Primary mineral

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A primary mineral is any mineral formed during the original crystallization of the host igneous primary rock and includes the essential mineral(s) used to classify the rock along with any accessory minerals. [1] In ore deposit geology, hypogene processes occur deep below the Earth's surface, and tend to form deposits of primary minerals, as opposed to supergene processes that occur at or near the surface, and tend to form secondary minerals. [2]

Contents

White veins of gypsum (primary/secondary sulfate mineral) near Gunthorpe in Nottinghamshire, England, UK Gunthorpe formation - diagonal beds - geograph.org.uk - 653299.jpg
White veins of gypsum (primary/secondary sulfate mineral) near Gunthorpe in Nottinghamshire, England, UK

The elemental and mineralogical composition of primary rocks is determined by the chemical composition of the volcanic or magmatic flow from which it is formed. Extrusive rocks (such as basalt, rhyolite, andesite and obsidian) and intrusive rocks (such as granite, granodiorite, gabbro and peridotite) contain primary minerals including quartz, feldspar, plagioclase, muscovite, biotite, amphibole, pyroxene and olivine in varying concentrations. [3] Additionally, primary sulfate minerals occur in igneous rocks. Primary sulfate minerals may occur in veins, these minerals include; hauynite, noselite, barite, anhydrite, gypsum (primary and secondary mineral), celestite, alunite (primary and secondary mineral), creedite, and thaumasite. [4]

Primary minerals can be used to analyze geochemical dispersion halos, and indicator minerals. Furthermore, the most dominant primary minerals in soils are silicate minerals. [5] A variety of silica groups have been discovered, and are controlled by their bonding arrangement, and silica tetrahedron. [5]

Geochemistry

Geochemical dispersion halos

Primary ore deposits contain primary ores that may develop a geochemical dispersion halo known as primary dispersion expressions. [6] "These primary expressions are syndepositional in nature, and thus can occur at or close to the time of ore formation". [6] Primary ore expressions may show alteration of the host rocks. These alterations include; silicification, pyritization, sericitization, chloritization, carbonate alteration, tourmalinization, and greisens. [6]

Indicator minerals

Heavy indicator minerals can lead to a good approximation of primary geology and presence of mineral deposits. Primary indicator minerals can be used to identify gold deposits, kimberlites, and massive sulfide deposits. [7] The indicator minerals are further used to track dispersal trains in streams, which may determine the location of primary ores/minerals, and their source. [7]

Characteristics

Minerals in soils are found in two types; primary and secondary. [5] "A primary mineral has not been altered chemically since its crystallization from a cooling magma." [5] Additionally, a primary mineral is defined as a mineral that is found in soil but not formed in soil, whereas secondary minerals are formed during weathering of

Elbaite (tourmaline) from Minas Gerais, Brazil Elbaite.jpg
Elbaite (tourmaline) from Minas Gerais, Brazil

primary minerals. [8] The latter is further defined by Dr. Broome of North Carolina State: [9] the particle size of primary minerals is primarily larger than 2μm, which includes; silt, sand, and gravel. [5] The most dominant primary minerals in soil are the silicate minerals. Silicate minerals consist of more than 90% of the minerals in the Earth's crust. [5] There are six silica mineral groups, based on bonding arrangement, and silica tetrahedron. [5] The silica groups include: nesosilicates, sorosilicates, cyclosilicates, inosilicates, phyllosilicates, and tectosilicates. [5] Tectosilicates such as quartz, and cristobalite are common in soils. [5] Phyllosilicates are known as the sheet silicates, and include muscovite, biotite, and clay minerals. [5] Cyclosilicates are known as ring silicates, and include tourmaline. [5] Inosilicates are known as single/double chain silicates, and include amphiboles, and pyroxenes. [5] Sorosilicates contain double silica tetrahedra, such as vesuvianite. [5] Nesosilicates have one silica tetrahedra, such as olivine. [5]

The earth's crust and soils are dominated by silicic acid in combination with Na, Al, K, Ca, Fe and O ions. The following elements are components of primary minerals, whereas primary minerals are components of parent rocks. Primary rocks are the source of primary minerals and primary water. For the classical discussions of the origin of primary ores, see the two publications "Ore Deposits" (1903 and 1913). [10] According to W.A. Tarr (1938) the primary mineral deposits are the result of direct magmatic action; he states that the splitting of magmas results in the basic igneous rocks and their accompanying group of accessory minerals formed by the first crystallization in the magma, on the one hand, and in the acidic igneous rocks and a second group of accessory minerals which were formed by deposition from the residual mother liquors. [11]

