View source for Tyrian purple

{{short description|Natural dye extracted from ''Murex'' sea snails}}
[[File:Purple_Purpur_(retouched).jpg|thumb|Fabrics dyed in the current era from different species of sea snail. The colours in this photograph may not represent them precisely.]]
'''Tyrian purple''' ({{lang-grc|πορφύρα}} ''porphúra''; {{lang-la|purpura}}), also known as '''royal purple''', '''imperial purple''', or '''imperial dye''', is a reddish-[[Purple|purple]] [[Chemistry:Natural dye|natural dye]]. The name Tyrian refers to [[Place:Tyre, Lebanon|Tyre, Lebanon]]. It is secreted by several species of predatory [[Biology:Sea snail|sea snail]]s in the family [[Biology:Muricidae|Muricidae]], rock snails originally known by the name Murex (''[[Biology:Bolinus brandaris|Bolinus brandaris]]'', ''[[Biology:Hexaplex trunculus|Hexaplex trunculus]]'' and ''[[Biology:Stramonita haemastoma|Stramonita haemastoma]]''). In ancient times, extracting this dye involved tens of thousands of snails and substantial labour, and as a result, the dye was highly valued. The [[Chemistry:Chromophore|colored compound]] is [[Chemistry:6,6′-Dibromoindigo|6,6′-dibromoindigo]].

==History==
[[File:PM 110511 Liebig Chromos.jpg|thumb|A twentieth-century depiction of a Roman triumph celebrated by Julius Caesar. Caesar, riding in the chariot, wears the solid Tyrian purple ''toga picta''. In the foreground, two Roman magistrates are identified by their ''toga praetexta'', white with a stripe of Tyrian purple.]]

Biological pigments were often difficult to acquire, and the details of their production were kept [[Social:Trade secret|secret]] by the manufacturers. Tyrian purple is a pigment made from the [[Biology:Mucus|mucus]] of several species of [[Biology:Hexaplex trunculus|Murex snail]]. Production of Tyrian purple for use as a fabric dye began as early as 1200 BC by the [[History:Phoenicia|Phoenicia]]ns, and was continued by the Greeks and [[Place:Byzantine Empire|Romans]] until 1453 AD, with the fall of Constantinople. In the same way as the modern-day Latin alphabet of Phoenician origin, Phoenician purple pigment was spread through the unique Phoenician trading empire.<ref name="ruthg">{{cite book |title=Dyes: From Sea Snails to Synthetics |author=Kassinger, Ruth G. |date=6 February 2003 |publisher=21st century |url=https://archive.org/details/dyesfromseasnail0000kass |url-access=registration |isbn=0-7613-2112-8 }}</ref> The pigment was expensive and time-consuming to produce, and items colored with it became associated with power and wealth. This popular idea of purple being elite contributes to the modern day wide-spread belief that purple is a "royal colour". The colour of textiles from this period provides insight into socio-cultural relationships within ancient societies, in addition to providing insights on technological achievements, fashion, social stratification, agriculture and trade connections.<ref name=NS>{{cite journal |last1=Sukenik |first1=Naama |last2=Iluz |first2=David |last3=Amar |first3=Zohar |last4=Varvak |first4=Alexander |last5=Shamir |first5=Orit |last6=Ben-Yosef |first6=Erez |title=Early evidence of royal purple dyed textile from Timna Valley (Israel) |journal=PLOS ONE |date=28 January 2021 |volume=16 |issue=1 |pages=e0245897 |doi=10.1371/journal.pone.0245897|pmid=33507987 |pmc=7842898 |bibcode=2021PLoSO..1645897S |language=en |issn=1932-6203|doi-access=free}}</ref>  Despite their value to archaeological research, textiles are quite rare in the archaeological record. Like any perishable organic material, they are usually subject to rapid decomposition and their preservation over millennia requires exacting conditions to prevent destruction by microorganisms.<ref name=NS/>

Tyrian purple may first have been used by the ancient [[History:Phoenicia|Phoenicia]]ns as early as 1570&nbsp;BC.<ref>McGovern, P. E. and Michel, R. H. "Royal Purple dye: tracing the chemical origins of the industry". ''Analytical Chemistry'' 1985, 57, 1514A–1522A</ref><ref name="StClair">{{Cite book|title=The Secret Lives of Colour| vauthors = St Clair K |publisher=John Murray|year=2016|isbn=9781473630819|location=London|pages=162–164|oclc=936144129}}</ref> It has been suggested that the name Phoenicia itself means 'land of purple'.<ref>{{cite book |author=Cunliffe, Barry |title=Europe between the Oceans: 9000&nbsp;BC – AD&nbsp;1000 |location=New Haven, Connecticut |publisher=Yale University Press |year=2008 |page=241}}</ref><ref>{{cite web |url=http://www.etymonline.com/index.php?term=Phoenician |title=Phoenician |website=Online Etymology Dictionary}}</ref> The dye was greatly prized in antiquity because the colour did not easily fade, but instead became brighter with weathering and sunlight. It came in various shades, the most prized being that of black-tinted clotted blood.<ref name=Pigments_WebExhibits>{{cite web |url=http://www.webexhibits.org/causesofcolor/7.html |title=Pigments: Causes of Color |website=WebExhibits.org |access-date=2016-06-10 |df=dmy-all}}</ref><ref name="StClair" />

