Ever since Ndugu Jumanne Ngoma stumbled upon shimmering blue crystals in the shadows of Tanzania’s Mount Kilimanjaro, tanzanite has become one of the world’s most sought-after gemstones. No wonder. As anyone who has ever laid eyes on this gem can testify, tanzanite has a take on the blues that can drive even the finest sapphire to kick the nearest dog. And yet, when it was first discovered, Ngoma could hardly give it away:
I found the tanzanite in Merelani, Arusha, in the area called Kiteto at the beginning of January 1967. I was on my way to visit some of my relatives who live in Kiteto, when walking through the bush I saw some crystals of a blue mineral lying on the ground. There were very nice… They were blue, some were transparent… In a few hours I collected about 5kg — they were all very lovely blue crystals.
A friend told me to get on the bus and go to Nairobi… where there was a much bigger gem market than in Arusha. So I borrowed some money for the journey and went to an overseas company who deals in precious stones… and I let them see the 5kg of tanzanite. They didn’t even know what the mineral was. They told me, though, that as soon as they knew, they would let me know. I left them with the 5kg of tanzanite in exchange for a return ticket home, worth $5.… 33 years have gone by and I’m still waiting for their answer! But I kept some samples for myself.
– Ndugu Jumanne Ngoma, relating his discovery of tanzanite to author Valerio Zancanella
Following this discovery, tanzanite quickly became one of the world’s most popular gemstones. Some credit is due to Tiffany & Co., who introduced it to market with a lovely name that pays tribute to the beauty of the land of its birth. Tiffany understood that to call this glamorous gem by its mineral name, blue zoisite, would not do it justice.
Today tanzanite is available in a variety of shapes and sizes. Rarely pure blue, tanzanite almost always displays overtones of violet. In smaller sizes, it tends toward lighter shades of lavender and periwinkle, while in sizes above ten carats, tanzanite can show richer, more intense blue colors.
Tanzanite is trichroic, meaning it shows different colors when viewed in different directions. One direction is blue, another purple, and the other bronze. When found in the ground, the bronze color often dominates. However, with gentle heating (~520°C), one can watch the blue and violet bloom and deepen in the stone. The resulting color is completely stable.
Legend has it that the effect of heat was first discovered when brown zoisite crystals exposed on the surface were caught in a fire set by lightning that swept across the grass-covered Merelani hills. The Masai herders who drive cattle in the area noticed the beautiful blue color and picked the crystals up, becoming the first tanzanite collectors.
Tanzanite is strongly pleochroic, as the above two photos of the same crystal show. Photo: Wimon Manorotkul/Pala International; specimen courtesy of William Larson
Owing their color to traces of the element vanadium, cut stones with more blue than violet tend to be more expensive because the crystals generally form with the blue color axis oriented along the width of the crystal instead of the length. That means that if the cutter chooses to maximize the purity of the blue color, the stone cut from the rough will be smaller and thus cost more per carat. The blue color, however, is so beautiful that the sacrifice is often worth it.
Rarely, stones of a green color are also found. These are particularly valued by collectors.
Proclus in his book of Sacrifice and Magick, saith, That the antient Priests were wont to mix many things together, because they saw that divers Simples had some property of a God in them, but none of them by it self sufficient to resemble him. Wherfore they did attract the hevenly influences by compounding many things into one, whereby it might resemble that One which is above many.J.B. Porta, 1658, Natural Magick
TanzaniteOne's Chief Geologist, Robert Grafen-Greaney, points out the boudins where tanzanite is found.
Photo: Richard W. Hughes
Lying in the shadow of Mount Kilimanjaro, the world’s only commercial tanzanite mines have resulted from massive tectonic activity that created one of the most highly mineralized zones in the world — the Mozambique Orogenic Belt.
Tanzania’s gem deposits are a product of this belt, which cuts a 200–300 km-wide north-south swath through the central and eastern part of the country. Running all the way from Mozambique in the south, to the Sudan and Ethiopia in the north, it is home to many of East Africa’s most important colored gemstone finds.