Beneficiation of primary ores

Leaching of primary sulfate minerals occurs through the process of bioleaching for the separation of primary sulfide ores. [12] Primary ores are also extracted through dense media separation (DMS), which is a technique that involves the removal of gangue through the variation of specific gravity within particles. [12] The dense minerals (high specific gravity) containing primary ores sink, and the lighter gangue minerals float to the surface. [12] DMS plants have been widely used for different mining applications, such as the beneficiation of lithium bearing ores from pegmatites, like the main lithium-bearing mineral known as spodumene. [12] Another method of beneficiation is through magnetic separation. Magnetic separation involves the separation of iron-bearing gangue, such as hematite. [13] Hematite cannot be used in the iron and steel industry without beneficiation. [13] Roasting of primary low grade ores, such as siderite and hematite occurs further forming magnetite. [13] Once the conversion of iron-oxides occurs, magnetic separation may proceed to extract magnetic ores. [13] Additionally, another beneficiation technique used for primary ores is froth flotation. [13] Froth flotation is used after roasting of primary ores, where the magnetite (or other primary ore) is further separated forming a concentrate. [13]

Related Research Articles

<span class="mw-page-title-main">Mineral</span> Crystalline chemical element or compound formed by geologic processes

In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.

<span class="mw-page-title-main">Hornblende</span> Complex inosilicate series of minerals

Hornblende is a complex inosilicate series of minerals. It is not a recognized mineral in its own right, but the name is used as a general or field term, to refer to a dark amphibole. Hornblende minerals are common in igneous and metamorphic rocks.

<span class="mw-page-title-main">Limonite</span> Hydrated iron oxide mineral

Limonite is an iron ore consisting of a mixture of hydrated iron(III) oxide-hydroxides in varying composition. The generic formula is frequently written as FeO(OH)·nH2O, although this is not entirely accurate as the ratio of oxide to hydroxide can vary quite widely. Limonite is one of the three principal iron ores, the others being hematite and magnetite, and has been mined for the production of iron since at least 400 BC.

<span class="mw-page-title-main">Iron ore</span> Ore rich in iron or the element Fe

Iron ores are rocks and minerals from which metallic iron can be economically extracted. The ores are usually rich in iron oxides and vary in color from dark grey, bright yellow, or deep purple to rusty red. The iron is usually found in the form of magnetite (Fe
3O
4, 72.4% Fe), hematite (Fe
2O
3, 69.9% Fe), goethite (FeO(OH), 62.9% Fe), limonite (FeO(OH)·n(H2O), 55% Fe) or siderite (FeCO3, 48.2% Fe).

<span class="mw-page-title-main">Skarn</span> Hard, coarse-grained, hydrothermally altered metamorphic rocks

Skarns or tactites are coarse-grained metamorphic rocks that form by replacement of carbonate-bearing rocks during regional or contact metamorphism and metasomatism. Skarns may form by metamorphic recrystallization of impure carbonate protoliths, bimetasomatic reaction of different lithologies, and infiltration metasomatism by magmatic-hydrothermal fluids. Skarns tend to be rich in calcium-magnesium-iron-manganese-aluminium silicate minerals, which are also referred to as calc-silicate minerals. These minerals form as a result of alteration which occurs when hydrothermal fluids interact with a protolith of either igneous or sedimentary origin. In many cases, skarns are associated with the intrusion of a granitic pluton found in and around faults or shear zones that commonly intrude into a carbonate layer composed of either dolomite or limestone. Skarns can form by regional or contact metamorphism and therefore form in relatively high temperature environments. The hydrothermal fluids associated with the metasomatic processes can originate from a variety of sources; magmatic, metamorphic, meteoric, marine, or even a mix of these. The resulting skarn may consist of a variety of different minerals which are highly dependent on both the original composition of the hydrothermal fluid and the original composition of the protolith.

<span class="mw-page-title-main">Metasomatism</span> Chemical alteration of a rock by hydrothermal and other fluids

Metasomatism is the chemical alteration of a rock by hydrothermal and other fluids. It is traditionally defined as metamorphism which involves a change in the chemical composition, excluding volatile components. It is the replacement of one rock by another of different mineralogical and chemical composition. The minerals which compose the rocks are dissolved and new mineral formations are deposited in their place. Dissolution and deposition occur simultaneously and the rock remains solid.

