Gemstone Review – Amethyst Deposits
Amethyst is the most valuable form of quartz, one of the world’s most plentiful minerals. Amethyst is found in many parts of the world, but the characteristics and quality of amethyst varies according to location. For example, amethyst from South America is often found in large sizes, while African amethyst crystals are usually quite small. However, African amethyst can be highly saturated in color, making it popular with collectors.
The bulk of the world’s supply of amethyst comes from South America, particularly Brazil and Uruguay. The most notable sources of amethyst in Brazil come from Minas Gerais, Rio Grande do Sul, Maraba and Bahia. Brazilian amethyst is typically found in geodes; spherical rocks with crystals lining the inside wall. The crystals that are produced in these areas vary in color from pale to medium lilac and rarely reach deep dark-purple of high saturation. The color of the amethyst in these geodes is most highly concentrated in the tips of the crystals.
Amethyst from Uruguay varies in saturation from medium-saturated to deep, highly-saturated purple. Like in Brazil, amethyst crystals in Uruguay are found in geodes. The geodes of Uruguay have a gray or brownish exterior. The larger geodes contain stalactites and other formations on which amethyst druse (a cluster of tiny crystals that line a rock cavity) forms. Each amethyst crystal contains the entire coloration typical of this region.
Important deposits of amethyst are also found in North America. Thunder Bay, Ontario, is one of the main locations for Canadian amethyst mines where the crystals are found as drusy crusts lining the fissures of ancient metamorphic rock. The Canadian mines produce amethyst with unique reddish inclusions of hematite.
The USA has a great diversity of amethyst deposits that can be found in Maine, Pennsylvania, North Carolina, Montana and Colorado. The color range of American amethyst is generally from medium to high in saturation and may include smoky or translucent crystals. Amethyst from Maine and the Carolinas is usually dark, with North Carolina amethyst having a bluish tint unique to that area. Colorado is known for having clusters of amethyst that have formed in cavities within sandstone.
Two of the main sources of amethyst from Mexico are mines located in Vera Cruz and Guerrero. Amethyst from Vera Cruz has a tendency to be lighter in color and is typically clear. The amethyst that comes from Guerrero is typically a deep and highly saturated dark-purple. The crystals typically have a highly saturated base and pale tips.
Among the African countries that contain amethyst deposits are Zambia and Namibia. These typically contain small crystals of saturated color and outstanding clarity. The rough amethyst crystals are usually polished and carved.
Two of Europe’s most notable sites for amethyst are found in Italy and Germany. Italy’s deposits contain amethyst crystals of evenly distributed color. Crystals of pale hue are often large in size and can occur parallel in formation. German amethyst is often pale in color and is sometimes found coupled with other forms of crystal such as agate.
Amethyst deposits can also be found in other countries around the world such as Bolivia, Argentina, Madagascar, India and Sri Lanka.