Because it was extremely tedious to make, Tyrian purple was expensive: the 4th&nbsp;century&nbsp;BC historian Theopompus reported, "Purple for dyes fetched its weight in silver at Colophon" in [[Earth:Asia Minor|Asia Minor]].<ref>Theopompus, cited by Athenaeus (12:526) around 200&nbsp;BC.{{cite book |translator=Gulick, Charles Barton |year=1941 |author=Athenaeus |title=The Deipnosophists |location=Cambridge, Massachusetts |publisher=Harvard University Press}}</ref> The expense meant that purple-dyed textiles became [[Philosophy:Status symbol|status symbol]]s, whose use was restricted by sumptuary laws. The most senior Roman magistrates wore a ''toga praetexta'', a white toga edged in Tyrian purple. The even more sumptuous ''toga picta'', solid Tyrian purple with gold thread edging, was worn by generals celebrating a Roman triumph.<ref name="StClair" /> 

By the fourth century AD, sumptuary laws in Rome had been tightened so much that only the Roman emperor was permitted to wear Tyrian purple.<ref name="StClair" /> As a result, 'purple' is sometimes used as a metonym for the office (e.g. the phrase 'donned the purple' means 'became emperor'). The production of Tyrian purple was tightly controlled in the succeeding [[Place:Byzantine Empire|Byzantine Empire]] and subsidized by the imperial court, which restricted its use for the colouring of [[History:Byzantine silk|imperial silks]].<ref>{{cite book | vauthors = Jacoby D |article=Silk in Western Byzantium before the Fourth Crusade |title=Trade, Commodities, and Shipping in the Medieval Mediterranean |year=1997 |at=pp.&nbsp;455&nbsp;ff and notes&nbsp;[17]–[19]}}</ref> Later (9th&nbsp;century), a child born to a reigning emperor was said to be ''porphyrogenitos'', "born in the purple".<ref>{{cite book |article=Porphyrogennetos |title=The Oxford Dictionary of Byzantium |publisher=Oxford University Press |location=New York and Oxford, UK |year=1991 |page=1701 |isbn=0-195-04652-8}}</ref>

Some{{Who?|date=March 2017}} speculate that the dye extracted from the ''[[Biology:Bolinus brandaris|Bolinus brandaris]]'' is known as {{transl|hbo|argaman}} ({{lang|hbo|ארגמן}}) in [[Social:Biblical Hebrew|Biblical Hebrew]]. Another dye extracted from a related sea snail, ''[[Biology:Hexaplex trunculus|Hexaplex trunculus]]'', produced a blue colour after light exposure which could be the one known as {{transl|hbo|[[Tekhelet|tekhelet]]}} ({{lang|hbo|תְּכֵלֶת}}), used in garments worn for ritual purposes.<ref>{{cite journal | vauthors = Elsner O |title=Solution of the enigmas of dyeing with Tyrian purple and the Biblical tekhelet |journal=Dyes in History and Archaeology |volume=10 |year=1992 |at=pages&nbsp;14&nbsp;ff}}</ref>

==Production from sea snails==
[[File:Haustellum brandaris 000.jpg|thumb|Two [[Biology:Gastropod shell|shells]] of ''Bolinus brandaris'', the spiny dye-murex, a source of the dye]]

The dye substance is a mucous secretion from the [[Biology:Hypobranchial gland|hypobranchial gland]] of one of several species of medium-sized predatory [[Biology:Sea snail|sea snail]]s that are found in the eastern [[Place:Mediterranean Sea|Mediterranean Sea]], and off the Atlantic coast of Morocco. These are the [[Earth:Ocean|marine]] gastropods ''[[Biology:Bolinus brandaris|Bolinus brandaris]]'' the spiny dye-murex (originally known as ''Murex brandaris'' Linnaeus, 1758), the banded dye-murex ''[[Biology:Hexaplex trunculus|Hexaplex trunculus]]'', the rock-shell ''[[Biology:Stramonita haemastoma|Stramonita haemastoma]]'',<ref>{{cite journal |author=Ziderman, I.I. |year=1986 |title=Purple dye made from shellfish in antiquity |journal=Review of Progress in Coloration |volume=16 |pages=46–52|doi=10.1111/j.1478-4408.1986.tb03743.x }}</ref><ref name="Radwin, G. E 1986. p93">{{cite book |author1=Radwin, G. E. |author2=D'Attilio, A. |year=1986 |title=Murex shells of the world. An illustrated guide to the Muricidae |page=93 |publisher=Stanford University Press |location=Stanford, CA}} 284&nbsp;pp incl 192&nbsp;figs. & 32&nbsp;pls.</ref> and less commonly a number of other species such as ''[[Biology:Bolinus cornutus|Bolinus cornutus]]''. The dye is an organic compound of [[Chemistry:Bromine|bromine]] (i.e., an [[Chemistry:Organobromine compound|organobromine compound]]), a class of compounds often found in algae and in some other sea life, but much more rarely found in the biology of land animals. This dye is in contrast to the cheaper imitation purple that was commonly produced using cheaper materials than the dyes from the sea snail.<ref name=NS/>