<span class="mw-page-title-main">Ultramafic rock</span> Type of igneous and meta-igneous rock

Ultramafic rocks are igneous and meta-igneous rocks with a very low silica content, generally >18% MgO, high FeO, low potassium, and are composed of usually greater than 90% mafic minerals. The Earth's mantle is composed of ultramafic rocks. Ultrabasic is a more inclusive term that includes igneous rocks with low silica content that may not be extremely enriched in Fe and Mg, such as carbonatites and ultrapotassic igneous rocks.

<span class="mw-page-title-main">Lamprophyre</span> Ultrapotassic igneous rocks

Lamprophyres are uncommon, small-volume ultrapotassic igneous rocks primarily occurring as dikes, lopoliths, laccoliths, stocks, and small intrusions. They are alkaline silica-undersaturated mafic or ultramafic rocks with high magnesium oxide, >3% potassium oxide, high sodium oxide, and high nickel and chromium.

<span class="mw-page-title-main">Carbonatite</span> Igneous rock with more than 50% carbonate minerals

Carbonatite is a type of intrusive or extrusive igneous rock defined by mineralogic composition consisting of greater than 50% carbonate minerals. Carbonatites may be confused with marble and may require geochemical verification.

<span class="mw-page-title-main">Mineral processing</span> Process of separating commercially valuable minerals from their ores

Mineral processing is the process of separating commercially valuable minerals from their ores in the field of extractive metallurgy. Depending on the processes used in each instance, it is often referred to as ore dressing or ore milling.

<span class="mw-page-title-main">Ore genesis</span> How the various types of mineral deposits form within the Earths crust

Various theories of ore genesis explain how the various types of mineral deposits form within Earth's crust. Ore-genesis theories vary depending on the mineral or commodity examined.

In geology, igneous differentiation, or magmatic differentiation, is an umbrella term for the various processes by which magmas undergo bulk chemical change during the partial melting process, cooling, emplacement, or eruption. The sequence of magmas produced by igneous differentiation is known as a magma series.

<span class="mw-page-title-main">Scientific information from the Mars Exploration Rover mission</span>

NASA's 2003 Mars Exploration Rover Mission has amassed an enormous amount of scientific information related to the Martian geology and atmosphere, as well as providing some astronomical observations from Mars. This article covers information gathered by the Opportunity rover during the initial phase of its mission. Information on science gathered by Spirit can be found mostly in the Spirit rover article.

Kambalda type komatiitic nickel ore deposits are a class of magmatic iron-nickel-copper-platinum-group element ore deposit in which the physical processes of komatiite volcanology serve to deposit, concentrate and enrich a Fe-Ni-Cu-(PGE) sulfide melt within the lava flow environment of an erupting komatiite volcano.

In ore deposit geology, supergene processes or enrichment are those that occur relatively near the surface as opposed to deep hypogene processes. Supergene processes include the predominance of meteoric water circulation (i.e. water derived from precipitation) with concomitant oxidation and chemical weathering. The descending meteoric waters oxidize the primary (hypogene) sulfide ore minerals and redistribute the metallic ore elements. Supergene enrichment occurs at the base of the oxidized portion of an ore deposit. Metals that have been leached from the oxidized ore are carried downward by percolating groundwater, and react with hypogene sulfides at the supergene-hypogene boundary. The reaction produces secondary sulfides with metal contents higher than those of the primary ore. This is particularly noted in copper ore deposits where the copper sulfide minerals chalcocite (Cu2S), covellite (CuS), digenite (Cu18S10), and djurleite (Cu31S16) are deposited by the descending surface waters.

<span class="mw-page-title-main">Mineral redox buffer</span>

In geology, a redox buffer is an assemblage of minerals or compounds that constrains oxygen fugacity as a function of temperature. Knowledge of the redox conditions (or equivalently, oxygen fugacities) at which a rock forms and evolves can be important for interpreting the rock history. Iron, sulfur, and manganese are three of the relatively abundant elements in the Earth's crust that occur in more than one oxidation state. For instance, iron, the fourth most abundant element in the crust, exists as native iron, ferrous iron (Fe2+), and ferric iron (Fe3+). The redox state of a rock affects the relative proportions of the oxidation states of these elements and hence may determine both the minerals present and their compositions. If a rock contains pure minerals that constitute a redox buffer, then the oxygen fugacity of equilibration is defined by one of the curves in the accompanying fugacity-temperature diagram.

This glossary of geology is a list of definitions of terms and concepts relevant to geology, its sub-disciplines, and related fields. For other terms related to the Earth sciences, see Glossary of geography terms.

