TOURMALINE

OVERVIEW

Tourmaline’s colors have many different causes. It’s generally agreed that traces of iron, and possibly titanium, induce green and blue colors. Manganese produces reds and pinks, and possibly yellows. Some pink and yellow tourmalines might owe their hues to color centers caused by radiation, which can be natural or laboratory-induced.

Tourmalines come in a wide variety of exciting colors. In fact, tourmaline has one of the widest color ranges of any gem species, occurring in various shades of virtually every hue.

Many tourmaline color varieties have inspired their own trade names:

Rubellite is a name for pink, red, purplish red, orangy red, or brownish red tourmaline, although some in the trade argue that the term shouldn’t apply to pink tourmaline.

Indicolite is dark violetish blue, blue, or greenish blue tourmaline.

Paraíba is an intense violetish blue, greenish blue, or blue tourmaline from the state of Paraíba, Brazil.

Chrome tourmaline is intense green. In spite of its name, it’s colored mostly by vanadium, the same element that colors many Brazilian and African emeralds.

Parti-colored tourmaline displays more than one color. One of the most common combinations is green and pink, but many others are possible.

Watermelon tourmaline is pink in the center and green around the outside. Crystals of this material are typically cut in slices to display this special arrangement.

• Mineral: Tourmaline
• Elbaite Na(Li1.5,Al1.5)Al6Si6O18(BO3)3(OH)4
• Dravite NaMg3Al6Si6O18(BO3)3(OH)4
• Liddicoatite Ca(Li2Al)Al6Si6O18(BO3)3(OH)3F
• Chromedravite NaMg3Cr6Si6O18(BO3)3(OH)4
• Color: All colors
• Refractive index: 1.624 to 1.644
• Birefringence: 0.018 to 0.040
• Specific gravity: 3.06 (+0.20, -0.06)
• Mohs Hardness: 7 to 7.5

This October birthstone is most commonly found in Brazil, but it is also mined in Afghanistan, Pakistan, Kenya, Madagascar and Mozambique (among other countries in Africa). California and Maine are historically important producers of fine tourmaline in the United States.

Most of the tourmaline mined in Brazil over the centuries comes from pegmatites in the state of Minas Gerais. These subterranean intrusions of magma are the source of a virtual kaleidoscope of gem minerals. In the late 1980s, however, electric green, blue and violet tourmalines entered the gem market from pegmatites in Brazil’s Paraíba State. Scientists found that the intense colors were caused by trace amounts of copper, which had previously not been recorded as a coloring agent in any other tourmaline. In the early 2000s, Paraíba-type copper-bearing tourmalines were also discovered in Mozambique and Nigeria. Overall, prices for the best Paraíba and Paraíba-type tourmalines easily surpass other tourmalines due to their vivid hues, higher color saturation and greater rarity.

In the United States, both Southern California and Maine host several pegmatite districts. For more than a century, they have sporadically yielded large quantities of tourmaline.

Maine’s first major tourmaline deposit was discovered in 1820 at Mount Mica in Paris, by two young boys exploring the local area. Even today, a quarry at Mount Mica intermittently produces various colors of gem tourmaline. The Dunton mine, near Plumbago Mountain, is the most prolific producer of tourmaline in Maine.

In 1898, California’s first commercial tourmaline mine opened at the Himalaya pegmatite in the Mesa Grande district – famed for the production of fine rubellite. To feed Empress Dowager Cixi’s obsession with the vibrant color, San Diego mines sent 120 tons of gem rubellite to Imperial China between 1902 and 1910. With the death of Cixi in 1908 and the subsequent overthrow of the Qing dynasty, the heyday of tourmaline mining in California ended. Today, only a few mines in San Diego County occasionally produce gem-quality tourmaline.

The tourmaline birthstone is rated 7 to 7.5 on the Mohs scale of hardness and is generally suitable for everyday wear. These colorful gems are usually stable enough to withstand light and most chemicals, but heat can be damaging. This October birthstone is best cleaned with warm, soapy water and a soft brush The use of ultrasonic and steam cleaners is not recommended.

Now that you know a little bit more about the history of these two October birthstones and where they can be found, you just might be inspired to add them to your collection! But before you go shopping for an October birthstone, be sure to review our Opal Buying Guide and our Tourmaline Buying Guide for tips to help you pick a beautiful October birthstone. Both of these birthstones come in a spectacular array of colors sure to please you or your loved one born in October.

Tourmaline is a birthstone for October, along with opal. Tourmaline is also the gem of the eighth anniversary.

Somewhere in Brazil in the 1500s, a Spanish conquistador washed the dirt from a green tourmaline crystal and confused the vibrant gem with emerald. His confusion lived on until scientists recognized tourmaline as a distinct mineral species in the 1800s. The confusion about the stone’s identity is even reflected in its name, which comes from toramalli, which means “mixed gems” in Sinhalese (a language of Sri Lanka). It’s a term Dutch merchants applied to the multicolored, water-worn pebbles that miners found in the gem gravels of Ceylon (now Sri Lanka).

It’s easy to understand why people so easily confuse tourmaline with other gems: Very few gems match tourmaline’s dazzling range of colors. From rich reds to pastel pinks and peach colors, intense emerald greens to vivid yellows and deep blues, the breadth of this gem’s color range is unrivalled. Brazilian discoveries in the 1980s and 1990s heightened tourmaline’s appeal by bringing intense new hues to the marketplace.

People have probably used tourmaline as a gem for centuries, but until the development of modern mineralogy, they identified it as some other stone (ruby, sapphire, emerald, and so forth) based on its coloring.

One of the earliest reports of tourmaline in California was in 1892. In the late 1800s, tourmaline became known as an American gem through the efforts of Tiffany gemologist George F. Kunz. He wrote about the tourmaline deposits of Maine and California, and praised the stones they produced.

In spite of its American roots, tourmaline’s biggest market at the time was in China. Much of the pink and red tourmaline from San Diego County in California was shipped to China because the Chinese Dowager Empress Tz’u Hsi was especially fond of the color. There, craftsmen carved the tourmaline into snuff bottles and other pieces to be set in jewelry. San Diego County’s famed tourmaline mines include the Tourmaline Queen, Tourmaline King, Stewart, Pala Chief, and Himalaya.

The miners became so dependent on Chinese trade that when the Chinese government collapsed in 1912, the US tourmaline trade also collapsed. The Himalaya mine stopped producing large volumes of gemstones. Other mines in San Diego County, like the Stewart Lithia mine at Pala, still produce sporadic supplies of gem-quality tourmaline.

Source of Content : www.gia.edu