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
Amethyst gasfield Amethyst gasfield Amethyst is a natural gas field in the Southern North Sea, about east of the Yorkshire coast. Gas lies in a Permian sandstone reservoir around below the seabed. The gasfield is operated by BP. The gasfield was discovered in 1972 and it was named after HMS "Amethyst". Between 1972 and 1985 a number of appraisal wells were drilled. The field development started in 1988 and the first gas was produced in 1991. Originally, the field was owned by BP, Enterprise Oil, British Gas, ARCO, Murphy Oil, Amerada Hess, and FINA. In 1997, BP acquired the interest of Enterprise