Since time immemorial attractive colours have held man's attention. Occasionally he has assigned to them symbolic significance, often as religious or status insignia. The various shades of reds and purples have been especially chosen; some see in them the colour of blood, the sun or fire. The presence of ochre and haematite in Palaeolithic burials may be the first instance of the high regard for these colours.
Probably the most famous red–purple colour associated with religion, status and general elitism is the shell-based purple-dye of the ancient Mediterranean, known variously as Royal purple, Tyrian purple or Imperial purple. The recent discovery of crushed purple-dye producing shells at Berenice provided a welcome addition to this field, a study which Alexander Dedekind, in the 1890s, termed “Pourprologie”.
Before examining the Berenice shells and their context a brief survey will be made of the world-wide usage of shell purple-dye, its Mediterranean origin and distribution, the basic method of production and the contemporary Mediterranean history of the Berenice finds.
Purple-dye is obtained from the hypobranchial gland found in the mantle cavity of living Murex and Thais (or related Purpura and Nucella) marine snails. The purpose of this gland is unclear, though it may be the reason such shells are avoided as food by marine life (and are thus not a useful fish bait). The dye might also be ejected by the mollusc as a defence mechanism, much like the black ink of the octopus or squid.