
A renowned mosaic of Alexander the Great, discovered in Pompeii, contains approximately 2 million tiny stones sourced from regions far beyond his ancient empire, according to a new analysis of Alexander the Great’s mosaic.
While Alexander’s empire extended from Greece to present-day Pakistan, researchers found that the materials for this intricate artwork came from various parts of Europe and North Africa. Stones, or tesserae, were identified from quarries in Italy, Spain, and Tunisia, showing a wide-ranging supply network used during Roman times.
The mosaic, estimated to be 2,000 years old, was buried under volcanic ash when Mount Vesuvius erupted in 79 A.D., obliterating the city of Pompeii. It was unearthed in 1831 within a wealthy home known as the House of the Faun. Today, it is preserved at the National Archaeological Museum in Naples.
Alexander the Great’s mosaic analysis
Researchers describe the Alexander Mosaic as “the most important mosaic of the Roman age.” It depicts Alexander leading his army to victory against Persian King Darius III, capturing a scene from the Battle of Issus in 333 B.C., near what is now the Turkish-Syrian border. A single tree in the background, which some medieval texts referred to as the “solitary tree,” further identifies the location.
In 2020, the Naples museum launched a detailed restoration of the mosaic. The project used advanced but noninvasive tools to analyze its composition, including portable X-ray fluorescence. This technology allowed researchers to identify the elements within the tesserae.

The study found that the mosaic used ten distinct colors, ranging from white, red, and yellow to pink, blue, and green. These colors were masterfully combined to create lifelike effects.
Notably, Alexander’s face received special attention, with artisans using various shades of pink to highlight features and achieve light and shadow effects. Researchers noted that this craftsmanship made the mosaic one of the most iconic images of Alexander in ancient art.
Origins of the stones on the mosaic
The origins of the stones were also investigated. Some white stones may have come from quarries in the Apuan Alps of Italy, known for their fine white limestone. Vibrant pink stones likely came from Portugal, while yellow tesserae were traced to the ancient Roman city of Simitthus, now in Tunisia. Dark red stones might have been sourced from Cape Matapan in Greece.
The study also uncovered traces of natural wax and gypsum, materials likely applied during modern restoration efforts. An endoscopic examination of the mosaic’s backside revealed gaps where gypsum may have been inconsistently applied, possibly during its transfer from Pompeii to the museum. Researchers recommended addressing these weak points in future restoration projects to preserve the artwork.
The findings, published in the journal PLOS One on Jan. 15, shed new light on the mosaic’s construction and the global connections of ancient artisans.