What Is Amethyst?

What is amethyst made of?

Amethyst is a variety of quartz, which is silicon dioxide (SiO2). Pure quartz is colorless or white, with the famous purple color of amethyst coming from trace impurities. The basic crystal structure is identical to other quartz varieties: silicon atoms each bonded to four oxygen atoms in a tetrahedral arrangement, with adjacent tetrahedra sharing oxygen atoms to form a continuous three-dimensional network. The crystal usually forms six-sided prisms ending in hexagonal pyramids. Amethyst forms as the same basic quartz mineral but with the additional purple coloration that requires specific formation conditions.

What gives amethyst its color?

Amethyst's purple color results from a combination of trace iron impurities and natural radiation over geological time. Iron substitutes for some silicon atoms in the quartz crystal structure. Natural radiation (from radioactive elements in surrounding rocks) over millions of years alters the iron atoms' electron configuration, producing color centers that absorb yellow-green light and transmit purple. The intensity of color depends on both iron concentration and radiation dose received. Heating amethyst above about 750°F drives off the color, turning it yellow (creating citrine) or sometimes colorless. Sunlight exposure over long periods can also fade amethyst color.

Where is amethyst found?

Amethyst occurs worldwide but with some sources particularly important. Brazil is the largest producer, with major mines in Rio Grande do Sul and Bahia states. Uruguay produces high-quality deep purple amethyst. Zambia produces dark purple amethyst with red and blue flashes. Other significant sources include Russia (Siberian amethyst was historically prized), Madagascar, India, Bolivia, and the United States. Most large amethyst geodes come from southern Brazil and Uruguay. Smaller amethyst occurrences exist in nearly every country with significant geological diversity. Amethyst forms in volcanic geodes, hydrothermal veins, and some other settings.

How is amethyst used?

Amethyst is used primarily as a gemstone for jewelry. It's the official birthstone for February in modern lists. The deep purple varieties command higher prices than lighter ones. Amethyst is cut into all common gemstone shapes (round, oval, pear, marquise) and sometimes carved into ornamental objects. Large amethyst geodes are sold as decorative items, ranging from small crystal clusters to massive 'cathedral' geodes used in homes and businesses. Amethyst has also been used historically in religious objects, royal regalia, and ceremonial items. Many cultures associate amethyst with spiritual or metaphysical properties.