Zambia

Kagem Mine

Click for more information

Categories

Overview

Mine TypeOpen Pit
Commodities
  • Emerald
Mining Method
  • Truck & Shovel / Loader
Production Start... Lock
Mine Life... Lock
ShapshotKagem is the world’s single-largest producing emerald mine.

Owners

SourceSource
CompanyInterestOwnership
Industrial Development Corporation 25 % Indirect
Gemfields Group Ltd. 75 % Indirect
Kagem Mining Ltd. (operator) 100 % Direct
Kagem is 75% owned by Gemfields and 25% owned by the Government of Zambia through the Industrial Development Corporation (IDC).

Contractors

Lock

- subscription is required.

Deposit type

  • Metamorphic hosted

Summary:

Emerald mineralisation in the Kafubu area, including the Kagem deposits, belongs to a group referred to as “schist hosted emeralds”, relating to the interaction of Be-bearing fluids relating to pegmatite dykes or granitic rocks, with Cr -rich mafic and ultramafic schists or weakly metamorphosed ultramafic rocks.

Kagem’s Chama, Libwente, Fibolele and Chibolele deposits form part of a semi-regional scale tight-isoclinal fold system, which trends northeast or east-northeast, ranging in dip from near flat-lying to up to 60° to the southeast or south-southeast, and is locally offset by a series of predominantly north-northwest striking structures.

The suite of PEG dykes and quartz-tourmaline veins that intrude the stratigraphic succession throughout the Kagem deposits occupy a range of trends, both concordant and discordant to the local stratigraphy. At Chama and Chibolele, most discordant dykes strike north or northnorthwest, dipping at around 50° to sub-vertical towards the east or east-northeast. The discordant dykes and veins at Libwente and Fibolele occupy the same trend set, striking north-northwest, but with a steeper, typically sub-vertical dip.

The emerald mineralisation is hosted by the ultramafic TMS unit, with three main styles of mineralisation recognised:
• discordant reaction zone (“RZ”) material adjacent to the PEG and quartz-tourmaline vein contacts;
• concordant RZ material concentrated along the footwall and rarely the hanging wall contacts of the TMS unit; and
• discordant RZ hosted by brittle structures within the TMS unit distal to the PEG and quartz-tourmaline veins.

The RZ is laterally discontinuous and varies in thickness from a few centimetres to more than 2 m.

Mineralisation
Emerald and beryl mineralisation in the Kafubu area, including the Kagem deposits, belongs to a group referred to as ‘schist-hosted emeralds’, in which emeralds occur predominantly in phlogopite or other types of schists. The origin of schist-hosted emerald and beryl deposits is controversial, but is known to require specific geological conditions in which beryllium bearing fluids interact with chromium bearing host rocks. The most established model for emerald and beryl mineralisation in the Kafubu area involves the interaction of Be-bearing fluids relating to pegmatoid dykes or granitic rocks, with Cr-rich mafic and ultramafic schists or unmetamorphosed ultramafic rocks. Other models for schist-hosted emerald and beryl mineralisation propose syn- to post-tectonic growth of beryl in metasomatised ultramafic rock adjacent to Be-bearing PEG during regional metamorphism.

Both the concordant and discordant RZ are laterally discontinuous and vary in thickness from a few centimetres to more than 2 m. All three styles of RZ are mineralogically similar, being composed of phlogopite-biotite-tourmaline aggregates, which are highly soft and friable, providing a protective buffer ideal for the preservation of beryl and emerald crystals. The RZ typically contain beryl mineralisation, of which a variable fraction may be emerald, depending on the chemistry of the TMS. Chemical analyses of phlogopite-rich RZs from emerald and beryl deposits throughout the Kafubu area, indicate that the transformation of ultramafic units into phlogopite schist involves a major influx of K, Al, F, Li and Rb, localised enrichment of Be, dilution of Cr and Ni, and removal of Ca and Si.

Emeralds are a member of the beryl group of minerals which have the chemical formula Be3Al2(SiO3)6 and which show a strong prismatic habit and an imperfect (0001) cleavage perpendicular to the long axis of the crystal (basal pinacoid). They have a hardness of 7.5 to 8.0 and a specific gravity of 2.65 to 2.80. Emerald is the deep green translucent variety of beryl and results from the substitution of Cr, ferrous iron, and in some cases, traces of V, for Al in the crystal lattice.

