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
HMS Amethyst (1799) company with , captured "Agnela". On 30 July "Amethyst" captured the "Ebenezer", and then on 1 August "Amethyst" captured "Juno". In December "Amethyst" participated in the pursuit of a French squadron under Admiral Willaumez. In November 1805 "Amethyst" encountered the brig-sloop off the coast of Madeira. After a series of ambiguous and misinterpreted moves by the other, the two captains mistook each other for enemies and opened fire. Both vessels survived and the two captains proceeded to exchange mutually recriminatory letters. "Amethyst" was among the vessels that shared in the proceeds of the capture, on 25 July 1805, of the