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The methods used in prospecting for gold

The methods used in prospecting for gold

There are specific methods used in prospecting for any mineral, starting with gold, which is one of the most sought-after precious metals. Before commencing the extraction process, the site and the quantity of gold present are carefully studied during prospecting to ensure the presence of exploitable and profitable gold deposits while minimizing losses resulting from mining activities. The exploration phase, which involves obtaining increasingly detailed data, typically begins with a few specific instances of gold.

The majority of discoveries are based on a geological understanding of deposits. Gold can be extracted from ore at a cost that makes the project economically viable. Even after a mine is opened, exploration activities continue with the aim of increasing resources and reserves and extending the mine’s lifespan.

Investing in Gold Prospecting

According to the global gold market, the total budget allocated for gold prospecting in 2017 was approximately 3.6 billion euros, a significant increase compared to 2016. These budgets were primarily invested in Canada (600.6 million euros), Australia (562.6 million euros), Latin America (936.0 million euros), and Africa (584.8 million euros). These investments are mainly associated with active mining sites or involvement in the final stages of exploration and feasibility studies. Major companies fund almost two-thirds of these investments.

Geological Prospecting Methods

  • Geological prospecting methods for gold exploration primarily rely on field research conducted by geologists to identify signs indicating the presence of mineralization.
  • This involves studying rock outcrops, formations, and rock structures to detect any indications of mineralization.
  • These signs may include the presence of native gold and/or minerals like pyrite, chalcopyrite, or sphalerite, as well as quartz vein systems in suitable contexts or signs of hydrothermal alteration.
  • Geological mapping can also aid in enhancing knowledge of the rocks and structures present in the study area.
  • Upon finding signs of gold beneath the earth’s surface, the initial extraction process involves estimating the quantity, comparing it with the extraction cost, and assessing the probabilities.

Gold Prospecting in Waterways

Gold prospecting can be conducted in alluvial deposits, involving the search for minerals or gold in riverbed sediments. Prospectors use gold pans to concentrate heavy minerals for further detailed laboratory analysis. Generally, this approach is performed parallel to geochemical exploration on stream sediments, involving systematic sampling based on a predetermined grid to obtain a representative sample of catchment areas.

Geochemical Prospecting Methods

Geochemical prospecting methods involve sampling the medium and chemically analyzing it to detect abnormal concentrations that may indicate the presence of mineralization. Geochemical prospecting relies on the measurement of chemical characteristics in rocks, soil, glacial till, stream sediments, water, or plants. As gold is rarely found in isolation, it is usually associated with other elements such as arsenic, selenium, antimony, silver, or tellurium. Samples are typically analyzed to determine the presence of gold through mass spectrometry of total or partial dissolution of the sample.

Prospecting with Plant Roots

Plants, fungi, and bacteria have been successfully used as aids in mineral exploration to locate buried mineral deposits under certain conditions. Many plants, through their extensive root systems and uptake capabilities, take effective samples of various elements available to them, transporting these elements to branches, stems, and leaves, which can be chemically analyzed.

Studies in the United States, Canada, Scandinavia, and the Soviet Union have shown that chemical analysis of fungi in forests provides more accurate results in identifying gold and other mineral deposits than the analysis of basic soil.

Geophysical Prospecting Methods

  • Gold does not have a specific geophysical signature that can be directly detected.Therefore, geophysical methods involve the use of indirect tools and aim to model geological structures or alterations.
  • The methods used are mainly magnetic or electrical.
  • Geophysical methods can be applied in airborne or ground conditions, even using unmanned aerial vehicles (drones) for short-range surveys to some extent.
  • High concentrations of sulfides, such as pyrite, or other magnetic minerals, like magnetite, cause variations that can be detected in the Earth’s magnetic field.
  • Concentrated mineralization or the presence of discontinuities may also cause anomalies in electrical resistivity or induced polarization during electric current application.
  • Gravity measurements also provide valuable information about the subsurface geology and structures that may bear mineralization and alterations.
  • Recent developments in geophysical gold prospecting primarily relate to data processing and quantitative analysis.
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