Magmatic water, also known as juvenile water, is an aqueous phase in equilibrium with minerals that have been dissolved by magma deep within the Earth's crust and is released to the atmosphere during a volcanic eruption. It plays a key role in assessing the crystallization of igneous rocks, particularly silicates, as well as the rheology and evolution of magma chambers. Magma is composed of minerals, crystals and volatiles in varying relative natural abundance. Magmatic differentiation varies significantly based on various factors, most notably the presence of water. An abundance of volatiles within magma chambers decreases viscosity and leads to the formation of minerals bearing halogens, including chloride and hydroxide groups. In addition, the relative abundance of volatiles varies within basaltic, andesitic, and rhyolitic magma chambers, leading to some volcanoes being exceedingly more explosive than others. Magmatic water is practically insoluble in silicate melts but has demonstrated the highest solubility within rhyolitic melts. An abundance of magmatic water has been shown to lead to high-grade deformation, altering the amount of δ18O and δ2H within host rocks.

<span class="mw-page-title-main">Iron-rich sedimentary rocks</span> Sedimentary rocks containing 15 wt.% or more iron

Iron-rich sedimentary rocks are sedimentary rocks which contain 15 wt.% or more iron. However, most sedimentary rocks contain iron in varying degrees. The majority of these rocks were deposited during specific geologic time periods: The Precambrian, the early Paleozoic, and the middle to late Mesozoic. Overall, they make up a very small portion of the total sedimentary record.

Mount Ngualla, often referred to simply as Ngualla, is a collapsed volcano located in the remote south west of Tanzania. It is approximately 200 km north of the Mbeya township.

References

  1. ↑ Ailsa Allaby and Michael Allaby. "primary mineral." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. 1 Oct. 2016.
  2. ↑ Rakovan, John (2003). "A Word to the Wise: Hypogene & Supergene". Rocks & Minerals. 78 (6): 419. doi:10.1080/00357529.2003.9926759. S2CID   128609800.
  3. ↑ "Primary and Secondary Minerals". Lawr.ucdavis.edu. Retrieved 2020-01-30.
  4. ↑ Butler, Bert (December 1, 1919). "Primary (Hypogene) Sulphate Minerals in Ore Deposits". Economic Geology . 14 (8): 581–609. doi:10.2113/gsecongeo.14.8.581 – via GeoscienceWorld.
  5. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Nanzyo, Kanno, Masami, Hitoshi (2018). Inorganic Constituents in Soil. Singapore: Springer Nature Singapore Pte Ltd. pp. 11–14. ISBN   978-981-13-1214-4.{{cite book}}: CS1 maint: multiple names: authors list (link)
  6. 1 2 3 Mcqueen, Kenneth (2005). ORE DEPOSIT TYPES AND THEIR PRIMARY EXPRESSIONS. Bentley, WA: CRC LEME. p. 3. ISBN   9781921039287.
  7. 1 2 Bowell, Cohen, R.J., D.R. (2014). Treatise on Geochemistry (Second Edition) Chapter 13.24 Exploration Geochemistry. Amsterdam ; San Diego, CA, USA.: Elsevier Ltd. p. 635. ISBN   9780080983004.{{cite book}}: CS1 maint: multiple names: authors list (link)
  8. ↑ "Sabine Grunwald - Soil and Water Sciences Department - University of Florida, Institute of Food and Agricultural Sciences - UF/IFAS". Soils.ifas.ufl.edu. 2019-07-31. Retrieved 2020-01-30.
  9. ↑ "Topic 4 Rocks and Minerals". Archived from the original on 2016-10-14. Retrieved 2016-10-20.
  10. ↑ Rickard, T.F.; Ore Deposits: Engineering and Mining Journal, 1903; and Emmons, S.F.; Ore Deposits: A. I. M. E., 1913: pp. 837-846.
  11. ↑ Tarr, W.A.; 1938: Introductory Economic Geology; McGraw-Hill Book Co., Inc., p. 31.
  12. 1 2 3 4 Tadesse, Makuei, Albijanic, Dyer, Bogale, Fidele, Boris, Laurence (2019). "The beneficiation of lithium minerals from hard rock ores: A review". Minerals Engineering. 131: 170–184. doi:10.1016/j.mineng.2018.11.023. S2CID   105940721.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  13. 1 2 3 4 5 6 Yu, Han, Li, Gao, Jianwen, Yuexin, Yanjun, Peng (2017). "Beneficiation of an iron ore fines by magnetization roasting and magnetic separation". International Journal of Mineral Processing. 168: 1. doi:10.1016/j.minpro.2017.02.001 – via Elsevier Science Direct.{{cite journal}}: CS1 maint: multiple names: authors list (link)

Bibliography

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