Purple of Tyre
Tyre is one of the oldest continuously inhabited cities in the world. One of the best known episodes in Tyrian history is the resistance to Macedonian King Alexander The Great's seven-month siege in 332 BC.
"But Alexander, before he proceeded any further, thought it necessary to assure himself of the sea-coast. Those who governed in Cyprus put that island into his possession, and Phoenicia, Tyre only excepted, was surrendered to him. During the siege of this city, which, with mounds of earth cast up, and battering engines, and two hundred galleys by sea, was carried on for seven months together, he dreamt that he saw Hercules upon the walls, reaching out his hands, and calling to him. And many of the Tyrians in their sleep fancied that Apollo told them he was displeased with their actions, and was about to leave them and go over to Alexander." -Plutarch, Alexander
With the end of the Seleucid Empire, Tyre came under Roman rule (circa 64 BC). The Phoenicians of Tyre were known for their purple dye, a color that became synonymous with imperial authority, prized by the Romans from the early kings through the republic and imperial periods.
Julius Pollux, in his Onomasticon (from Greek Ὀνομαστικόν, loosely translated to "about names"), in the 2nd century AD, wrote that Hercules (Melqart also known as Tyrian Baal) discovered purple dye in pursuit of a nymph with whom he was enamored.
Phoenicia derives from the Greek phoenix, with root phoinos, meaning “red.” This could refer to purple color, to the red-winged bird, to red-faced people and other options and was used by the Greeks to refer to the people from the Levant. The Phoenicians originated in the Levant and the great rival to the Roman republic, Carthage, was founded by Phoenicians from Tyre.
Shells of the "purple dye murex", bolinus brandaris, in Cadiz, Spain. This is one of several species that were used by the Phoenicians in ancient Tyre (modern Lebanon), for their purple dye.
-Julius Pollox, Onomasticon, translated into Latin by Rudolf Gwalther in the 16th century, p.23
Tyrians relate that Hercules fell in love with a native nymph, Tyros, who was followed by a dog. The dog, seeing a purple thing on a rock, seized the protruding flesh and bit it, staining himself with the black blood of the animal. Hercules seeing this was struck by the idea of making a beautiful garment with this dye. He hid the explanation when the nymph noticed the dog's lips dyed an unusual color. Hercules collected the blood of the animal and made his girlfriend a gift. According to the Tyrians, he was the first to discover the color of the Phoenicians. - Julius Pollox, Onomasticon, translated from Latin by the author
Where is Tyre?
The Discovery of Tyrian Purple in Paintings
Peter Paul Rubens painted this story, leaving out the nymph and not correctly representing the type of the shell.
Hercules's Dog Discovers Purple Dye, by Peter Paul Rubens. 28 × 34 cm; oil on panel. Musée Bonnat, Bayonne, France. Public domain image via Wikimedia Commons.
The making of dye
Pliny the Elder relates that a small amount of dye would take thousands of shells, making this purple dye very valuable (impossible to buy for 1000 denarii per pound) . Hypobranchial glands of this mollusk were heated slowly in a lead pot, a process that generated foul smells.
"Subsequently the vein of which we spoke is removed, and to this salt has to be added, about a pint for every hundred pounds; three days is the proper time for it to be steeped (as the fresher the salt the stronger it is), and it should be heated in a leaden pot, and with 50 lbs. of dye to every six gallons of water kept at a uniform and moderate temperature by a pipe brought from a furnace some way off. This will cause it gradually to deposit the portions of flesh which are bound to have adhered to the veins, and after about nine days the cauldron is strained and a fleece that has been washed clean is dipped for a trial, and the liquid is heated up until fair confidence is achieved." -Pliny the Elder, Natural History, IX.LXII
Pliny goes on with much longer description of the dying process and the history of use by the Roman Kings including Romulus' cloak and the "bordered robe and broader purple stripe" used first by King Tullus Hostilius, after the conquest of Etruscans. The title "born in the purple", porphyrogennetos, was taken by Byzantine kings to reflect their royal birth. See a related post on Byzantine emperor Constantine VII.
Some recent science
Tyrian dye is mentioned in the Nature article about a Mediterranean whelk species threatened by global warming: Rilov, G. Multi-species collapses at the warm edge of a warming sea. Nature, Sci Rep 6, 36897 (2016).
One of the primary chemical compounds that makes up this dye is called 6,6'-Dibromoindigo.
Joel L Wolk, and Aryeh A Frimer write of A simple, safe and efficient synthesis of Tyrian purple (6,6'-dibromoindigo), in Molecules 2010 Aug 12; 15(8):5561-80, doi: 10.3390/molecules15085561.
An ancient coin
So I am sure that by now, with chemistry, climate science, and textile lessons, the reader may wonder, "Did I click to the wrong site?". However you can rest assured that there is a coin at the end of this story: a tetradrachm from the reign of Trajan:
Phoenicia, Tyre, Trajan (AD 98-117), AR tetradrachm (25mm, 14.33g, 6h), struck AD 103-109
Obv: AYTOKP KAIC NEP TPAIANOC CEB ΓERM ΔAK, laureate head of Trajan right above eagle standing right; club to right
Rev: ΔHMAPX-EΞ YΠAT•E, laureate bust of Melqart-Herakles right, lion’s skin tied around neck
Ref: Prieur 1495A; McAlee 455A
Herodotus during his visit to Tyre writes in the 5th century BC that Tyre was founded 2,300 years ago. Hercules and Melqart, on the reverse of this coin, are in this text equivalent.
Because I wanted to know more about it, I made a voyage to Tyre in Phoenicia, because I had been told that in that place there was a holy temple of Heracles. The sanctuary was richly furnished, there were many votive offerings, and I noticed two pillars: one of pure gold and one of an emerald stone of such size as to shine by night. -Herodotus, Histories, 2.44
The club on the obverse of this coin was used as a mint mark for Tyre on both the city's autonomous tetradrachms, and on coins of Trajan. During the time in which this coin was issued - Trajan had his significant victories over Dacia (concluded in AD 106). Shortly after the time of this coin, near the end of Trajan's reign, the second Jewish Roman war (Kitos War) erupted in AD 115 during Trajan's Parthian War. Trajan died in AD 117 in Selendi, Turkey in western Asia Minor (Turkey). For more on his death and the transition of power to Hadrian see the related note "Transition of Power".
References and additional reading beyond to those listed in line
an interesting timeline for Tyre from 2750 BC at https://www.historyfiles.co.uk/KingListsMiddEast/CanaanTyre.htm
Mark Cartwright, August 2016, Tyrian Purple at https://www.worldhistory.org/Tyrian_Purple/
Bloedow, E. F., & Bloedow, E. J. (1994). Alexander’s Speech on the Eve of the Siege of Tyre. L’Antiquité Classique, 63, 65–76.
Porphyrogennetos, definition at Dumbarton Oaks
Tyre UNESCO World Heritage site https://whc.unesco.org/en/list/299/
For more on the column of Trajan see : https://smarthistory.org/column-of-trajan/