Purple Dyes Made from Shellfish in Antiquity

Two types of precious purple dye were prepared in antiquity from Mediterranean shellfish. Red-purple (biblical argaman, ‘Tyrian purple’) was 6,6′-dibromoindigotin (I, C.I. 75800), made from spiny dye-murex and rock-shells. The nature of the other dye, blue-purple (biblical tekhelet, Greek hyakinthos) has been unclear until recently. The eight proposals advanced during the last 100 years regarding its identity are critically evaluated as to their compliance with the characteristic features historically ascribed to a genuine blue-purple. Also includes correspondence from M Saltzman (JSDC, Vol. 103, Nov 1987, p. 404)