HD VIDEO - Have you ever actually seen the inside of a Tanzanite mine?

Join me as I take you on a very rare journey into depths of a Tanzanite Mine. The operators and owners of largest and centre-most block in the subdivided tanzanite area, TanzaniteOne/STAMICO on Block C, operate this shaft, Main Shaft. This shaft lies in the centre of tanzanite deposit, and as you see, takes 5 minutes in the skip to get to the bottom of the shaft and to the deepest areas currently being mined. 

Having the opportunity to still be involved in this mining operation after all these years is a blessing. It all started back in December 2002 when documentation was restricted to geological drawings of rock faces and sidewalls. Digital cameras were at an expensive infancy in the US with only talk thereof reaching Africa. And video was restricted to broadcasting agencies! And so no record was kept of truly what was experienced, seen and felt by the people working in the tanzanite mines in East Africa. Fast forward 15 years. Today a personal HD digital video camera is smaller than your hand.

Join me as I attempt to catch up for all those years lost by following me underground doing what excited me from day one back in 2002...

Can Tsavorite be used as an indicator mineral Tanzanite Exploration?

Left to right: 4.8ct Tsavorite, 3.0ct Tsavorite, 2.4ct Tsavorite, 4.5ct Tsavorite and 6.8ct Tanzanite

Left to right: 4.8ct Tsavorite, 3.0ct Tsavorite, 2.4ct Tsavorite, 4.5ct Tsavorite and 6.8ct Tanzanite

Farfetched? Let us see…

Land-based diamond exploration uses the presence of the dense minerals, garnet, ilmenite and olivine minerals as an indicator for the presence of kimberlite, which we know as the source rock for diamonds. Exploration geologists use these minerals because they are hard and dense and they are common minerals found in the kimberlite rock. These minerals are also more common than diamonds.

What do we know about Tsavorite and Tanzanite? Well, Tsavorite is rarer than Tanzanite. And the scale of the mines producing Tanzanite are much larger than the smaller scale Tsavorite mines, and this results in significantly more Tanzanite. The amount of discovered crystals per pocket also favors Tanzanite.

But what about the actual surface area exposure and deposits of Tsavorite versus Tanzanite? From one of my previous blog post Origins: East African Tsavorite (23 April 2017); we can see that known Tsavorite sources between Kenya and Tanzania cover a region way larger than the single Merelani Tanzanite source.

We also know now that Tsavorite and Tanzanite are geologically related as we saw in my previous blog post The Family Tree: Tsavorite and Tanzanite (7 May 2017).

If we use the same proven concept for diamond exploration, we know that Tanzanite is younger and is found in the graphite-rich Tsavorite garnet-bearing host rocks. Tsavorite and green garnet is hard and dense and is preserved near its hardrock source. Can exploration geologists now use the Tsavorite green garnet as an indicator mineral for Tanzanite? I believe so.

Okay, great idea, but what is the point if Tanzanite is only found in one place, you ask? Ask Bruce Bridges from Bridges Exploration about the Tanzanite and blue zoisite he found on his Tsavorite Mines in Kenya sometime…

The Family Tree: Tsavorite & Tanzanite

Green Tsavorite Garnet with Violet Tanzanite (Zoisite) on the outer edge (Photo: B. Olivier). Destruction of the Tsavorite to form Tanzanite.

Green Tsavorite Garnet with Violet Tanzanite (Zoisite) on the outer edge (Photo: B. Olivier). Destruction of the Tsavorite to form Tanzanite.

This year marks the 50th Anniversary of two of the most beautiful gemstones in our industry. The first discovery of green Grossular Garnet and Tanzanite, both took place in 1967 in Tanzania. Tanzanite was named in 1968. Only after the discovery of the green Grossular Garnet in Kenya, was the gemstone named Tsavorite in 1973. Both of these gemstones were named after the locations they were found by Henry Platt, the president of Tiffany & Co.

Most people know this. But how many people know that Tanzanite was created by the recrystallization of Tsavorite? Simply put, Tanzanite was created by the destruction of Tsavorite.

As vanadium is already present in the green grossular garnet (Tsavorite), the equation can be written as:

3 tsavorite + H2O + 5CO2  -  2 tanzanite + 3 quartz + 5 calcite*

which reads: Tsavorite and High Pressure Fluids resulted in Tanzanite & Quartz & Calcite

PhD dissertation of B.Olivier (University of Stellenbosch, RSA, 2006) 

Real Treasures Within The Earth...pt 3

Real Treasures Within The Earth...pt 3

You can only imagine what it must be like waking up 6 am every morning 5 days a week, sometimes 6 days a week, on a colored gemstone mine. Its not like a commercial commodity mine where the goal is to move thousands, sometimes tens of thousands of tonnes of rock a day....