Archaeologists have found a large Iron Age industrial complex on Israel’s Carmel Coast that produced the luxurious purple dye once exclusively reserved for royalty and high priests. The discovery, made at Tel Shiqmona near modern Haifa, is of an ancient production site operating on a commercial scale between 1100 and 600 BCE. This period is consistent with the biblical Kingdom of Israel and the era of the First Temple in Jerusalem.

Stone tools with purple dye residue. Credit: Maria Bukin; G. Shalvi et al., PLOS ONE (2025)

Published in PLOS ONE, the research was led by Dr. Golan Shalvi from the Zinman Insтιтute of Archaeology at Tel Aviv University and the University of Chicago, and Professor Ayelet Gilboa. The excavation team comprised experts from different insтιтutions in the United States and Israel.

Tel Shiqmona is currently recognized as the only site in the Near East—and possibly throughout the Mediterranean—where a continuous record of purple-dye workshops has been revealed. The find presents unparalleled evidence of the tools, scale, and methods used in the production and extraction of Tyrian purple, a precious and expensive dye derived from the mucus of marine mollusks.

Hexaplex trunculus shell collected near Tel Shiqmona. 400 such shells were identified by two free-style divers within 90 mins at a depth of one to two meters on October 20, 2020. PH๏τo by Ayelet Gilboa. Credit: G. Shalvi et al., PLOS ONE (2025)

Among the most significant discoveries were huge ceramic vats, some of which were stained a deep purple. One meter high and 80 centimeters in width at their openings, the vats each held about 350 liters. Up to 15–20 of these vats would have been in use simultaneously, scientists estimate, during peak periods, emphasizing the industrial scale of the site.

Body sherds of purple dye vats with purple dye remains. Credit: Credit: G. Shalvi et al., PLOS ONE (2025)

There were a total of 176 production-related artifacts for dye discovered—135 of them stained with purple pigment. They include grinding stones, mollusk shells, and other processing tools. The consistent form and spatial organization suggest a very efficient system of production that existed for nearly 500 years.

According to Prof. Zohar Amar of Bar-Ilan University and co-author of the study, purple dye—the argaman in Hebrew—was produced by exposing the greenish mucus from sea snails to air, which caused a chemical reaction that changed it into the famous purple color. The pigment was chemically bonded to the textiles in a multi-step process. While Tel Shiqmona’s humid climate has likely destroyed any remaining fabric, the presence of purple-dyed material in the dry Timna Valley suggests that Tel Shiqmona may have been the source of that dye.

Profile views, section drawings, and bottom views of bases of purple dye vats (PH๏τos by Maria Bukin; drawings by Vladimir Lehem). Credit: Credit: G. Shalvi et al., PLOS ONE (2025)

The significance of this dye in culture is noted in biblical references. Purple and blue yarns are part of the sacred materials used for constructing the Tabernacle, as per the Book of Exodus (25:2–7). This dye is also mentioned in the ᴀssyrian King Sennacherib’s inscription, dating back to around 690 BCE.

Although earlier archaeological excavations at Tel Shiqmona were carried out as early as the 1960s, most of the material from that period remained unpublished. Dr. Shalvi and his team went back to the location to illuminate its stratigraphy and reanalyze older material before finally confirming that dye production had started there around 1100 BCE. Production intensified with the rise of the Kingdom of Israel and later saw a resurgence during the ᴀssyrian period before declining following the Babylonian conquest around 586 BCE, bringing with it broad economic collapse as well as the destruction of the First Temple in Jerusalem.

More information: Shalvi G, Sukenik N, Waiman-Barak P, Dunseth ZC, Bar S, Pinsky S, et al. (2025) Tel Shiqmona during the Iron Age: A first glimpse into an ancient Mediterranean purple dye ‘factory’. PLoS ONE 20(4): e0321082. doi:10.1371/journal.pone.0321082