Some researchers had suggested the stone may have been naturally red. Others raised the possibility of added pigment or accidental burning during the destruction of the site. The new study points instead to deliberate heat treatment.
To test the idea, researchers examined the vases with portable X-ray fluorescence and magnetic susceptibility analysis. Both methods are non-invasive, which means the artifacts could be studied without damage. The team also carried out controlled heating experiments on local Cretan serpentinite to see how the stone changed under different conditions.
The results showed no sign of added pigments on the red vessels. Instead, the color came from changes inside the stone itself.
In the experiments, serpentinite turned red only after it was heated above about 700 degrees Celsius (about 1,290 degrees Fahrenheit) under oxidizing conditions, or in the presence of oxygen.
At that temperature, magnetite inside the stone changed into iron oxides with lower magnetic strength. The same pattern appeared in the ancient vases. The red pieces had much lower magnetic values than the blue, unheated ones.
That match gave researchers a way to trace the ancient process through mineral change rather than surface appearance alone.
Secret Minoan fire technique behind the red stone vases
The study also rejects the idea that the red color was caused by the violent destruction of Quartier Mu. Researchers say the archaeological context does not support a large accidental fire hot enough to produce the same effect on these vessels. They also note that some serpentinite vases exposed to burning kept their original blue color.
Other evidence came from the vases themselves. Cut sections of several pieces showed a clear color gradient. The outer surface was deep red, while the inner core faded to light gray.
Researchers say this pattern is consistent with heating from the outside inward. It does not fit the idea that the vessels were carved from naturally red serpentinite.
The 25 red vessels include bowls, lids, handled cups, teapots, a libation table, a bird’s nest vase, a miniature vase and a spout from an unidentified form. All of those types are common in the Protopalatial period, suggesting the color treatment was applied to standard forms rather than unusual experiments.
Minoan discovery could reshape views of ancient stone craft
The finding adds a new dimension to the picture of Minoan craftsmanship. Stone vase production already required advanced carving and polishing skills. This study suggests some artisans also used fire as a controlled tool to alter appearance and create a stronger visual effect.
Researchers say the work offers more than a single case study. It also presents a practical method for identifying ancient heat treatment in stone artifacts. By combining non-invasive analysis with laboratory heating experiments, archaeologists may be able to detect similar practices elsewhere without harming fragile objects.
For now, the red serpentinite vases from Quartier Mu stand as a rare example of technical choice in Bronze Age Crete. The research suggests their color was not an accident of destruction, but the result of a purposeful process.
That points to a level of experimentation and control that had not been clearly documented before in Minoan stone vase production.