In nature, the snails use the secretion as part of their predatory behavior to sedate prey and as an [[Biology:Antimicrobial|antimicrobial]] lining on egg masses.<ref name="Benkendorff">{{cite thesis | vauthors = Benkendorff K |title=Bioactive molluscan resources and their conservation: Biological and chemical studies on the egg masses of marine molluscs |publisher=University of Wollongong |date=March 1999 |url=http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20011204.154039/index.html |format=PDF |access-date=2008-02-25 |archive-url=https://web.archive.org/web/20070830143907/http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20011204.154039/index.html <!-- Bot retrieved archive --> |archive-date=2007-08-30 |df=dmy-all}}</ref><ref group="lower-alpha">Because of research by Benkendorff et al. (1999), the Tyrian purple precursor tyrindoleninone is being investigated as a potential antimicrobial agent with uses against [[Biology:Multidrug-resistant bacteria|multidrug-resistant bacteria]].</ref> The snail also secretes this substance when it is attacked by predators, or physically antagonized by humans (e.g., poked). Therefore, the dye can be collected either by "milking" the snails, which is more labor-intensive but is a renewable resource, or by collecting and destructively crushing the snails. David Jacoby remarks that "twelve thousand snails of ''Murex brandaris'' yield no more than 1.4&nbsp;g of pure dye, enough to colour only the trim of a single garment."<ref>{{cite journal | vauthors = Jacoby D |title=Silk economics and cross-cultural artistic interaction: Byzantium, the Muslim world, and the Christian west |journal=Dumbarton Oaks Papers |volume=58 |year=2004 |pages=210, 197–240|doi=10.2307/3591386 |jstor=3591386 }}</ref> Through the snail harvesting process which includes the extraction of the hypobranchial gland (located under the mollusk's mantle) the dye is collected which required advanced knowledge of biology. Murex-based dyeing must take place close to the site from which the snails originate, because the freshness of the material has a significant effect on the results, the colors yielded based on the long process of biochemical, enzymatic and photochemical reactions, and requires reduction and oxidation processes that probably took several days.<ref name=NS/>

Many other species worldwide within the family Muricidae, for example ''[[Biology:Plicopurpura pansa|Plicopurpura pansa]]'',<ref>{{cite journal | vauthors = Gould AA |title=Descriptions of shells from the Gulf of California and the Pacific coasts of Mexico and California |journal=Boston Journal of Natural History |date=1853 |volume=6 |pages=374–408 |url=https://babel.hathitrust.org/cgi/pt?id=pst.000018613018&view=1up&seq=402}} ; see pp. 406–407.  Note:  Gould called this species ''Purpura pansa'' ; it was later renamed ''Plicopurpura pansa''.</ref> from the tropical eastern Pacific, and ''[[Biology:Plicopurpura patula|Plicopurpura patula]]''<ref>''Plicopurpura patula'' was originally named ''Buccinum patulum'' by Linnaeus in 1758:
* {{cite book | vauthors = von Linné C |title=Systema naturæ per regna tria naturæ … |date=1758 |volume=1 |publisher=Lars Salvius |location=Stockholm, Sweden |page=739 |url=https://www.biodiversitylibrary.org/item/10277#page/761/mode/1up |language=la}}
*World Register of Marine Species (Web site): [http://www.marinespecies.org/aphia.php?p=taxdetails&id=396994 ''Plicopurpura patula'' (Linnaeus, 1758).]
The genus ''Plicopurpura'' was created in 1903 by Cossmann:
* {{cite book | vauthors = Cossmann M |title=Essais de paléoconchologie comparée |date=1903 |publisher=(Self-published) |location=Paris, France |volume= 5 |pages=68–69 |url=https://www.biodiversitylibrary.org/item/112977#page/80/mode/1up |language=fr}}</ref> from the Caribbean zone of the western Atlantic, can also produce a similar substance (which turns into an enduring purple dye when exposed to sunlight) and this ability has sometimes also been historically exploited by local inhabitants in the areas where these snails occur. (Some other predatory gastropods, such as some [[Biology:Wentletrap|wentletrap]]s in the family Epitoniidae, seem to also produce a similar substance, although this has not been studied or exploited commercially.) The [[Biology:Dog whelk|dog whelk]] ''Nucella lapillus'', from the North Atlantic, can also be used to produce red-purple and violet dyes.<ref>{{cite journal |title=Whelks and purple dye in Anglo-Saxon England | vauthors = Biggam CP |publisher=Department of English Language, University of Glasgow |location=Glasgow, Scotland, UK |journal=The Archaeo+Malacology Group Newsletter |issue=9 |date=March 2006 |url=http://triton.anu.edu.au/MalacGp09.pdf}}</ref>

