Underground

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...

Origins: East African Tsavorite

I have spent over 7 years working as a geologist in East Africa, focusing on the exploration and mining of both the blue-violet variety of Zoisite, named Tanzanite, and the green Grossular Garnet, named Tsavorite, respectively. Here I present some of the origins of both present day and past, major and minor sources of the green Grossular Garnet. The locations shown are both exploration areas and mines that I have worked at, and personally seen both mineral and/or gem green Grossular Garnet.

Map of East Africa: The yellow line is the border between Tanzania (to the left) and Kenya (to the right). Mount Kilimanjaro lies to the north of Marangu, and Mount Meru lies to the north of Arusha. The numbers 1-7 show an origin where either exploration and/or mining has taken place for green Grossular Garnet.

Map of East Africa: The yellow line is the border between Tanzania (to the left) and Kenya (to the right). Mount Kilimanjaro lies to the north of Marangu, and Mount Meru lies to the north of Arusha. The numbers 1-7 show an origin where either exploration and/or mining has taken place for green Grossular Garnet.

Here is a summary of the origins 1-7 (number; country/area/owner; description; mining* style):

  • 1 – Tanzania; Merelani (from the Tanzanite Mines); light green tone (mint) garnet, both mineral and gem material; Underground

  • 2 – Tanzania; 16km north east of Merelani; light to medium tone green garnet, only mineral seen; Underground

  • 3 – Tanzania; Shamberai Area; Exploration area, historic underground mining (only origin I never saw any material)

  • 4- Tanzania; Lemshuku Area; light to medium tone, medium saturation green garnet; mineral and gem material; Open Pit

  • 5 – Tanzania; Lemshuku Area (Saul’s Tsavorite Mine); light, medium and dark tone, generally medium saturated green garnet; mineral and gem material; Open Pit

  • 6 – Tanzania; 14km south of Lemshuku Area; medium to dark tone, medium to high saturation green garnet; mineral and gem material; Underground

  • 7 – Kenya; Tsavo (Bridges Tsavorite) – light to medium dark tone, medium to high saturation green garnet; mineral and gem material; Underground

Geologically, what is consistent across the border of the two countries is that all the green garnet is forming in the graphite-rich schists and gneisses of the Neoproterozoic Pan-Africa Orogenic Belt. I have seen green grossular garnet form in two completely different rocks types both containing graphite from the Belt.  The importance of the graphite is significant, as this is the source of the Vanadium, the trace element giving the Grossular Garnet its green color.  And like in all gems, the amount of Vanadium, does vary resulting different tones and saturations.

Is all of the gem green Grossular Garnet, Tsavorite? I am both a geologist and gemologist, but I am guided by what I was taught at the GIA, and that when a gem has a tone of 4 and above (out of 7), then it is Tsavorite Grossular Garnet, irrespective of geographical origin.

*mining includes small scale, unsupported, blasted shafts up to 20m underground, as well large scale, supported, shafts beyond 20m underground.

Green Grossular Garnet and Tsavorite from a small scale, underground mine in Tanzania.

Green Grossular Garnet and Tsavorite from a small scale, underground mine in Tanzania.

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....