Kafubu area beryls are typically white to yellowish to bluish white, while the emeralds have a moderate to strong green colouration due to low to moderate levels of Cr2O3 in the range 0.11 wt% to 0.77 wt%. The Kafubu emeralds are characterised by a wide range of trace element contents, typically with moderate levels of Mg and Na, and a moderate to high Fe content. The gemstones have enriched trace element levels, most notably of Cs and Li, but also of K, Rb, Ti, Sc, Mn, Ni, and Zn. Vanadium content is low.

The Kafubu emeralds have relatively high specific gravity (2.69 – 2.77) and refractive index values, especially relatively to emeralds from Colombia. Beryl and emerald mineralisation in the Kafubu area typically forms as subhedral to euhedral hexagonal crystals that often grow in aggregates of multiple gemstones.

Reserves

Lock

- subscription is required.

Mining Methods

Lock

- subscription is required.

Comminution

Crushers and Mills

Lock

- subscription is required.

Processing

Lock

- subscription is required.

Production

Principal mining operations were suspended due to the Covid-19 pandemic from 30 March 2020 to April 2021.
CommodityProductUnits202220212020201920182017
Emerald Mineral k carats  ....  Subscribe  ....  Subscribe  ....  Subscribe20822669
Emerald+Beryl Total k carats  ....  Subscribe  ....  Subscribe  ....  Subscribe42,48141,06221,210

Operational metrics

Metrics202220212020201920182017
Hourly processing rate  ....  Subscribe  ....  Subscribe  ....  Subscribe46 t
Annual processing capacity  ....  Subscribe  ....  Subscribe  ....  Subscribe330 kt
Stripping / waste ratio  ....  Subscribe  ....  Subscribe  ....  Subscribe61 60 75
Ore tonnes mined  ....  Subscribe  ....  Subscribe  ....  Subscribe215.02 kt216.67 kt145.99 kt
Waste  ....  Subscribe  ....  Subscribe  ....  Subscribe13,391 kt13,330 kt10,952 kt
Total tonnes mined  ....  Subscribe  ....  Subscribe  ....  Subscribe13,606 kt13,547 kt11,098 kt
Tonnes processed  ....  Subscribe  ....  Subscribe  ....  Subscribe170,467 t
Hourly processing capacity  ....  Subscribe  ....  Subscribe  ....  Subscribe70 t

Production Costs

CommodityUnits202220212020201920182017
Cash costs Emerald+Beryl USD  ....  Subscribe  ....  Subscribe  ....  Subscribe 0.99 / carat   0.93 / carat   1.62 / carat  

Operating Costs

Currency202220212020201920182017
Total operating costs ($/t mined) USD 3.97  3.5  9.09  3.1  2.82  3.1  
Total operating costs ($/t milled) USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe

Financials

Units202220212020201920182017
Capital expenditures M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe 4.3   11.8   1.5  
Revenue M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe 79   60.3   21.5  
Operating Income M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe 25.9   -27.6   6.9  
After-tax Income M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe 8.4   -18.4   2.8  
EBITDA M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe 18.5   9.8   18.2  
Operating Cash Flow M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe 10.4   8.4   5.3  

Heavy Mobile Equipment

Lock

- subscription is required.

Personnel

Mine Management

Job TitleNameProfileRef. Date
....................... Subscription required ....................... Subscription required Subscription required Sep 27, 2023
....................... Subscription required ....................... Subscription required Subscription required Sep 27, 2023
....................... Subscription required ....................... Subscription required Subscription required Sep 27, 2023
....................... Subscription required ....................... Subscription required Subscription required Sep 27, 2023
....................... Subscription required ....................... Subscription required Subscription required Sep 27, 2023

EmployeesContractorsTotal WorkforceYear
...... Subscription required ...... Subscription required ...... Subscription required 2022
...... Subscription required ...... Subscription required ...... Subscription required 2021
...... Subscription required ...... Subscription required ...... Subscription required 2020
...... Subscription required ...... Subscription required ...... Subscription required 2019
...... Subscription required ...... Subscription required ...... Subscription required 2018
...... Subscription required ...... Subscription required ...... Subscription required 2017
...... Subscription required ...... Subscription required ...... Subscription required 2017

Aerial view:

Lock

- subscription is required.