==Royal blue==
The Phoenicians also made a deep blue-coloured dye, sometimes referred to as ''royal blue'' or ''hyacinth purple'', which was made from a closely related species of marine snail.<ref name=Moorey1999>{{cite book |title=Ancient Mesopotamian Materials and Industries: The Archaeological Evidence | vauthors = Moorey P |publisher=Eisenbrauns |location=Winona Lake, Indiana |year=1999 |isbn=1-57506-042-6 |page=138}}</ref>

The Phoenicians established an ancillary production facility on the Iles Purpuraires at Mogador, in Morocco.<ref>{{cite web | vauthors = Hogan CM |title=Mogador: Promontory Fort |website=The Megalithic Portal | veditors = Burnham A |date=2 November 2007 |url=http://www.megalithic.co.uk/article.php?sid=17926}}</ref> The sea snail harvested at this western Moroccan dye production facility was ''[[Biology:Hexaplex trunculus|Hexaplex trunculus]]'', also known by the older name ''Murex trunculus''.<ref>In 1758, Linnaeus classified the snail as ''Murex trunculus'':
* {{cite book |vauthors = von Linné C |title=Systema naturae per regna tria naturae … |date=1758 |volume=v.1 |publisher=Lars Salvius |location=Stockholm, Sweden |page=747 |url=https://www.biodiversitylibrary.org/item/10277#page/769/mode/1up |language=la}}
In 1810, the English naturalist George Perry created the genus ''Hexaplex'':
* {{cite book | vauthors = Perry G |title=Arcana, or, The museum of natural history … |date=1810–1811 |publisher=James Stratford |location=London, England |page=Plate XXIII: Genus: Triplex |url=https://archive.org/details/arcanaormuseumof00perr/page/n139}}
* {{cite journal | vauthors = Mathews GM, Iredale T |title="Perry's Arcanda" – an overlooked work |journal=The Victorian Naturalist |date=May 1912 |volume=29 |issue=1 |pages=7–16 |url=https://www.biodiversitylibrary.org/item/38346#page/19/mode/1up}} ; see p. 11.
*[http://www.marinespecies.org/aphia.php?p=taxdetails&id=138194 World Register of Marine Species (Web site): ''Hexaplex'' Perry, 1810]</ref>

This second species of dye murex is found today on the Mediterranean and Atlantic coasts of Europe and Africa (Spain, Portugal, Morocco).<ref name="Radwin, G. E 1986. p93"/>

== Background ==
[[File:Mosaic of Justinianus I - Basilica San Vitale (Ravenna).jpg|thumb|Byzantine Emperor Justinian I clad in Tyrian purple, 6th-century mosaic at Basilica of San Vitale, Ravenna, Italy]]

The colour-fast (non-fading) dye was an item of luxury trade, prized by [[History:Ancient Rome|Romans]], who used it to colour ceremonial robes. Used as a dye, the colour shifts from blue (peak absorption at 590&nbsp;nm, which is yellow-orange) to reddish-purple (peak absorption at 520&nbsp;nm, which is green).<ref>{{cite journal | vauthors = Cooksey CJ |title=Tyrian purple: 6,6'-dibromoindigo and related compounds |journal=Molecules |year=2001 |volume=6 |issue=9 |pages=736–769|pmc=6236399 | doi=10.3390/60900736 |doi-access=free }}</ref> It is believed that the intensity of the purple hue improved rather than faded as the dyed cloth aged. Vitruvius mentions the production of Tyrian purple from shellfish.<ref>{{cite book |author=Vitruvius |title=De Architectura |trans-title=On Architecture |url=https://penelope.uchicago.edu/Thayer/E/Roman/Texts/Vitruvius/7*.html |at=Book VII, Chapter 13}}</ref> In his ''[[Philosophy:History of Animals|History of Animals]]'', [[Biography:Aristotle|Aristotle]] described the shellfish from which Tyrian purple was obtained and the process of extracting the tissue that produced the dye.<ref>{{cite book |author=Aristotle |title=History of Animals |location=Whitefish, MT |publisher=Kessering Publishing |year=2004 |at=Book&nbsp;V, pages&nbsp;131–132 |url=https://books.google.com/books?id=Dma7o9N6zWkC&q=stains&pg=PA132|isbn=9781419123917 }}</ref> Pliny the Elder described the production of Tyrian purple in his ''Natural History'':<ref>{{cite book |author=Pliny the Elder |title=The Natural History |editor1-link=John Bostock (physician) | veditors = Bostock J, Riley HT |editor2-link=Henry Thomas Riley  |location=London, UK |publisher=Taylor and Francis |year=1855 |at=Book IX |chapter=Chapter&nbsp;62: ''The Natural History of Fishes'' |chapter-url=https://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.02.0137%3Abook%3D9%3Achapter%3D62}} Pliny discusses Tyrian purple throughout Chapters&nbsp;60–65.</ref><ref group=lower-alpha>The problem with Tyrian purple is that the precursor reacts very quickly with air and light to form an insoluble dye. (Hence Pliny says: "...&nbsp;''when [the shellfish] have once discharged their waxy secretion, their juices have no consistency''.&nbsp;...") The cumbersome process that Pliny describes is necessary to reverse the oxidation and to restore the water-soluble precursor so that large masses of wool can be dyed. See: {{cite journal | vauthors = Biggam CP |year=2006 |title=Knowledge of whelk dyes and pigments in Anglo-Saxon England |journal=Anglo-Saxon England |volume=35 |at=pages&nbsp;23–56; see especially pages&nbsp;26–27 |url=https://books.google.com/books?id=ZojyGIfG9m4C&q=soluble+insoluble&pg=PA26|isbn=9780521883429 |doi=10.1017/S0263675106000032 |s2cid=162937239 }} See also: C. J. Cooksey (2001) "Tyrian purple: 6,6’-Dibromoindigo and Related Compounds," ''Molecules'',  '''6''' (9) : 736–769, especially page 761. Indigo, which is chemically very similar to Tyrian purple, behaves similarly. See: http://www.indigopage.com/chemistry.htm</ref>

