Amethyst even if the iron concentration is low. Natural amethyst is dichroic in reddish violet and bluish violet, but when heated, turns yellow-orange, yellow-brown, or dark brownish and may resemble citrine, but loses its dichroism, unlike genuine citrine. When partially heated, amethyst can result in ametrine. Amethyst can fade in tone if overexposed to light sources and can be artificially darkened with adequate irradiation. Amethyst was used as a gemstone by the ancient Egyptians and was largely employed in antiquity for intaglio engraved gems. The largest Ancient Egyptian amethyst mines are located at Wadi el-Hudi and those mines may be the
SS Empire Amethyst at Belfast to allow a crew member to be discharged through illness and a replacement to be taken on board. On reaching Freetown, "Empire Amethyst" sailed for New Orleans. In mid-April 1942, "Empire Amethyst" left New Orleans bound for Freetown carrying a cargo of 12,000 tons of motor spirit. Her intended route took her via the Lesser Antilles and then across the Atlantic to Freetown. "Empire Amethyst" was spotted by the crew of on 12 April 1942. The U-boat captain, Walther Kölle, believed that she was being escorted by and did not attack. At 03:02 hrs "Empire Amethyst" received a