Tyrian purple 520 nm, which is green). 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. In his "History of Animals", Aristotle described the shellfish from which Tyrian purple was obtained and the process of extracting the tissue that produced the dye. Pliny the Elder described the production of Tyrian purple in his "Natural History": The most favourable season for taking these [shellfish] is after the rising of the Dog-star, or else before spring; for when they have once discharged their waxy secretion,
HMS Tyrian (R67) and ratings. The ship was armed with four 45-calibre 4.7-inch (120 mm) Mark XII guns in dual-purpose mounts. For anti-aircraft (AA) defence, "Tyrian" had one twin mount for Bofors 40 mm guns and four twin Oerlikon autocannon. She was fitted with two above-water quadruple mounts for torpedoes. Two depth charge rails and four throwers were fitted for which 70 depth charges were provided. Between 1946 and 1951 "Tyrian" was held in reserve at Harwich. Between 1951 and 1952 she was converted to a Type 16 fast anti-submarine frigate, by Harland & Wolff at Liverpool. She was also allocated the new