<blockquote>The most favourable season for taking these [shellfish] is after the rising of the [[Astronomy:Sirius|Dog-star]], or else before spring; for when they have once discharged their waxy secretion, their juices have no consistency: this, however, is a fact unknown in the dyers' workshops, although it is a point of primary importance. After it is taken, the vein [i.e. hypobranchial gland] is extracted, which we have previously spoken of, to which it is requisite to add salt, a sextarius [about 20&nbsp;fl.&nbsp;oz.] to every hundred pounds of juice. It is sufficient to leave them to steep for a period of three days, and no more, for the fresher they are, the greater virtue there is in the liquor. It is then set to boil in vessels of tin [or lead], and every hundred amphorae ought to be boiled down to five hundred pounds of dye, by the application of a moderate heat; for which purpose the vessel is placed at the end of a long funnel, which communicates with the furnace; while thus boiling, the liquor is skimmed from time to time, and with it the flesh, which necessarily adheres to the veins. About the tenth day, generally, the whole contents of the cauldron are in a liquefied state, upon which a fleece, from which the grease has been cleansed, is plunged into it by way of making trial; but until such time as the colour is found to satisfy the wishes of those preparing it, the liquor is still kept on the boil. The tint that inclines to red is looked upon as inferior to that which is of a blackish hue. The wool is left to lie in soak for five hours, and then, after carding it, it is thrown in again, until it has fully imbibed the colour.</blockquote>

Archaeological data from [[Place:Tyre, Lebanon|Tyre]] indicate that the snails were collected in large vats and left to decompose. This produced a hideous stench that was actually mentioned by ancient authors. Not much is known about the subsequent steps, and the actual ancient method for mass-producing the two murex dyes has not yet been successfully reconstructed; this special "blackish clotted blood" colour, which was prized above all others, is believed to be achieved by double-dipping the cloth, once in the indigo dye of ''H.&nbsp;trunculus'' and once in the purple-red dye of ''B.&nbsp;brandaris''.<ref name=Pigments_WebExhibits/><ref name=Moorey1999 />

[[File:Theodoor van Thulden - The Discovery of Purple.jpg|thumb|''The Discovery of Purple by Hercules's Dog'' by Theodoor van Thulden, c. 1636]]
[[File:OldGreekPhoenikianCoinPurpur2000.jpg|thumb|A [[History:Phoenicia|Phoenician]] coin depicting the legend of the dog biting the sea snail]]

The Roman mythographer Julius Pollux, writing in the 2nd&nbsp;century&nbsp;AD, asserted (''Onomasticon'' I, 45–49) that the purple dye was first discovered by the philosopher Heracles of Tyre, or rather, by his dog, whose mouth was stained purple from chewing on snails along the coast at Tyre. This story was depicted by Peter Paul Rubens in his painting ''Hercules' Dog Discovers Purple Dye''. According to John Malalas, the incident happened during the reign of the legendary King Phoenix of Tyre, the eponymous progenitor of the Phoenicians, and therefore he was the first ruler to wear Tyrian purple and legislate on its use.<ref>John Malalas, ''Chronographia'' II:9.</ref>

