Kariba Amethyst Mine, Zambia
The Kariba amethyst mine covers an area of 396 hectares, and is located in the southern part of Kalomo district, Zambia (approximately 550 kilometres south- southwest from the Kagem emerald mine). Kariba has produced some of the finest amethyst in the world. Its unparalleled deep purple hue, combined with exceptional lustre, sets the standard for excellence internationally.
Kariba market share has been estimated at over 90% of the amethyst originating from Zambia with annual production reaching as much as 800 tonnes per annum, making it one the largest producers in the world.
Kariba has, over the years, developed a bespoke amethyst grading system that has established its gemstones as premium products.
Gemfields and ZCCM-IH, which each own of 50% of Kariba, recapitalised the operation with US$ 2.5 million in December 2012 so that additional mining and processing equipment could be purchased.
|Location||Southern part of Kalomo district, Zambia|
|Acquisition by Gemfields||May 2004|
|Ownership structure||50% Gemfields, 50% ZCCM-IH (ZCCM-IH is 87% owned by the Government of the Republic of Zambia|
|Mineral Resource||Inferred resource of 325,000 tonnes, with a grade of 37.1 kilograms per tonne No measured of Indicated Mineral Resources are defined|
|Production||800 tonnes per annum|
|Mining method||Open-pit, with a 100 tonne per hour washing plant|
Mineral Resource statement
Amethyst Mineral Resource Statement (dated January 2008)
|Mineral Resources||Tonnage (kt)||Grade (kg/t Amethyst)||Content (kt Amethyst)|
|Total Measured + Indicated||0||0.0.||0.0|
|Subtotal Mineral Resources||325||37.1||12.1|
(1) No Measured or Indicated Mineral Resources are defined at Kariba.
Amethyst mineralisation occurs as fracture fillings in granitic gneisses and marbles. The mineralising fluids started crystallising from the walls of the open cavities inwards. In the Kariba mine area, the host rocks has been exposed to tensile fracturing, creating an extensive network of well-connected cavities. The fractures occurred in weak zones, which were opened during deformation. Earlier fractures also expanded, creating larger openings, and these form the most economically significant mineralised zones. Most of the fracture zones trend northeast to southwest, indicating that the compression was at right angles to the trend.
Three major zones of amethyst mineralisation have been identified within the licence. Two of these are located in the central area and host the mine’s most significant amethyst deposits. These zones run through the Cha Cha, Francis, Curlew, Davidson and Horden prospects. Mining development includes plans to connect the Francis pits (Main Francis, Lower Francis, Top Francis west and Sinamaani pits) and to operate the Basil and Curlew pits.