Rare
metals
The rare metals beryllium, lithium,
tantalum and niobium and alloys made from them have
a wide variety of uses and have become increasingly
important in today's technology driven society. For
example all are used in the aircraft industry and lithium
and niobium also have nuclear applications.
Rare metals in Afghanistan
There are currently a total of
49 recorded occurrences of these metals in the Afghan
mineral occurrence database, all occurring in pegmatitic
rocks. Initial prospecting was completed in the 1960s
and 70s and identified the areas discussed below, but
further exploration will be necessary to prove the
existence of economically significant deposits.
Beryllium
Eight pegmatite fields with beryllium
mineralisation have been identified to date in the
Laghman and Nangarhar provinces. The mineralisation
is typically related to either Oligocene or Early Cretaceous
magmatism, being hosted in the surrounding metasediments.
The most detailed work was conducted at the Darrahe-Pech
deposit, where beryl crystals up to 40 cm across have
been discovered and category C1+C2 resources of 12
000 t of beryl (containing 1 480 t of beryllium oxide)
have been estimated. The beryllium (and lithium) mineralisation
is associated with albitised-microcline and spodumene-albite
pegmatites. Coarse beryl has also been produced at
the Darrahe-Nur deposit.
Lithium
Twelve pegmatite fields with lithium
mineralisation have been identified to date in Laghman
and Nangarhar provinces, but also in Badakhshan and
Uruzgan provinces. Again the mineralisation occurs
in pegmatites hosted in variably aged metasediments,
typically intruded by Oligocene granitoids. The most
thoroughly evaluated area is the Parun pegmatite field
(Nangarhar province), where seven separate mineralised
zones have been recognised. Four pegmatite types have
been recognised in the area, with the spodumene-albite(-
microcline) type being the most economically significant
and typically grading around 1.5% lithium oxide. Only
speculative resources were estimated and the area clearly
deserves more detailed exploration. The same is true
for the Taghawkor prospect in Uruzgan, where five pegmatite
dykes assay between 1.7 and 2.8% lithium oxide.
Tantalum and Niobium
Fourteen pegmatite fields with
tantalum and niobium mineralisation have been identified
to date, with eleven of these also containing beryllium
or lithium mineralisation. The remaining three are
located in Parwan and Badakhshan provinces. The prospect
with the greatest potential is Nilaw in Laghman province.
Here three types of pegmatite cross-cut Early Cretaceous
gabbros and diorites. Individual pegmatites up to 4
km long and 4 m wide have been discovered, containing
beryllium, lithium, tantalum, niobium, cessium, rubidium
and tin. Systematic exploration will be necessary to
determine the economic viability of the prospect.
. . . at the Darrahe-Pech
deposit beryl crystals up to 40cm across have been
discovered . . .
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