Recently, the archaeological discovery of substantial numbers of Murex shells on Crete suggests that the Minoans may have pioneered the extraction of Imperial purple centuries before the Tyrians. Dating from collocated pottery suggests the dye may have been produced during the Middle Minoan period in the 20th–18th&nbsp;century&nbsp;BC.<ref>Reese, David S. (1987). "Palaikastro Shells and Bronze Age Purple-Dye Production in the Mediterranean Basin," ''Annual of the British School of Archaeology at Athens'', '''82''', 201–206</ref><ref>Stieglitz, Robert R. (1994), "The Minoan Origin of Tyrian Purple," ''Biblical Archaeologist'', '''57''', 46–54.</ref> Accumulations of crushed murex shells from a hut at the site of Coppa Nevigata in southern Italy may indicate production of purple dye there from at least the 18th&nbsp;century&nbsp;BC.<ref>{{cite book | vauthors = Cazzella A, Moscoloni M |year=1998 |article=Coppa Nevigata: un insediamento fortificato dell'eta del Bronzo | veditors = Troccoli LD |title=Scavi e ricerche archeologiche dell'Università di Roma La Sapienza |url=https://books.google.com/books?id=Zcc5P5hqsu8C&pg=PA178 |pages=178–179|isbn=9788882650155 }}</ref> Additional archaeological evidence can be found from samples originating from excavations at the extensive Iron Age copper smelting site of “Slaves’ Hill” (Site 34), which is tightly dated by radiocarbon to the late 11th–early 10th centuries BC.<ref name=NS/> Findings from this site include evidence of the use of purple dye found in stains used on pot shards. Evidence of the use of dye in pottery are found in most cases on the upper part of ceramic basins, on the inside surface, the areas in which the reduced dye-solution was exposed to air, and underwent oxidation that turned it purple.<ref name=NS/>

The production of ''Murex'' purple for the Byzantine court came to an abrupt end with the sack of Constantinople in 1204, the critical episode of the Fourth Crusade. David Jacoby concludes that "no Byzantine emperor nor any Latin ruler in former Byzantine territories could muster the financial resources required for the pursuit of murex purple production. On the other hand, murex fishing and dyeing with genuine purple are attested for Egypt in the tenth to 13th centuries."<ref>Jacoby (2004), p.&nbsp;210.</ref> By contrast, Jacoby finds that there are no mentions of purple fishing or dyeing, nor trade in the colorant in any Western source, even in the Frankish Levant. The European West turned instead to [[Chemistry:Vermilion|vermilion]] provided by the insect ''[[Biology:Kermes vermilio|Kermes vermilio]]'', known as ''grana'', or [[Crimson|crimson]].

In 1909, Harvard anthropologist Zelia Nuttall compiled an intensive comparative study on the historical production of the purple dye produced from the carnivorous murex snail, source of the royal purple dye valued higher than gold in the ancient Near East and ancient Mexico.  Not only did the people of ancient Mexico use the same methods of production as the Phoenicians, they also valued murex-dyed cloth above all others, as it appeared in codices as the attire of nobility. "Nuttall noted that the Mexican murex-dyed cloth bore a "disagreeable … strong fishy smell, which appears to be as lasting as the color itself."<ref>{{cite book | vauthors = Nutall Z |chapter=A curious survival in Mexico of the use of the Purpura shell-fish for dyeing | veditors = Boas F |title=Anthropological Essays Presented to Fredrick Ward Putnam in Honor of his Seventieth Birthday, by his Friends and Associates |publisher=G. E. Strechert & Co. |location=New York, New York |date=1909 |chapter-url=https://babel.hathitrust.org/cgi/pt?id=njp.32101079830103;view=1up;seq=460 |page=370}}</ref> Likewise, the ancient Egyptian ''Papyrus of Anastasi'' laments: "The hands of the dyer reek like rotting fish&nbsp;..."<ref name="robinson">{{cite book | vauthors = Robinson S |title=A History of Dyed Textiles |date=1969 |publisher=Studio Vista |location=London, UK |page=24}}</ref> So pervasive was this stench that the Talmud specifically granted women the right to divorce any husband who became a dyer after marriage.<ref>{{cite book | vauthors = Compton S |title=Exodus Lost |date=2010 |publisher=Booksurge Publishing |isbn=9781439276839 |pages=29–33 |edition=1st |url=https://books.google.com/books?isbn=1439276838}}</ref>

In 2021, archaeologists found surviving wool fibers dyed with royal purple in the Timna Valley in Israel. The find, which was dated to c. 1000 BC, constituted the first direct evidence of fabric dyed with the pigment from antiquity.<ref>{{cite news| vauthors = Woode D |date=29 January 2021|title='Regal' purple dye is found in Israeli artefacts dating 3,000 years to the reigns of kings Solomon and David|url=https://www.msn.com/en-us/lifestyle/style/regal-purple-dye-is-found-in-israeli-artefacts-dating-3000-years-to-the-reigns-of-kings-solomon-and-david/ar-BB1dbwDu?ocid=uxbndlbing|work=MSN|access-date=29 Jan 2021}}</ref>

== Murex purple production in North Africa ==
[[File:Tyrian-Purple.svg|thumb|The chemical structure of 6,6′-dibromoindigo, the main component of Tyrian purple]]