Rocks in this belt underwent several different cycles of tectonism, as well as extensive metamorphism, plutonism, folding and faulting. The metamorphism produced granulite complexes, which, when combined with major crustal movements, formed a witch’s brew of unusual minerals and color varieties. In the granulitic cauldron, pressure and hot fluids cannibalized minerals for their chromophores — vanadium, chromium, manganese — where they were absorbed by existing minerals. At other times, minerals were simply dissolved and built anew. The result is one of the richest gem belts on the planet.
Tanzanite is recovered from pegmatitic veins that have become so stressed they have broken into smaller pieces known as boudins. Gems are found in small pockets within the boudins.
Map of Tanzania and southern Kenya, showing the major gem localities. The tanzanite mines of Merelani are located just south of Mt. Kilimanjaro. Click on the map for a larger version. Map: R.W. Hughes
Originally tanzanite could easily be collected on the surface, but this scavenger mining quickly gave way to pits and now tunnels, some of which extend hundreds of meters beneath the surface.
Miners work the face in TanzaniteOne's Block C mine. The extraction process begins with brute force, but ends with the utmost care to avoid damaging the gems. Unlike the other blocks, mining conditions at Block C are excellent and the company has a fine safety record. Photo: TanzaniteOne
I couldn't help asking him once what he meant by coming here at all. 'To make money, of course. What do you think?' he said scornfully.Joseph Conrad, Heart of Darkness
While Tanzania's tanzanite mines were discovered by a native Tanzanian, the potential wealth quickly attracted outsiders. These included a variety of characters, both Tanzanian and foreign, who pushed the original discoverer out. Soon the Merelani hills were awash with thousands of fortune seekers and chaos ensued. In 1971, the tanzanite mines were nationalized, but production over the next 20 years was erratic, due to haphazard mining and theft. By 1989, an estimated 30,000 artisanal miners were working in the area.
In 1990, the Tanzanian government curbed artisanal mining and demarcated the area into four blocks: A, B, C and D. Block A was awarded to Kilimanjaro Mines Limited, Blocks B and D to small-scale miners and Block C to Graphtan Limited, a graphite mining company. Graphtan ceased mining activities in 1996 and Afgem acquired the mining licence for Block C. In 2000, Afgem completed a feasibility study for the commercial mining of tanzanite and mine development commenced in 2001. In 2004, the TanzaniteOne Group, a publicly-traded company, acquired Afgem's tanzanite business and assets.
Merelani's tanzanite mines lie within a slender strip of ground, just two km deep by eight km wide. This is Tanzania's most important gem mining area, with as many as 70,000 people supported by those mining, cutting and trading tanzanite in Merelani, Arusha and beyond. 5000 to 6000 miners are said to work at Block D alone, which is the area where the deepest tunnels are found, as the deposit trends down from Blocks A through D.
Sorters cobbing rough at TanzaniteOne's sorting room. Women previously did this job, but after one was found secreting gems in a body cavity and a general search of the room turned up over seven kilos of rough hidden in caches of both the human and man-made kind, the job was given over to men. Today, the overseeing is performed by ex-Gurkha soldiers from Nepal.
Photo: Richard W. Hughes
The TanzaniteOne mine is impressive, to say the least. Indeed, the entire operation exudes class, from the mining conditions underground to the promotional efforts of the Tanzanite Foundation, a non-profit dedicated to promoting tanzanite and assisting the people who mine it. Having observed colored gem mining operations around the world, we must say that the rest of the industry has much to learn from their approach. Does this sound like gushing? We hope so, for they have earned it.
And yet TanzaniteOne faces the dilemma that, no matter how much good work they do, no matter how many schools they fund or roads they build, no matter how much they promote tanzanite as a whole, they will always be regarded with suspicion. The locals understand that, like Joseph Conrad's Kurtz in Heart of Darkness, they have come to this land solely to make money. When the profit is gone, they will leave. Native Tanzanians are different. This is their land, their home. Even if the money is gone, they will remain. They have nowhere else to go.
