Amethyst
Amethyst is a common, purple form of the mineral quartz. Fairly
hard, amethyst is a 7 on the Mohs hardness scale which has a range from 1
(softest) to 10 (hardest). Crystals of the mineral often form in clusters,
which is also called druze, and also commonly form in geodes. The purple color
of amethyst is due to the presence of ferric iron (Fe3+) in the quartz crystal
and can range from light to dark. When heated, amethyst will turn brown, into
citrine. Amethyst is considered a semi-precious gemstone that is most commonly used in jewelry and for collecting. Beautiful samples of amethyst can be found in Brazil, Mexico, Uruguay, Russia, India, Sri Lanka, and the United States.