Knowledge of the elements associated with mineral deposits is one of the main requirements for geochemical exploration. Awareness of the economic size of deposits, the mineralogical form of the elements, the size of elemental anomalies, etc. are some of the other prerequisites.
The primary goal of geochemical exploration is to locate specific anomalies. The collected data must be statistically analyzed through the use of computers.
Massive sulphide deposits, for example, contain some amounts of arsenic and gold, in addition to copper, lead, etc.
Calorimetry, atomic absorption spectrophotometry, X-ray fluorescence, inductively coupled plasma emission spectrometry, inductively coupled plasma mass spectrometry, etc. are important methods applied in geochemical exploration.
Measurement of density, magnetism, resistivity, speed of sound, etc. provides information on hidden geology. Airborne geophysical surveys are the fastest and cheapest way to provide geology data over larger areas. The cesium vapor magnetometer and the proton magnetometer are some of the most widely used instruments for magnetic studies. Magnetic minerals produce easily detectable anomalies.
Metal sulfides and oxides are denser than the rocks that surround them. The gravity field at the earth’s surface is slightly influenced by density variations in the underlying rocks. This principle is the basis of the gravity method.
Other geophysical methods are radiometric, resistivity, spontaneous polarization, induced polarization, seismic refraction, reflection, and borehole geophysics.
The appearance of outcrops is variable and depends on several factors. Some of the exploration techniques are the location of crops and the detection of old work. A copper deposit in Indonesia was recognized due to its green-tinted top. Similarly, iron deposits were detected in Brazil as they protruded through tropical rain forests.
In addition to topographical anomalies, most outcropping mineral deposits show variations or anomalies in their colors. For example, black and white outcrops indicate the likely presence of manganese and zinc, respectively. Similarly, red blooms generally indicate the presence of mercury. In Western Australia, eroded sulphides overlie gold or base metal deposits.
Aerial photographs provide reliable geological information in areas of clear and perfect exposures. They provide better information even if the outcrop exposure is around 5%.
After identifying mineralized zones and land acquisition, the next steps in the exploration process are generation of drill targets, physical examinations. through pits or trenches. Great care must be taken in planning drilling activities at all stages.
The pit or trench is ideal in regions with little outdoor crop exposure to confirm the origin of bedrock anomalies. Geological mapping is one of the main processes of mining exploration.