Mining Tanzanite

Its single source and limited supply makes Tanzanite at least one thousand times rarer than diamonds.

The world's only Tanzanite-producing area is located near Mount Kilimanjaro in Tanzania, Africa. Only two kilometres wide and four kilometres long, it is split into four sections, named ‘Blocks A to D’.

TanzaniteOne holds the license to mine the largest of these four mining blocks - Block C. The remaining blocks on either side are mostly mined by local artisanal miners. TanzaniteOne uses sophisticated hard rock mining techniques to mine Block C at down-shaft depths of up to 900 metres. World-class infrastructure has been put in place to secure the shafts, provide air supply/ ventilation, watering and dewatering.

Our workers participate in collective wage and condition bargaining and adhere to strict safety policies/ procedures. A focus on safety at the mine site has seen our Lost Time Injuries drop below those of the Diamond Industry. We are proud of this statistic... keeping our people safe is our number one concern.

Geological testing has shown that Tanzanite layers exist down to 2000 meters, which at the current rate of mining would see another 30 years left in the measured deposit. As mining levels drop deeper, increasingly sophisticated infrastructure will be required to access the gemstone.

TanzaniteOne is very proud of its safety initiatives, mining techniques, dedicated workforce, and environmental stewardship.

Mining Statistics

In 2012 The Company achieved a record volume production of tanzanite in 2012, with 2,699,283 carats of tanzanite produced from processing 33,287 tonnes of ore.

Production Statistics

  Unit FY2010 FY2009 FY2008 FY2007 FY2006 FY2005
On Mine cash costs $/carat 3.69 3.63 3.60 3.72 2.90 1.41
Development meters 2504 2519 3877 3935 4671 3700
Plant feed tonnes 37 092 38 154 42 318 25 367 15 896 20 931
Grade c/tonne 59 50 52 67 77 70
Tanzanite Production carats 2 203 818 1 915 440 2 203 162 1 700 134 1 230 600 1 460 075

*On mine cash costs include operating costs, mine administration costs and royalty charges incurred at the mine



Processing and sorting takes place on-site within purpose-built facilities. The ore treatment plant, which includes a Dense Media Separator (DMS), has a current capacity of approximately 10,000 tonnes per month on a single shift. The DMS concentrate passes through a fully automated optical sorting system, where the 'super concentrate' is hand sorted and graded. Rough Tanzanite is sorted both manually and using a fully automated optical sorting/ primary grading system - a world first in the coloured gemstone industry.