Zambia's amazingly wide spectrum of mineral resources spans a range of metals, particularly copper-cobalt and gold, gemstones, a variety of industrial minerals and potential energy resources - uranium, coal and hydrocarbons. Ranging in size from world-class operating mines to small prospects, the multiplicity and variety of resources demonstrate clearly the opportunities for further exploration and exploitation.
Metal occurrences
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Gold
More than 300 gold occurrences have been recorded but most are
only prospects; largest historical producers are Dunrobin (990kg)
and Matala (225kg) in the Mumbwa area, Jessie (390kg) in the
Rufunsa area, and Sasare (390kg) in eastern Zambia. Dunrobin
was re-opened by Reunion Mining in 1997 as an open-pit, heap-leach
operation and is producing 50kg gold per month. The majority
of the deposits are lode-type bodies associated with the Mwembeshi
Shear Zone and related syntectonic intrusions. Significant gold
mineralization also occurs, variously with copper and uranium,
in major thrust zones near the base of the Katanga succession
Minor palaeo-placer gold has also been reported in the Mporokoso
Group in the Bangweulu Block.
Copper and cobalt
In excess of one billion tonnes of ore (c.2.7% Cu) have been
mined from the mines of the Copperbelt and conservative estimates
suggest that a further two billion tonnes await exploitation.
The copper-cobalt mineralization is stratabound within arenites,
shales and carbonate rocks of the lower-Katanga Mine Series Group.
Copper resources have also been identified in the thrust zones
of north-western Zambia which represent zones of detachment between
Basement and Katanga sequences, and in western and central Zambia
where shearing and intrusion emplacement through the lower Katanga
succession have generated a considerable number of lode, stockwork,
breccia and skarn deposits. Other types of deposit include the
disseminated copper mineralization in the granites and aplites
of the Mkushi area and copper-bearing stratiform sulphides in
the Lusaka area.
Zinc and Lead
Carbonate-hosted Zn-Pb ore has been mined from the Kabwe deposit
in central Zambia where 11Mt of ore averaged close to 25% Zn
and 15% Pb. The stratabound mineralization comprises massive,
breccia and replacement sulphides within carbonate rocks marking
the transition from Lower Roan to Upper Roan. Similar styles
of mineralization at the same stratigraphic position, some copper-rich,
are evident throughout the Kabwe area and northwards to Kapiri
Mposhi. Carbonate-hosted Pb-Zn has also been recorded in Lower
Roan limestones in the Copperbelt and in lower Kundelungu rocks
in western Zambia. Stratabound, probably exhalative, Cu-Zn-Pb
deposits occur in Basement and Muva sequences of south-eastern
Zambia.
Iron
Substantial resources of iron have been identified, occurring
primarily as sedimentary ironstones in the lower-Katanga Mine
Series successions of central and western Zambia. Total resources
of more than 900Mt with an iron content around 50% have been
provisionally estimated, with some individual deposits up to
200Mt in size. Small, high-grade skarn and replacement deposits
are associated with Pan-African felsic and mafic intrusions that
have penetrated the lower Katanga succession in western Zambia,
particularly around the Hook Granite Complex, but such deposits
have rarely been fully evaluated.
Manganese
Occurrences are numerous but mostly small, occurring as tabular,
probably stratiform exhalative, deposits within Basement and
Muva sequences, and as supergene enrichments, either capping
low-grade sedimentary accumulations or concentrated within sub-vertical
fractures of limited vertical extent.
Nickel and Platinum Group Elements
Orthomagmatic nickel occurrences are known in the Basement sequences
east and south of Lusaka and include one near Mpala Gorge which
may be a faulted remnant of ZimbabweÕs Great Dyke. Sediment-hosted
nickel deposits in Mwashia and Mine Series rocks of north-western
Zambia are associated with gabbroic intrusions and often show
evidence of hydrothermal enrichment. Minor platinum group elements
are produced as a by-product of copper-refining on the major
Copperbelt mines.