Kilimanjaro Airport lies some 50 km from Arusha. A further 16 km along a small dirt road brings you to the world's only significant tanzanite deposit. Whirlwinds swirl lazily on the dusty plain as one heads into the Merelani hills, carrying you straight into the blue heart of tanzanite.
Along the way, a sign reveals: "This road has been proudly built, sponsored and maintained by the Tanzanite Foundation."
A Masai next to the sign and road to Merelani. Photo: Tanzanite Foundation
As we passed, a local member of our party declared the billboard an insult. "Look at this road," he snorted. "Dirt! With all the money they are making, why isn't it tarmac [paved]?"
Hmmm… We countered that, while it was unpaved, it did happen to be graded and was as good as any unfinished road in the country. Indeed, in the three weeks we had spent traveling around Tanzania, we had seen far worse.
Then a discussion began on the cost of paving roads. We suggested that such pavement was quite expensive, but that if the Tanzanian government felt a paved road in this place was important, they could simply raise the royalties on TanzaniteOne to pay for it. This brought laughs all around; even the original doubting Thomas had to admit that, if the rent were raised, not a single shilling would make its way to Merelani for road improvement.
The conversation was brought to a rapid halt by an incredible thump. We had just turned off the road maintained by the Tanzanite Foundation and were now on the "regular road" to Merelani. These few kilometers were as rough as anything we had suffered in Tanzania.
The Tanzanite Foundation, a non-profit started by TanzaniteOne, has spent great effort promoting tanzanite around the world, including sponsoring the creation of exceptional pieces designed by some of the world's finest designers. The above ring was designed by Shaun Leane.
Photo: Tanzanite Foundation
Strength is just an accident arising from the weakness of others.Joseph Conrad, Heart of Darkness
Driving towards TanzaniteOne's Block C mines, we inquired as to the possibility of visiting Merelani and the other operations; before we could even finish the sentence, a curt "no" was expelled by the company's driver.
Up on the hill, we took up the question with a higher authority, namely TanzaniteOne's Managing Director, Zane Swanepoel. Brows furrowed and, amidst hushed whispers, the possibility was discussed. The question was not so much that of hiding the dark side, but more one of physical safety. Not just ours, but that of the TanzaniteOne staff who might take us into the lion's den. In the end, discretion ruled. We would have to seek an alternative guide to visit Merelani's blue streets and indigo pits.
Early 20th century map of the Kilimanjaro area. The peak is easily visible from Merelani’s tanzanite mines. From Calvert (1917); courtesy of Pala International.
…and for to seeke out gemmes and some little stones, we strike pits deep within the ground. Thus wee plucke the very heart-strings out of her and all to weire on our finger, one gemme or pretious stone, to fulfill our pleasure and desire. How many hands are worne with digging and delving, that one joint of our finger might shine againe. Surely if there were any devils or infernal spirits beneath, ere this time verily these mines for to feed covetousness and rowt would have brought them up above ground.C. Plinius Secundus, 23–79 AD
The Historie of the World
Several weeks later, our visit to Block D began in humble fashion, with a trip to the mining office to seek permission to tour the mines. Driving through the Merelani streets, it was clear we were a long long way from the mine on the hill. Saloons, pool halls — houses of worship, houses of whoreship. Like mining towns around the world, Merelani was equal parts sin and sincerity.
Guide and permit in hand, we drove to Block D, skirting the razor wire boundary of TanzaniteOne. In numerous places, intruders had cut the fence. It was clear we were riding the border of two entirely different worlds — First and Third — with those on one side not content to stay put.
Not unlike the fence that separates Tijuana from San Diego, razor wire divides the different mining blocks at Merelani. And just like the US-Mexico border, there are repeated signs of breaches as those from the Third World claw their way towards the First.
Photo: Richard W. Hughes