Amethyst is a perennial favorite purple mineral that is the February birthstone. People have valued amethyst for thousands of years and it was used for engraved gems by the Egyptians and Romans. Ancient Greeks believed it helped avoid intoxication and the name comes from the Greek “amethystos” or “not drunken”.
Amethyst is a purple variety of quartz (SiO2) and owes its violet color to natural impurities of irradiated iron that replace some of the silicon in the mineral structure. The intensity of the color depends on the amount of iron and the extent of irradiation that occurs due to surrounding minerals.
Like quartz, amethyst is a semi-precious mineral that often forms in crystals and has a hardness of 7 on the Mohs hardness scale, making it ideal for use in jewelry. The intensity of the purple color can vary from one part of the crystal to another. These color variations, known as “color zoning,” often reflect the crystal's geometry and the most intense purple color is often seen near the termination, or end, of the crystals (https://geology.com/gemstones/amethyst/, https://en.wikipedia.org/wiki/Amethyst).
Amethyst is found around the world and forms in igneous (volcanic or magma related), metamorphic (think mountain building) or sedimentary (laid down by water) environments. The large amethyst geodes of Brazil and Uruguay are world renowned, but large amethyst deposits are also found in India, Russia, Korea and the United States. Until the large deposits of Brazil were discovered, amethyst was long considered one of the 5 cardinal stones, the rarest and most valuable gemstones in the world, along with diamonds, rubies, sapphires and emeralds.
Not only is amethyst beautiful, it is believed to be a protective stone that helps relieve stress, soothe irritability, and dispel anger, sadness and grief ( https://www.charmsoflight.com/amethyst-healing-properties). Medieval European soldiers wore amethyst beads for their healing properties and to help them keep cool-headed during stressful times.