Murex purple was a very important industry in many Phoenician territories and [[History:Ancient Carthage|Carthage]] was no exception. Traces of this once very lucrative industry are still visible in many Punic sites such as Kerkouane, Zouchis, Djerba and even in Carthage itself. According to Pliny, Meninx (today's Djerba) produced the best purple in Africa which was also ranked second only after Tyre's. It was found also at Essaouira (Morocco). The Royal purple or Imperial purple<ref>{{cite web |url=https://www.worldhistory.org/Tyrian_Purple/ |title=Definition of the Tyrian purple |language=en |website=[[Organization:World History Encyclopedia|World History Encyclopedia]] |archive-url=https://web.archive.org/web/20160724031543/https://www.ancient.eu/Tyrian_Purple |archive-date=2016-07-24 |url-status=live |df=dmy-all}}</ref> was probably used until the time of [[Biography:Augustine of Hippo|Augustine of Hippo]] (354–430) and before the demise of the Roman Empire.

==Dye chemistry==

Variations in colours of "Tyrian purple" from different snails are related to the presence of indigo dye (blue), 6-bromoindigo (purple), and the red 6,6′-dibromoindigo. Additional changes in colour can be induced by debromination from light exposure (as is the case for [[Tekhelet]]) or by heat processing.<ref name="indigo-bromo">{{cite journal | vauthors = Ramig K, Lavinda O, Szalda DJ, Mironova I, Karimi S, Pozzi F, Shah N, Samson J, Ajiki H, Massa L, Mantzouris D | display-authors = 6 |title=The nature of thermochromic effects in dyeings with indigo, 6-bromoindigo, and 6,6′-dibromoindigo, components of Tyrian purple |journal=Dyes and Pigments |date=June 2015 |volume=117 |pages=37–48 |doi=10.1016/j.dyepig.2015.01.025}}</ref> The final shade of purple is decided by chromatogram, which can be identified by HPLC analysis in a single measurement: indigotin (IND) and [[Chemistry:Indirubin|indirubin]] (INR). The two are found in plant sources such as woad (''Isatis tinctoria L''.) and the indigo plant (''Indigofera tinctoria L''), as well as in several species of shellfish.<ref name=NS/>

In 1998, by means of a lengthy trial and error process, a process for dyeing with Tyrian purple was rediscovered.<ref>{{cite book | vauthors = Edmonds J |title=Tyrian or Imperial Purple: The Mystery of Imperial Purple Dyes |series=Historic Dye Series, no. 7 |location=Little Chalfont, Buckinghamshire, England |publisher=John Edwards |date=2000 |oclc=45315310 |isbn=9780953413362}}</ref><ref>{{cite web |url=http://www.imperial-purple.com/profile.html |title=Author Profile |work=Imperial-Purple.com |access-date=2011-07-13 |url-status=dead |archive-url=https://web.archive.org/web/20110713022226/http://www.imperial-purple.com/profile.html |archive-date=2011-07-13 |df=dmy-all}}</ref> This finding built on reports from the 15th century to the 18th century and explored the biotechnology process behind [[Biology:Isatis tinctoria|woad]] fermentation. It is hypothesized that an alkaline fermenting vat was necessary. An incomplete ancient recipe for Tyrian purple recorded by Pliny the Elder was also consulted. By altering the percentage of sea salt in the dye vat and adding [[Chemistry:Potash|potash]], he was able to successfully dye wool a deep purple colour.<ref>{{cite book |author=Chenciner, Robert |title=Madder Red: A history of luxury and trade: plant dyes and pigments in world commerce and art |location=Richmond |publisher=Curzon Press |year=2000 |page=295}}</ref>

Recent research in [[Chemistry:Organic electronics|organic electronics]] has shown that Tyrian purple is an ambipolar [[Chemistry:Organic semiconductor|organic semiconductor]]. Transistors and circuits based on this material can be produced from sublimed thin-films of the dye. The good semiconducting properties of the dye originate from strong intermolecular hydrogen bonding that reinforces pi stacking necessary for transport.<ref>{{cite journal |title=Ambipolar organic field effect transistors and inverters with the natural material Tyrian purple | vauthors = Głowacki ED, Leonat L, Voss G, Bodea MA, Bozkurt Z, Ramil AM, Irimia-Vladu M, Bauer S, Sariciftci NS | display-authors = 6 |journal=AIP Advances |volume=1 |issue=4 |at=042132 |year=2011 |url=http://aipadvances.aip.org/resource/1/aaidbi/v1/i4/p042132_s1|doi=10.1063/1.3660358 |bibcode=2011AIPA....1d2132G |doi-access=free }}</ref>

== Modern hue rendering ==
True Tyrian purple, like most high-chroma pigments, cannot be accurately rendered on a standard RGB computer monitor. Ancient reports are also not entirely consistent, but these swatches give a rough indication of the likely range in which it appeared:

<span style="background-color:#b80049">_________</span> <br>
<span style="background-color:#990024">_________</span>

