Tanzanite, Pride of Tanzania
Modified: April 2011
by Jerry Sisk, GG; Co-Founder, Jewelry Television®
Many adjectives have been used to describe the beauty and elegance of tanzanite, yet its history is still fairly unknown to most. Considered a recent addition to the world of gemstones, tanzanite was brought to light in the mid to late 1960s. The question of who first discovered this rare and beautiful gem is still a matter of debate.
Debates aside, one important fact remains: Tanzanite has made a deep and lasting impression on both the gemstone industry and the general public as a whole, but its road to fame and prominence has been rocky, to say the least.
Its start was impressive. Brought to the attention of Henry B. Platt, then vice president of Tiffany & Co. in New York, the material was named after its country of origin, Tanzania. Having one of the most famous jewelry companies in the world recognize tanzanite's potential was definitely serendipitous. But, as the supply side was not stable, the marketing and promotion of tanzanite eventually came to a halt, causing tanzanite to fall back into obscurity.
The Tanzanian government, recognizing the potential for tanzanite, intervened in 1971 and made an effort to exploit this national resource. The mining and control of tanzanite was subsequently turned over to the State Mining Corporation around 1976. During this period, the mining and production of tanzanite fell off dramatically, causing tanzanite to lose what little market share it had gained.
By the early 1980s, conditions had not improved, so production could be described as irregular at best. Toward the latter part of the '80s, thousands of illegal miners had flooded into Merelani Hills in Northern Tanzania and started exploiting the resources that were present.
It wasn't until 1991 that the Tanzanian government regained control of this area and started issuing licenses to mine. Most of the licenses went directly to native Tanzanians. Interestingly, one of the largest areas within the limited tanzanite-bearing range, Block C, was licensed to a graphite-mining concern that subsequently went out of business.
Geographically, the 6-kilometer-long area where tanzanite has been found is part of a larger geological formation called the Mozambique Belt (recently renamed the East African Orogon). Nestled at the base of Mount Kilimanjaro in the Merelani foothills of Northern Tanzania, the formation was originally divided into four geographic blocks by the government (six with the addition of the extended A and D blocks).
Tanzanite Formation and Mining
The formation of tanzanite is an amazing process that spans across more than 500 million years and requires a very complex series of geological events to occur. In addition, the proper temperature and elements must be present before crystallization of tanzanite can begin. The main coloring agent, vanadium, is required to produce the rich blue-violet colors that are so highly prized.
Interestingly, tanzanite is found in what geologists call "boudins." A boudin is a sausage-shaped formation that is known to contain tanzanite crystals. However, not every boudin will produce tanzanite, and many that do produce contain such low-grade material that it is not useful for jewelry. Unfortunately, these boudins snake around within the earth, making straight, horizontal shafts impractical for mining.
A bi-product of tanzanite mining is another very beautiful gemstone called tsavorite, a form of grossular garnet. As more tsavorite is found, the likelihood of finding jewelry-grade tanzanite lessens. Rhodolite and kyanite are also associated with tanzanite formations.
Most mining is still performed by individuals under what would be considered primitive conditions. Blocks B and D, still actively in production, contain hundreds of small mining operations. Block C, which has been modernized by an international concern, is the only state-of-the-art facility in the entire mining district. Unfortunately, even with high-tech equipment and analysis, the mining of tanzanite is still a difficult task.
Tanzanite itself is actually a variety of the mineral zoisite. While particularly well known for its blue to violet members, greenish to grayish-green material is also prized and goes by the same name. Although pure green tanzanite does exist, it is extremely rare and commands exceptional prices from collectors.
Tanzanite Care and Treatment
Tanzanite looks very different in rough form. Most pieces are the color of Coke-bottle glass when mined and transform into the rich blues to violets after heat treatment. Yet not every piece will heat to the desired color, and some pieces may require multiple heat treatments to complete the process.
Somewhat softer than quartz, tanzanite may be mounted in any form of jewelry. When it is set in rings, additional care should be taken. Tanzanite should never be subjected to extremes in temperature.
Interestingly, some pieces appear more blue than violet. Since tanzanite is a highly pleochroic gem, the color may be manipulated by cutting the stone on one of two axes. Bluer stones are cut on the shorter axis and generally do not provide as high a yield. Consequently, intense blue tanzanite costs more than its violet siblings.
With the advent and growth of television shopping networks, tanzanite has established itself as a major player in the colored-stone market. Sales of tanzanite continue to grow as tens of millions of homes are introduced to this exotic and beautiful gemstone. The proliferation of online shopping has also helped to increase its popularity.
Unfortunately at present, tanzanite is considered a finite resource. Based on historical data and the current mining environment, experts in the field estimate that tanzanite mines have approximately 20 - 30 years left. If no other sources are found, the history of this beautiful and highly prized gemstone may be cut short.
There is still hope that with the emergence of new technologies and additional exploration, other sites may be discovered. If not, then be thankful if you are lucky enough to own one of nature's most beautiful creations.