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September 2016
MODERN MINING
39
EXPLORATION AND
GEOSCIENCE
feature
most of his working career (apart from a stint
in Venezuela) in Africa. He joined Randgold
in 2004 after having worked for a number of
juniors in West Africa. He spends about half of
the year visiting Randgold’s sites in Africa.
Holliday makes the point that in recent years
the annual rate of significant new gold discov-
eries has plummeted down into probably single
figures. “The harsh reality is that the industry
is not replacing what it’s mining. As we speak,
and assuming no further discoveries, the world
only has about 11 years’ worth of gold reserves
at present rates of gold production. The aver-
age grade of new deposits has also halved
in recent years – from around 2 g/t to 1 g/t.
Despite all this, gold exploration budgets have
been slashed around the globe. The gold min-
ing industry will not have a future unless these
trends are reversed.”
The truism that there are no short cuts when
it comes to exploration is demonstrated by the
fact that Randgold has worked on around 1 500
targets over the past 20 or so years – with these
delivering just a handful of deposits deemed
worthy enough to be developed into mines.
It should be stressed though that Randgold
sets the bar high when it comes to evaluating
orebodies. “What we regard as an economic
deposit is one with at least 3 Moz of mineable
gold with a minimum IRR of 20 % at a long-
term gold price of US$1 000/oz,” says Holliday.
“Obviously, viable mines can be developed
from much smaller orebodies but this is not the
space we’re in – we’re focused only on world-
class deposits.”
Currently Randgold’s exploration effort –
which targets the greenstone belts of West and
Central Africa – consumes around US$50 mil-
lion a year and is carried out by approximately
80 graduate geologists, most of them drawn
from the countries in which Randgold operates.
“We don’t have many expatriate geologists,”
says Holliday. “Given the wealth of local talent
available in Africa, we don’t see any need for
them. Many of our geologists have been with
us for many years and some have migrated into
positions of senior management at our mines.”
Detailing Randgold’s current explora-
tion activities, Holliday says expenditure
is divided evenly between greenfields and
brownfields programmes. “In terms of green-
fields exploration, our priority areas in West
Africa are the MTZ (Main Transcurrent Shear
Zone) in Senegal, the Senegal-Mali Shear in
Mali, and the Boundiali and Senefou belts in
Cote d’Ivôire, while in the north-eastern DRC
– where our Kibali mine is located – we are
concentrating on the 35 km-long KZ structure,
A helicopter-borne Versatile
Time Domain Electromag-
netic (VTEM) airborne
survey underway in August
this year over the Ngayu
greenstone belt in the north-
eastern DRC.
which is a terrain boundary hosting multiple
plunging orebodies. The total portfolio contains
137 targets, all of them at varying levels in the
resource triangle model which we use to guide
our exploration and development plans.”
Elaborating on the resource triangle,
Holliday says that Randgold’s generative work
ensures a constant supply of targets to the
base of the triangle. “We apply a set of filters
at progressive levels within the triangle which
allows us to promote quality targets and reject
inferior ones,” he explains. “At any one time,
most of the projects will be in the lower part of
the triangle with only a small number making
it through to the top. If we look at the current
triangle, of the 137 projects, 64 are classified as