Mineral Occurrences of Famous Metals - Essay Example

? Geology Introduction Ores are types of naturally existing rocks having minerals and metal components. It is also known as a metalliferous mineral, which means it is composed of metals and iron components, whose nature and form is largely dependent on the amount of individual components forming it (Green & Basher, 2009 p 124)1. After miners have extracted the ores from the ground, they then refine them using other substances to remain with the valuable elements. Extraction and processing of these iron ores is an expensive venture but it largely depends on mineral concentration and the form it occurs in the ground. In order to establish if a mine is commercially viable, the engineers evaluate if it has substantial mineral and metal deposits whose proceeds will generate income over and above the mining costs. In mineral extraction, there are terms that help us understand this whole refining process. Industrial minerals are stones and other naturally occurring substances that are mined and processed because they have an economic value. This is because they are used to produce other compounds and objects that are used for technological advancements. Protolith is the original rock formation that is passed through a series of solutions to come up with the resultant mineral, the process of passing these rocks through water and other solutions through a chemical reaction is called metasomatism. Gangue is a term that refers to the parts of the ore left after minerals and metals have been extracted. It is the largest contributor to environmental concerns associated with mineral extraction since it forms large debris that is not easily disposed. They also contaminate water meant for commercial and domestic use when it comes into contact with. This is because it has other dangerous minerals which mix with water to form a harmful compound to animal and plant life (Middleton, 2003 p 56)2. Other gases are released to the atmosphere causing air pollution. Occurrences The earth is made up of three components; the air (atmosphere), water (hydrosphere) and land (lithosphere). Minerals form part of the soil underneath our feet. There are numerous geological reactions that happen underground that result in mineral formation and its contents largely depends on the amount of each element taking part in the process. The time taken to form these minerals also ensures huge deposits since some chemical reactions take time to reach full reaction. The time taken and amount of elements forming these minerals and metals determine the quantity and quality of eventual produce. Geologists then determine these considerations before engaging the authorities and locals in preparations for extraction. For instance, to extract commercially viable aluminium from the ground, its composition in the gangue should be at 8.2%, with an acceptable grade of 30%. It is at 5.6% and 50% for iron respectively (Mather, 1967)3. These metals exist in their mineral form in a variety of compounds shown by chemical formulas. Table 1: Mineral occurrences of famous metals Mineral Metal Mineral formula Galena Silver Ag Native gold Gold Au Azurite Malachite Chalcopyrite Copper (exists in three forms) Cu3(CO3)2(OH)2 Cu2CO3(OH)2 CuFeS2 Haematite Magnetite Pyrite Iron(exists in three forms) Fe2O3 Fe3O4 FeS2 Galena Lead PbS Cassiterite Tin SnO3 Cinnabar Mercury HgS Geological distribution These metals exist in the ground as sulphides, sulphites, sulphates, silicates and oxides. The choice of chemicals used in purification stage depends on the form parent metal exists in. Copper exists in three forms (Cu, Cu2 and CuO) and together with iron, are mostly found in carbonate rocks which are formed through a prolonged process of chemical reactions. These metals are also found in sandstones and shales which are sub-crustal rock formations (Press, 2004 p 71)4. Evaluating mineral deposits across the globe is an arduous task since it is difficult to effectively determine the presence of a metal in geographically expansive lands; some not even inhabited by mankind. These metals exist in common forms, what makes the difference is the actual quantity of elements, which eventually determines the metal to be formed. Geologists analyse data got from samples taken from the ground to substantiate if the minerals are commercially viable for extraction. Iron ore is noticed by looking for archaeological evidence available in a given area for instance, the geologists and other technical experts conduct radio carbon dating to determine the levels of radioactivity. These radioactive elements form iron ore, however, the process is thorough to minimize risks associated with wrong deductions. Due to industrial revolution that was experienced in America and Europe, these countries utilized their iron ore resources, and eventually looked to Africa to augment their dwindling resources (Pohl, 2011 p 44)5. However, the continent has vast iron deposits which has not been fully explored and harvested due to political concerns and governance issues hindering global trade in this substance. Copper distribution across the globe is mainly concentrated across North America; however, this cannot be used to measure its abundance as there are many regions still unexplored. Mineral classification Minerals are classified based on their geodynamic environment, tectonic setting, mineral system group and deposit type alongside metal association and the magma. Based on this, we have convergent, divergent, intraplate and hotspot geodynamic environments resulting into various mineral ores and therefore metal elements. Metals of the general composition of gold, silver and mercury are believed to be associated with Meteoric magmatic-hydrothermal as the fluid type in the deposit of carlin in nature. They are mainly found in convergent extensional geodynamic environment set up in the basin free flow with active magma (Strunz & Nickel, 2001)6. Under the convergent extensional environment, there are those that evolve under basinal brines as the fluid and in the deposit type of BHT/Sullivan-type. These include mainly lead, zinc and copper metal association sequence (Gupta & Yan, 2006)7. Under the continental barckarc to which lead, copper and zinc belong, iron (Fe) evolved under seawater as the fluid and in the deposit type called Algoma-type BIF. The mineral system group Magmatic-related hydro thermal has a lot of deposit type responsible for the deposition of various metals. These include :i) Cloncurry-type IOCG which contains the metal association of iron-copper-gold-silver and cobalt as the main components in a fluid referred to as Magmatic-hydrothermal, metamorphic. ii) Olympic Dam-type IOCG which contain iron-copper-gold-uranium-cobalt and molybdenum in Magmatic-hydrothermal, meteoric (Klein, Dutrow & Dana, 2008 p 83)8. Island barckarc rocks include those found within active magmatism and Ortho-magmatic. Some evolve under tholeiitic ultramafic magmas such as Cr while under the same set up evolve under seawater. Strike slip types are formed through deposition and metamorphism. An example is lead under through magmatic hydrothermal (Grande, Augustyn & Weinstein, 2009)9. Generally, such properties result into various ore formation with various metal properties depending on the environment and the processes of formation. It is this aspect that is investigated by engineer to ascertain the quality of the metal to be used in various engineering or general applications. Bibliography Green, D., & Basher, S. (2009). Rocks and minerals. New York: Kingfisher. Middleton, G. V. (2003). Encyclopedia of sediments & sedimentary rocks. Dordrecht: Kluwer Academic Publishers. Press, F. (2004). Understanding earth (4th ed.). New York: W.H. Freeman. Mather, K. F. (1967). Source book in geology, 1900-1950. Cambridge: Harvard University Press. Pohl, W. (2011). Economic geology: principles and practice : metals, minerals, coal and hydrocarbons - introduction to formation and sustainable exploitation of mineral deposits. Chichester, West Sussex: Wiley-Blackwell. Gupta, A., & Yan, D. S. (2006). Mineral processing design and operation an introduction. Amsterdam: Elsevier. Strunz, H., & Nickel, E. H. (2001). Strunz mineralogical tables: chemical-structural mineral classification system (9th ed.). Stuttgart: E. Schweizerbart. Grande, L., Augustyn, A., & Weinstein, J. (2009). Gems and gemstones: timeless natural beauty of the mineral world. Chicago: University of Chicago Press. Klein, C., Dutrow, B., & Dana, J. D. (2008). The 23rd edition of the manual of mineral science: (after James D. Dana) (23rd ed.). Hoboken, N.J.: J. Wiley. Read More