Four organisations with experience in mining, geodata processing
and remote sensing have collaborated in using various spatial analysis
methods, including a Geographical Information System (GIS), to correlate
a wide variety of geographical, geological, geophysical, meteorological
and industrial data of interest to the mining industry. Much of the
information was gathered by remote sensing from aircraft and satellites.
By focusing on three sites in Spain and Germany, the partners have
demonstrated the potential of dedicated digital analysis procedures
for mineral prospecting and for environmental monitoring of activities
of the mining industry.
As known deposits of valuable minerals are
consumed, the mining industry needs to employ increasingly sophisticated
techniques in its search for new reserves. At the same time, mining
companies are becoming more sensitive to environmental issues and
are looking for new tools to help them monitor and reduce the damaging
effects of their operations.
This project arose out of discussions between mining companies and
consultants who recognised the potential for combining prospecting
and monitoring techniques. The project had two main objectives.
First, the partners wanted to find ways to use existing data and
new remote sensing data in the search for hidden mineral deposits.
Second, they wanted to extend the use of remote sensing for the
assessment, surveillance and monitoring of the environmental impact
of mining operations. The main technical challenge was to make the
system sufficiently flexible to accommodate the requirements of
all the potential users.
Until now there has been no systematic use of data for both exploration
and monitoring. Remote sensing, from aircraft and satellites, is
a powerful technique in mineral prospecting which can be adapted
for environmental monitoring. The partners in this project brought
data from remote sensing together with ground measurements in a
GIS, a computer database used to correlate spatial data with an
underlying map of the area.
Three test sites
The project started in November 1992, with research focusing on
three sites: one in central Spain, one in southern Spain and one
in the Erzgebirge of eastern Germany.
• The Pyrite Belt covers more than 8,000 km2 and stretches from
south-western Spain into Portugal. The deposits include copper,
zinc, lead, tin and manganese. It has been mined for more than 4,000
years and several companies are still extracting there. This long
history of exploitation has left a legacy of spoil heaps which cause
serious environmental problems. The Mediterranean climate is ideal
for evaluating the ability of remote sensing and GIS techniques
to detect and monitor contamination from mining activities. The
project concentrated on the central part of the belt in the Huelva
province of Spain, one of the few places of active mining in Europe.
• The Alcudia Anticline is located to the east of the Pyrite Belt,
south of Almadén. It has been intensively mined for lead, zinc and
silver since Roman times. There is no mining there now, but more
than 500 small mines were extracting only a century ago. It is not
a promising area for exploration, but is ideal for using remote
sensing to investigate contamination from old mines in numerous
small places. Roman contamination is especially interesting since
it is already covered by soil and difficult to map.
• The Eastern Erzgebirge, on the border between Germany and the
Czech Republic, is one of the most extensively mined areas in Europe.
Deposits of tin, tungsten, uranium, gold, silver and zinc have been
exploited for more than 1,000 years. The region is characterised
by a high population density and large forests. Environmental damage
caused by mining and related heavy industry is widespread and can
The first step was to collect available information for each of
the three areas and integrate it in the GIS database. For the Erzgebirge,
for example, there were 85 'layers' of information, including 30
sets of remote sensing data. Information included such things as
satellite images and radar maps, aerial photographs, soil geochemistry,
gravity surveys, aeromagnetic data, geological maps, topographical
maps, sources of pollution, meteorological records, and so on. Similar
databases were compiled for the two Spanish areas. New surveys were
undertaken in some areas where the need arose.
Once all these data had been converted into GIS format, researchers
could relate numerous different measurements to each other at each
point on the ground. Complex statistical methods were devised to
restore gaps in irregular and incomplete data sets and to explore
the relationships between different types of data and how they relate
to geological and environmental features of interest. In this very
productive collaboration, the partners used the databases to pursue
15 different lines of inquiry.
The group attempted to identify hidden mineral reserves by using
modelling of geophysical data, extrapolating from surface data and
by simulating the local geology. Possible new target areas have
been identified in the Erzgebirge. Further detailed research along
these lines promises to be fruitful.
The most remarkable results were achieved in environmental monitoring.
By sophisticated analysis of data in the Erzgebirge, the researchers
showed that the loss of forest by acid rain which has taken place
in the last few decades is not directly linked to the presence of
ore mining activities. Damage to the forests, and associated poor
air quality, is rather governed by topographical and climatological
factors and the presence of lignite-fired power stations and associated
Work on a site in the Alcudia Anticline demonstrated the potential
of remote sensing to detect 2,000-year-old mining contamination
through its effect on vegetation, even where the contamination is
now covered by half a metre of new soil. The method, however, needs
to be modified for other sites where soil and vegetation are different.
Another important finding was that ancient lead and silver extraction
does not appear to have had a harmful effect on recent vegetation
now covering the site. The partners believe that using GIS and remote
sensing techniques to identify ancient contamination sites saves
about a third of the time and manpower required by traditional survey
One advantage of the GIS approach is that smaller countries and
companies can have access to data that has historically been the
preserve of large multinational companies with well-resourced exploration
divisions. Small mining companies should now be in a better position
Although this project was designed for the mining industry, especially
for the exploitation of resources and resulting environmental impact,
it is hoped that the principle of correlating many different sets
of information will in future be applied to a wide range of industries
who need to handle specialised data. The mathematical tools developed
in the project should have a wide market, not only in the mining