The lower one is the [[SRGB|sRGB]] colour #990024, intended for viewing on an output device with a [[Physics:Gamma correction|gamma]] of 2.2&nbsp;. It is a representation of RHS colour code 66A,<ref>{{cite web |title=RHS, UCL and RGB Colors, gamma&nbsp;=&nbsp;1.4, fan&nbsp;2 |website=Azalea Society of America |url=http://www.azaleas.org/index.pl/rhsmacfan2.html |access-date=2006-07-15 |url-status=dead |archive-url=https://web.archive.org/web/20070311031344/http://www.azaleas.org/index.pl/rhsmacfan2.html |archive-date=2007-03-11 |df=dmy-all}} (this gives the RGB value #b80049, which has been converted to #990024 for the sRGB gamma of 2.2)</ref> which has been equated to "Tyrian red",<ref>{{cite web |url=http://www.ag.iastate.edu/centers/cad/Eroses.html |author=Buck, G. |title=Buck Rose |page=5 |archive-url=https://web.archive.org/web/20060823170307/http://www.ag.iastate.edu/centers/cad/Eroses.html |archive-date=2006-08-23 |df=dmy-all}}</ref> a term which is often used as a synonym for Tyrian purple.

==Philately==
The colour name "Tyrian plum" is popularly given to a British postage stamp that was prepared, but never released to the public, shortly before the death of King Edward VII in 1910.<ref>{{cite web |url=http://catalogue.postalmuseum.org/collections/getrecord/GB813_P_150_02_01_21 |website=Postal Museum |series=Collection catalog |title=Edward VII 2d}}</ref>

==Gallery==
<gallery widths="190px" heights="180px">
File:Cuneiform tablet BM62788.jpg|alt=cuneiform tablet|[[Social:Cuneiform|Cuneiform]] tablet, dated 600–500&nbsp;BC, with instructions for dyeing wool purple and blue. Ref.{{British-Museum-db|BM62788|id=327282}}.
File:Heb cover hi.jpg|A set of ''Tzitzit'', four tassels or "fringes" with [[Tekhelet|tekhelet]] (purple-blue) threads produced from a ''Hexaplex trunculus'' based dye.
File:Contemporary portrayal of a toga picta.jpg| Painting of a man wearing an all-purple ''toga picta'', from an [[Place:Etruscan civilization|Etruscan]] tomb (about 350&nbsp;BC).
File:Compitalia fresco.jpg|Roman men wearing ''togae praetextae'' with reddish-purple stripes during a religious procession (1st&nbsp;century&nbsp;BC).
File:Empress Theodora.jpg|The Empress Theodora, the wife of the Emperor Justinian, dressed in Tyrian purple. (6th&nbsp;century).
File:Karl den store krons av leo III.jpg|A medieval depiction of the coronation of the Emperor Charlemagne in 800&nbsp;AD wearing royal blue. The bishops and cardinals wear Tyrian purple, and the Pope wears white.
File:Shroud of Charlemagne manufactured in Constantinople 814.jpg|A fragment of the shroud in which the Emperor Charlemagne was buried in 814&nbsp;AD. It was made of gold and Tyrian purple from Constantinople.
File:Tyrian purple on grayscale.jpg|6,6'-dibromoindigo, the major component of Tyrian purple
</gallery>

== See also ==
* {{annotated link|Biology:Bolinus brandaris|''Bolinus brandaris''}}
* {{annotated link|Biology:Hexaplex trunculus|''Hexaplex trunculus''}}
* {{annotated link|Chemistry:Indigo dye}}
* {{annotated link|Tekhelet}}

== Explanatory notes ==
{{notelist}}

== References ==
{{reflist}}

== External links ==
* {{cite web |url=https://www.worldhistory.org/Tyrian_Purple/ |title=Tyrian Purple |website=[[Organization:World History Encyclopedia|World History Encyclopedia]]}}
* {{cite journal |url=http://www.chriscooksey.demon.co.uk/tyrian/cjcbiblio.html |quote=Source of article in author’s ''Bibliography'' page. | vauthors = Cooksey CJ |year=1994 |title=Making Tyrian purple |journal=Dyes in History and Archaeology |volume=13 |pages=7–13 (email the author for a copy)}}
* {{cite thesis | vauthors = Guckelsberger M |title=Purple Murex Dye in Antiquity |date=December 2013 |url=https://skemman.is/bitstream/1946/16925/1/Purple%20Murex%20Dye%20in%20Antiquity.pdf |publisher=University of Iceland}}
* {{cite web |url=http://www.thefreelibrary.com/Plicopurpura+pansa+(Gould,+1853)+from+the+Pacific+Coast+of+Mexico+and...-a0118543935 |website=The Free Library |title=Tyrian purple}}
* {{cite web |url=http://tekhelet.com/pdf/Jenson-RoyalPurple-1963.pdf |title=Royal Purple of Tyre}}

{{Shades of red}}
{{Shades of violet}}

{{DEFAULTSORT:Tyrian Purple}}
[[Category:Organobromides]]
[[Category:Halogen-containing natural products]]
[[Category:Shades of violet]]

{{Sourceattribution|Tyrian purple}}