Deep, reddish-purple dye and pigment produced from the mucous glands of murex sea snails (family Muricidae). Because it took an estimated 250,000 snails to make half an ounce of Tyrian purple, it was the most expensive colorant in antiquity. It was prized by the ancient Phoenicians and Romans, and became a symbol of high status. The largest ancient manufacturing center was Tyre, in modern-day Lebanon. Tyrian purple was used primarily as a dye for textiles, but Tyrian purple pigment was also used in paint as early as the 17th c. BCE (Saffron-Gatherers fresco from Akrotiri, National Archaeological Museum, Athens). Web resources here and here. Video here.

Photo: Mohammed Ghassen Nouira