Tin (-tantalum)
Small quantities of cassiterite have been recovered from complex
quartz-muscovite-feldspar pegmatites of probable Irumide age
in the Choma-Kalomo area in southern Zambia. Columbite-tantalite
has also been extracted in very minor quantities.
Tungsten: Wolframite has been noted in pegmatite of the Choma Tin Belt, and lode-type scheelite-bismuth mineralization is associated with a two-mica granite of early Lufilian age at Unda Unda, 80km east of Lusaka.
Gemstone & Minerals occurrences
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Diamonds
Alluvial diamonds have been reported throughout much of northern,
north-eastern and western Zambia and in many places are accompanied
by indicator minerals. Kimberlite and lamproite intrusions occur
within and near to the western flank of the Luangwa River and
also in southern Zambia but no diamond-bearing diatremes have
yet been discovered.
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Emeralds
Emerald mining |
Other gemstones
Aquamarine and tourmaline are mined in the Lundazi and Nyimba areas of eastern Zambia where they occur in pegmatites that were broadly synchronous with the c.486Ma Sinda batholith. Amethyst is currently being mined in the Mwakambwiko Hills near Lake Kariba where it occurs in veins and stockworks generated during late-Karoo or post-Karoo tectonism.
Zambia boasts a wide range of industrial minerals capable of underpinning the anticipated growth in the mining, manufacturing and agricultural sectors.
Feldspar
In recent years the demand for feldspar has been from local ceramic
producers and also from Kapiri Glass Products Ltd., based at
Kapiri Mposhi. Production has mostly come from two pegmatite
deposits - a 4m-thick body of alkali-feldspar-pegmatite containing
minor muscovite and quartz near Siavonga and a 5m-thick, partially
kaolinized, pegmatite at Shipingu, near Kapiri Mposhi.
Silica Sand
Sands of various specifications occur throughout Zambia but the
only occurrence to have been exploited is the deposit of high-quality
glass sand at Kapiri Mposhi which was the basis for glass manufacture
by Kapiri Glass Products Ltd., until the recent closure of the
company. The sand is an unconsolidated eluvial deposit derived
by the weathering of quartzites of the Muva Supergroup.
Talc
The current small demand for talc within Zambia is met partly
by local production but good quality white talc for the pharmaceutical
industry is imported. Deposits in Zambia have not been extensively
evaluated but range from talc derived during metamorphism of
dolomites near Lusaka to a hydrothermally altered mafic to ultramafic
intrusion, also in the Lusaka area, and talc schist occurring
in the footwall of copper mineralization near Ndola.
Barite
A variety of deposit-types are known, the most significant being
the vein and replacement bodies hosted by red shales and marls
of the Mporokoso Group within the Luongo Fold and Thrust Zone
of the Bangweulu Block. Vein-type mineralization also occurs
within the Irumide Belt and rare occurrences have been reported
associated with the Hook Granite Complex and also hosted by Karoo
sediments within the Mid-Zambezi Rift.
Phosphate
Apatite, the most important potential source of phosphate, occurs
in significant concentrations in syenitic intrusions and carbonatite
bodies. Significant syenite-hosted deposits include the apatite-quartz
bodies of Chilembwe, near Petauke in eastern Zambia, and breccia
and pegmatite bodies in syenite intrusions near the north-eastern
margin of the Hook Granite Complex. Carbonatites in Zambia are
mostly related to Karoo-age rifts and very substantial low-grade
apatite deposits have been noted in two of these - Kaluwe in
the Rufunsa-Feira area and Nkombwa Hill at the northern end of
the Luangwa Rift.
Limestone
Carbonate rocks are a common component of the Katanga Supergroup
and also occur within the Basement Supergroup. Limestone and
dolomite are abundant in the area around Lusaka and these and
other deposits in the Southern, North Western, Northern and Luapula
Provinces have been identified as being suitable for agricultural
use. High-purity, low-MgO limestones are currently being exploited
from the lower Katanga succession near Ndola on the Copperbelt.
