Tyrian purple

Tyrian purple also known as royal purple, imperial purple or imperial dye, is a purple-red natural dye
Natural dye
Natural dyes are dyes or colorants derived from plants, invertebrates, or minerals. The majority of natural dyes are vegetable dyes from plant sources – roots, berries, bark, leaves, and wood — and other organic sources such as fungi and lichens....

, which is extracted from sea snail
Snail is a common name applied to most of the members of the molluscan class Gastropoda that have coiled shells in the adult stage. When the word is used in its most general sense, it includes sea snails, land snails and freshwater snails. The word snail without any qualifier is however more often...

s, and which was possibly first produced by the ancient Phoenicia
Phoenicia , was an ancient civilization in Canaan which covered most of the western, coastal part of the Fertile Crescent. Several major Phoenician cities were built on the coastline of the Mediterranean. It was an enterprising maritime trading culture that spread across the Mediterranean from 1550...

ns. This dye
A dye is a colored substance that has an affinity to the substrate to which it is being applied. The dye is generally applied in an aqueous solution, and requires a mordant to improve the fastness of the dye on the fiber....

 was greatly prized in antiquity because it did not fade, rather it became brighter and more intense with weathering and sunlight.

Tyrian purple was expensive: the 4th-century-BC
4th century BC
The 4th century BC started the first day of 400 BC and ended the last day of 301 BC. It is considered part of the Classical era, epoch, or historical period.-Overview:This century marked the height of Classical Greek civilization in all of its aspects...

History is the discovery, collection, organization, and presentation of information about past events. History can also mean the period of time after writing was invented. Scholars who write about history are called historians...

Theopompus was a Greek historian and rhetorician- Biography :Theopompus was born on Chios. In early youth he seems to have spent some time at Athens, along with his father, who had been exiled on account of his Laconian sympathies...

 reported, "Purple for dyes fetched its weight in silver at Colophon" in Asia Minor
Asia Minor
Asia Minor is a geographical location at the westernmost protrusion of Asia, also called Anatolia, and corresponds to the western two thirds of the Asian part of Turkey...