Glossary of terms
Annual Report 2005     Randgold Resources
AE
Autorisation d’exploration;
Alteration
changes in the composition of a rock, generally chemical or mineralogical, brought about
by weathering or hydrothermal activity;
Andesite
a volcanic rock of intermediate composition;
Archaean
the oldest of the two divisions of the pre-cambrian era, older than 2 500 million years ago;
Argillites
a fine grained sedimentary rock;
Arkose
a sedimentary rock with >25% feldspar content
Arsenopyrite
a sulphide mineral of arsenic and iron (Fe AsS);
Birrimian
geological time era, about 2.1 billion years ago in which a suite of rocks characteristic to
West Africa formed;
Breccia/brecciation
rock type, formed from recrystallised fragments of other rocks;
Boudinage
a structure common in strongly deformed sedimentary and metamorphic rock, in which
an original continuous competent layer or bed between less competent layers has been
stretched, thinned and broken at regular intervals into bodies resembling boudius or
sausages;
Carbon-in-leach (CIL)        a gold recovery process;
Conglomerate
a coarse-grained clastic sedimentary rock, composed of rounded to subangular fragments
greater than 2mm in diameter, set in a matrix of sand or silt (consolidated equivalent of
gravel);
Craton
a part of the earth’s crust that has attained stability and has been little deformed for a long
time;
Cut-off Grade
a g rade level below which the ore is considered to be uneconomic;
Dextral
a structural geology term for the right hand movement of a fault;
Dilution
mixing of ore grade material with non-ore grade/waste material in the mining process;
Diorite
an intrusive igneous rock of intermediate composition;
Dip
inclination of a geological feature/rock from the horizontal;
Dipole
geophysical configuration;
DNGM
Direction Nationale de Géologie et des Mines;
EEP
Exclusive exploration permit;
EP
Exploitation permit;
Feldspar
a group of abundant rock-forming minerals;
Felsic
descriptive of a light-coloured rock containing an abundance of one or all of feldspar,
quartz and felspathoids;
Footwall
the underlying side of an orebody;
GIS
Geographical information system - computer software capable of integrating spatially
related data and querying the various relationships;
Gabbros
an intrusive igneous rock of basic composition;
Geothermal
the internal heat produced by the earth;
Gossans
surface weathering of sulphide minerals creating an iron rich cap;
Greywackes
a medium grained sedimentary rock;
g/t
grammes per metric tonne gold;
Granitoid
geological rock type;
Hangingwall
the overlying side of an orebody;
Hydrothermal
process of injection of heated or hot acqucous-rich solutions into existing rocks;
IP Survey
induced polarisation survey;
Indicated mineral resource that part of a mineral resource for which tonnage, densities, shape, physical characteristics,
grade and mineral content can be estimated with a reasonable level of confidence. It is
based on exploration, sampling and testing information gathered through appropriate
techniques from locations such as outcrops, trenches, pits, workings and drill holes. The
locations are too widely or inappropriately spaced to confirm grade continuity but are
spaced closely enough for geological continuity to be assumed;
Inferred mineral resource   that part of a mineral resource for which tonnage, grade and mineral content can be
estimated with a low level of confidence. It is inferred from geological evidence and
assumed but not verified geological and/or grade continuity. It is based on information
gathered through appropriate techniques from locations such as outcrops, trenches, pits,
workings and drill holes which may be limited or of uncertain quality and reliability;
Intrusion
a rock produced by the emplacement and subsequent solidification of hot magma in pre-
existing rock;
J.O.R.C. Code
the Australian code for reporting mineral resources and ore reserves;
Kriging
an interpolation method that minimises the estimation error in the determination of mineral
resources;