Dimension Stone
A very wide variety of potential dimension stones are present
in Zambia but they have rarely been evaluated fully as to their
suitability. They are mostly of igneous origin and include gabbroic
and doleritic rocks of the Basement and Muva terrains in eastern
and central Zambia, granites of the Mpika area in north-eastern
Zambia, and the extensive granitic and charnockitic rocks of
the Chipata area in eastern Zambia. A very attractive pink and
green, sodalite-rich, syenite occurrence has been exploited near
Solwezi, and grey and white marbles are currently being mined
for export on the western outskirts of Lusaka.
Clays
A considerable number of deposits of ball clay and brick clay
are known but they have rarely been subjected to bench tests
and firing tests. Large deposits of ball clay occur at Solwezi
and at Kasanka, 60km north of Serenje, and kaolinite-rich clays
have been recorded at Masuku in southern Zambia and near Shiwa
Ngandu. Brick clays are exploited at an artisanal level throughout
Zambia.
Other Industrial Minerals
These include graphite, gypsum, kyanite and asbestos, with moderate
resources of graphite having been identified at a number of occurrences
in the high-grade metamorphic terrains of eastern Zambia. A major
fluorite deposit has been defined at Sianyolo in the Mid-Zambezi
Valley.
Uranium
Three important types of uranium occurrence have been recorded
in Zambia: in Karoo sandstones; associated with the copper mineralization
of the Copperbelt; and structurally controlled mineralization
in the Basement domes of north-western Zambia. The Karoo occurrences
comprise presumed detrital concentrations, up to 1000ppm U, in
the Escarpment Grit Formation, and fracture-controlled autunite-torbernite-pitchblende
in the same arenitic units of the Mid-Zambezi Rift. Uranium occurrences
associated with the Copperbelt mineralization variously consist
of pitchblende, coffinite, and brannerite, or meta-torbernite
and other secondary minerals concentrated near the base of the
copper mineralization or within the footwall rocks immediately
underlying the orebodies. A total of 120,000kg of U3O8 was produced
from Nkana Mine in the period 1957-1959. Uranium mineralization
in the Basement domes is variously accompanied by copper and
gold and almost invariably occurs in kyanite-bearing schists
which are now known to represent major thrust zones developed
along the
Basement-Katanga contact and propagated up-sequence northwards
and eastwards. The Lumwana Malundwe deposit in the Mwombezhi
Dome, as an example, contains some 4000t of U3O8, in addition to at
least 19.5Mt copper ore at 1.4% Cu and minor gold.
Coal
Zambia possesses substantial coal resources and has been producing
coal continuously since 1967. The bulk of the coal has come from
the Maamba coal mine, an open-cast operation in the southern
part of the country near Lake Kariba. The Maamba deposit and
other known coal occurrences are confined exclusively to the
lower-Karoo Gwembe Formation, within the series of fault-controlled
basins that comprise the Mid-Zambezi Rift Valley. The Maamba
deposit occurs within the Kazinze Basin but coal seams have also
been discovered in the adjacent basins.
Thin coal seams and carbonaceous shales have also been identified
in the lower Karoo (Gwembe Formation) of the Luangwa and Luano-Lukusashi
Valleys and in the eastern part of the Barotse Basin in western
Zambia.
Hydrocarbon
Two exploration programmes by Mobil and Placid Oil between 1986
and 1991 failed to discover oil but, of two boreholes within
the Luangwa Rift Valley, one was terminated before intersecting
the most favourable reservoir horizons. Considerable thicknesses
of littoral and continental sediments underlain by carbonaceous
rocks with oil-generating potential are present within the Karoo-age
graben of both the Luangwa and Mid-Zambezi Valleys.