Geochemistry studies the formation, development and distribution of chemical elements on earth that are contained in rock-forming minerals and the products obtained from them, as well as in living things, water and the atmosphere.
Determine the abundance of elements in nature, since this information is essential for the development of hypotheses about the origin and structure of our planet and the universe charge, factors that determine their abundance in rocks.
As for distribution, one can only have direct clues about the composition of the earth's crust and indirect clues about the mantle and core. The current knowledge about the geochemical nature of the crust comes from the analysis of geophysical data and rocks. According to these analyzes, oxygen is the main element of the crust with 47% by weight and 94% by volume; second place is occupied by silicon with 28% by weight, but less than 1% by volume.
In addition, metals, when their average grade is concentrated, are a mineral deposit of economic importance; For example, iron and aluminum, which are the most common, need to be concentrated four to five times, copper 80, platinum 600, silver 1250, gold almost 4000, and tungsten and mercury, which are the rarest, need to be concentrated more than 10,000 times with economic Performance to be exploitable.
Extraction
Until about two decades ago, exploration was limited to easily detectable exposed mineralized bodies. Today, however, exploration leads to deposits that are not exposed on the surface and are therefore difficult to locate.
In this new type of indirect exploration, various methods of detecting hidden mineralized objects have been developed; one of them is a geochemical survey based on the established principles of geochemical cycles and distribution of elements.
Geochemical exploration, applied in the mining industry, has three main goals:
- finding metals in various parts near a famous mine, determining their disappearance,
- recurring and new mineral bodies.
- Exploration in the wild Identification and delineation of mineral belts and / or metallic bioregions.
Geochemical environment
Among the basic principles of geochemistry is the recognition of the geochemical environment that develops in the earth's crust, which is grouped as follows:
Geochemical environments at the surface: also called super-primitive, secondary and exogenous, these environments exhibit well-defined physical conditions and features, such as low temperature and pressure, free movement of fluids, abundance of oxygen, water and carbon dioxide, in these environments actions such as weathering, erosion, deposition of vegetation and the soil where it was formed take place.
Dispersion:
This is the formation of mineral deposits with a specific distribution of minerals or associated elements, halos from several centimeters to kilometers in length are formed around the deposits, dispersion can take the following forms:
Primary Dispersion:
Includes all transitions in the formation of how mineralized bodies are formed.
Secondary Dispersion:
Involves the distribution of primary models, by any subsequent process; usually develop below conditions of vasoconstrictor and pressure.
Each sorts rely on the geochemical quality of elements, and this one as well, is subject to the mechanical properties (mobile stage of mineral), viscosity, solution, size, form and density of the grains and also the physic-chemical options of every element.
As a result, geochemical exploration focuses on the determination of the weather of the ore or elements related to the ore that are dispersed, referred to as severally indicator elements and guide elements.
For example, during a deposit of lead-zinc sulfide, the indicator components are lead and zinc, whereas a guide part are mercury.
The various forms of studies which will be performed by developing the sampling elements are:
- Stream sediment geochemistry
- Rock geochemistry
- Water geochemistry
- Soil geochemistry
- Gas geochemistry
- Vegetation geochemistry
The applying of those ways provides a population analysis, involved in applied math type to be graphed on semilogarithmic paper wherever the axis of “Y” has the worth in ppm of the samples and on the axis of “X” will have the percentage of the accumulative frequency.