Page 119 - Introduction to Mineral Exploration

102 C.J. MOON & M.K.G. WHATELEY

including Michael de Guzman. The gold used land, the next step is to generate targets for
appeared to have been alluvial and had been drilling or other physical examination such
bought from local small scale miners. In this as pitting and trenching or, in mountainous
case, the salting had been difficult to detect as places, by driving adits into the mountainside.
the gold had been added to sample interval that Budgeting and the organization of suitable staff
correlated with alteration and it appeared the are again involved.
fraudsters had used the core logs to determine If the area is remote then suitable topo-
which samples to salt. The only person to face graphical maps may not be available and the
justice was Felderhof who allegedly sold $C83 ground must be surveyed to provide a base map
million in shares before the collapse and went for geological, geochemical, and geophysical
to live in the Cayman Islands, a country with work. Some of the geological investigations
no extradition treaty with Canada. He was may include the mapping and sampling of old
(2004) on trial for insider trading, alleging that mines and the dispatch of samples for assaying.
he sold substantial shares knowing that the Any of this work may locate areas of minera-
Bre-X ownership over Busang was in doubt. lisation which may be recognized by topogra-
The major questions to be addressed in the phical effects, coloring, or wall rock alteration.
wake of the investigation were how such a Different ore minerals may give rise to char-
fraud could be detected and how further frauds acteristic color stains and relic textures in
of this nature could be prevented. There were a weathered rocks and gossans and below these
number of irregular procedures at Busang that supergene enrichment may have occurred. All
should have been detected: these investigations together with pitting and
1 The whole core was assayed and no part was trenching may indicate some promising drill-
kept for a record. ing targets.
2 The gold grains reported were more consist- Geologists should never rush into drilling
ent with an alluvial derivation than from a which is a most expensive undertaking! Very
bedrock source. careful planning is necessary (section 5.2.1) and
3 Pre-feasibility testing indicated a very high drilling programs require meticulous monitor-
recovery by gravity methods – very unusual for ing. Once the drilling is in full swing deciding
epithermal gold deposits. when to stop may be very difficult and various
4 The reported occurrence of near surface possibilities are reviewed in section 5.2.3.
sulfide in a deeply weathered environment. If an exploration program does not resolve
5 The lack of alluvial gold in the stream drain- the potential of some mineralized ground then
ing the Southeast zone. the operating company may sell the option,
6 The wide spaced drilling on the Southeast with or without the data obtained on it, to a
zone (250 by 50 m) that was much larger than new investor. This is often nowadays termed
normal. recycling and it enables the original operator to
The result of the Bre-X fraud has been much recover some of its investment. Such recycling
stricter enforcement of disclosure of ore re- is exemplified by the Mulberry Prospect in
serve calculations methods and the develop- Cornwall (section 5.3). The buying and selling
ment of formal codes such as the JORC code of prospects can be fraught with problems, par-
(see section 10.4). The Bre-X affair also marked ticularly of valuation (section 5.3.1) and also
the end of the exploration boom of the late the possibility of fraud (section 5.4).
1990s and many investors refused to invest
in junior mining stocks, although some made
similar mistakes in the subsequent dotcom 5.6 FURTHER READING
boom.
Basic field techniques are covered in Reedman
(1979), Peters (1987), Chaussier and Morer
5.5 SUMMARY (1987), and Majoribanks (1997). Reviews of
geochemical, geophysical and remote sensing
Following the identification of areas with techniques, covered in Chapters 6–8, as well
possible mineralisation and the acquisition of as some case histories of their integration,