The amethyst is the world famous purple variety of the quartz family (SiO2). Amethyst occurs in crystalline form (usually in geodes) or in massive form (when the conditions for growth are not so conducive). Like quartz, amethyst has a hardness of 7 on the Mohs scale.
The color ranges from dark purple to almost faint lavender. This purple coloring comes about from the presence of iron and aluminium within the amethyst. If amethyst is subjected to heat, it turns yellow (citrine), and if subjected to sunlight, the purple coloring starts to fade away, and it soon resembles white quartz in appearance. Amethyst actually turns yellow at a temperature of 500 Celsius, but reverts back to its purple color if bombarded with x ray particles. All these changes are due to chemical reactions to the iron (ferrous) ions that give amethyst its color.
Amethysts are one of the most common colored variants of the quartz family. It is found in nearly all the places where quartz is found. The deepest amethyst colors occur in specimens from Uruguay, Siberia and certain areas in the USA, such as in Colorado, and Georgia.
Much of the amethysts sold in shops come from Brazil, in particular the Minas Gerais region. The Brandenberg region of South Africa is reputed to produce some stunning deep purple double terminated varieties, while the Vera Cruz region of Brazil produces light colored double terminated specimens. These double terminated varieties are both rare and beautiful, and highly sought after by collectors and purveyors of crystals. They also have strong healing qualities.
However, most amethysts are found as small to medium sized crystals growing as lining in the inner walls of geodes. These geodes are often sought by rich people to decorate a space inside their homes. Small pendants can also be fashioned from larger amethyst pieces or masses. The largest geode (called grotto in this case) so far discovered, was found in the region of Santa Cruz in Brazil in 1900, weighing close to ten tons, and with a dimension of at least several meters in all directions with its longest length at 10 meters. It could easily accommodate several people within the chamber at any given time. Most amethyst geodes though, only range from a foot to a meter in width or height, and are often sought to decorate homes.
A peculiarity of amethyst is its internal structure which is described as “stratified”. If you notice, amethysts usually have differing areas of color concentration within caused by the internal strata or lamellae, and it also tends to fracture in a rippled fashion. Although still a quartz crystal in every sense, this peculiarity sets amethyst apart from other quartz crystal types.
