Nine lumps of raw iron recovered from the seabed off Israel’s Carmel Coast are shedding new light on how metal was traded across the ancient Mediterranean, according to a study led by researchers at the University of Haifa. The roughly 2,600-year-old iron blocks were discovered during an underwater excavation in the Dor Lagoon and have now been analyzed in research published in the peer-reviewed Heritage Science. Unlike most ancient iron finds, the pieces appear to have remained exactly as they emerged from the smelting furnace, with no signs of forging or further processing, TPS-IL reported.
“This is the earliest archaeological evidence known today of the maritime transport of iron blocks in the state in which they emerged from the smelting process, that is, in the raw state in which they were created in the furnace before undergoing a process of forging and processing by blacksmiths,” said Prof. Tzilla Eshel, who led the study.
The Dor Lagoon, a shallow coastal inlet near the modern town of Dor, has long been both an ecological and archaeological hotspot. Located near the ancient city of Dor—a major Canaanite and later Phoenician port between Haifa and Caesarea—the lagoon served as a natural harbor and hub for maritime trade. Excavations have revealed remains from the Bronze Age, Iron Age, and Hellenistic periods, showing it was used for docking ships as well as industrial activities such as metallurgy and fishing.
While metals such as copper and bronze could be melted and cast, iron production in antiquity involved heating ore with charcoal to create a solid, spongy mass of metal and slag, known as iron bloom or “iron efflorescence.” Blacksmiths would normally reheat and hammer the mass to remove impurities and shape it into usable material.
Laboratory analysis of the Dor Lagoon finds suggests this step never occurred before shipment. Microscopic examination of one bloom revealed a porous internal structure filled with slag residues, with no evidence of hammering or compaction. Chemical tests confirmed the composition of the metal and its surrounding slag layer.
A charred fragment of wood trapped in one of the iron blocks was radiocarbon-dated to between the late seventh and early sixth centuries BCE, shortly before the Babylonian conquest of the Holy Land.
“The internal structure of the metal includes many pores and slag residues, with no signs of forging or hammering, indicating that the iron remained in the condition in which it left the smelting furnace,” the researchers said.
The slag layer also played a crucial role in preservation, acting as a natural protective shell that allowed the metal to survive in excellent condition for more than two millennia underwater.
The findings suggest that iron production and processing were not always centralized. Iron may have been produced at distant smelting sites and transported by sea in its raw form to ports or urban centers, where local blacksmiths completed refining and manufacturing.
“This finding provides important evidence of how metallic raw materials moved between production sites and processing workshops in the late Iron Age, a period of conquering and destructive empires in our region,” the researchers added.
