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Zinc, cadmium, lead, tin, gallium, indium, thallium

Zinc, cadmium, lead, tin, gallium, indium, thallium. Zinc (Zn) Universe: 0.3 ppm (by weight)  Sun: 2 ppm (by weight)  Carbonaceous meteorite: 180 ppm  Earth's Crust: 75 ppm  Seawater:    Atlantic surface: 5 x 10 -5 ppm     Atlantic deep: 1 x 10 -4 ppm. Zinc in magmatic processes.

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Zinc, cadmium, lead, tin, gallium, indium, thallium

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  1. Zinc, cadmium, lead, tin,gallium, indium, thallium

  2. Zinc (Zn) Universe: 0.3 ppm (by weight)  Sun: 2 ppm (by weight)  Carbonaceous meteorite: 180 ppm  Earth's Crust: 75 ppm  Seawater:    Atlantic surface: 5 x 10-5 ppm     Atlantic deep: 1 x 10-4 ppm

  3. Zinc in magmatic processes Zinc abundance in different minerals is a function of the zinc concentration in the magmaand the ability of the crystal structure to incorporate thiselement. It is a major constituent of more than 80 minerals,but there are only a few important commercial ores. The principalZn sulphide minerals are sphalerite (cubic ZnS) and wurtzite (hexagonal ZnS). The occurrence of zinc in some rock-forming ferrous ironand magnesium silicates and oxides (magnetite, pyroxenes,amphiboles, micas, spinel (gahnite, franklinite) and staurolite) is far more importantfor the crustal abundance of this element than zinc in ore deposits. Most of the zinc deposits occur as fillingsand replacements formed by low-temperature hydrothermal solutions.

  4. Zinc in magmatic processes There are many substitution in sphalerite structure. The most important is Fe and Cd. The concentration of other elements in sphalerite depends on the temperature: Co, Mn, Fe, In, Ga, Ge, Tl (order in decreasing temperature). The unique zinc deposit is Franklin Furnace inNew Jersey. The ore minerals there are zincite (ZnO), willemite (Zn2SiO4 ) and franklinite (Fe,Zn,Mn)(Fe,Mn)2O4 occurring as grains in calcite and high temperature and high pressure of their origin is suggested.

  5. Zinc in weathering and sedimentary processes The concentration of zinc in weathering solutions is controlledrather by adsorption (on clay minerals, Fe, Mn, AIhydroxides and organic matter) than by solubility of zinc carbonates,hydroxides and phosphates. The Zn content in soilsdepends on the nature of parent rocks, texture, organic matterand pH and ranges from 10 to 300 ppm. Several soil profile studies show that extractable zinc contentgenerally decreases with depth, while total Zn is uniformly distributed throughout the profile. Higher content of zinc is present in soils in the vicinity of depositsand smelters. Addition of phosphate fertilizers and atmosphericdeposition increases zinc concentration in the soils.

  6. Zinc in weathering and sedimentary processes In aqueous solutions it exists as Zn2+ andsomecomplexions. Zn chloride, sulfate and nitrate are readilysoluble in water, whereas Zn oxide, carbonate, phosphate,silicate and sulfide are practically insoluble in water. CommonZnmineralsintheoxidationzone of Znoredepositsare: smithsonite (ZnCO3), hemimorphite (Zn4Si2O7(OH)2•H2O), aurichalcite (Zn,Cu)5(CO3)2(OH)6 and hydrozincite Zn5(CO3)2(OH)6.

  7. Zinc in weathering and sedimentary processes In surface waters zinc occurs mainly bound to suspended matter (clays, AI, Fe, Mn, Si hydrous oxides). High concentrations of zinc are found in sludge. Freshwaters, especiallyrivers, are frequently contaminated by sewage and waste waterand contain considerable zinc levels. Acid mine water canlocally accumulate zinc up to a high concentration. Zinc occurs in the atmosphere mainly as fine particles (<21-1m). Atmospheric zinc results from the production and processing of zinc, non-ferrous smelters, fossil fuel combustion and car emissions.

  8. Zinc in the biosphere Zinc plays an important role as an essential trace metal in all living systems from bacteria to humans. Zinc is found in all human tissues and all body fluids. The metal is essential for growth, development and reproduction in man. Comparedto other elements such as cadmium, mercury, lead, zinc has a low toxicity.

  9. Cadmium (Cd) Universe: 0.002 ppm (by weight)  Sun: 0.006 ppm (by weight)  Carbonaceous meteorite: 0.45 ppm  Earth's Crust: 0.11 ppm  Seawater:    Atlantic surface: 1.1 x 10-6 ppm     Atlantic deep: 3.8 x 10-5 ppm

  10. Cadmium in magmatic processes Cadmium concentration in igneous rocks is generally low (0.07-0.25 ppm). It is a chalcophile element, favoring an associationwith sulfur, and is closely associated with zinc. The bulk ofcadmium in nature is dispersed as isomorphic impurities invarious other minerals, usually sulfide minerals. The principal carrier is in sphalerite. Common Cd-containing minerals are: greenockite, hexagonal CdS, hawleyite, cubic CdS, otavite, trigonal CdCO3. It always substitutes Zn in different minerals (sphalerite, smithsonite, hemimorphite etc.).

  11. Cadmium in weathering and sedimentary processes It is relatively mobile in the surficial environment. Cadmium often forms complexes with natural organic matter. In many natural environments, aqueous cadmium concentrations are controlled primarily by sorption reactions.It to be enriched in shales, oceanic and lacustrine sediments, andphosphorites, and depleted in red shales, sandstones, and limestones.Carbonaceous shales, formed under reducing conditions,tend to contain the most cadmium.In oxidized zones of ore deposits, it is found in smithsonite, hemimorphite, manganese oxides, and hydrous iron oxides. During weathering,cadmium forms complexes withsulfate and chloride in solution.

  12. Lead (Pb) Universe: 0.01 ppm (by weight)  Sun: 0.01 ppm (by weight)  Carbonaceous meteorite: 1.4 ppm  Earth's Crust: 14 ppm  Seawater:    Atlantic surface: 3 x 10-5 ppm     Atlantic deep: 4 x 10-6 ppm

  13. Lead in magmatic processes It is widely distributed throughout the Earth and can be found in all environmental media (air, soil, rocks, sediments,waters). The average crustal abundance of lead is 16 ppm. Inthe Earth's crust, Pb is the most abundant of the heavy elements with atomic number > 60. Lead occurs in rocks as adiscrete mineral, or the major portion of the metal in theEarth's crust replaces K, Sr, Ba and even Ca and Na in themineral lattice of silicate minerals. Among silicates potassiumfeldspars and micas are notable accumulators of Pb, thereforegranitic rocks tend to have higher levels than basaltic ones.

  14. Lead in magmatic processes ItcansubstitutesCainsomephosphates (apatites), carbonates (aragonite). The largestaccumulationsconnecttopost-magmatichydrothermalprocesses. The most importantPb-sulphidemineral is galena (cubic PbS), butitformsmanyPb-bearingsulphosalts (e.g. boulangerite, bournonite, jamesonite). More than 200 other minerals are known.

  15. Lead in weathering and sedimentary processes In the oxidation zone of Pb-bearing ore deposit found many secondary Pb-minerals, the most common are cerussite (orthorhombic PbCO3 ) and anglesite (orthorhombic PbSO4). However, we know many other compounds in this environments, oxides (minium, litarge, plattnerite), phosphates (pyromorfite), arsenates (beudantite, carminite), chromates (crocoite), molybdates (wulfenite), and vanadates (vanadinite). It can concentrates in sedimentary rocks, which contain organic matters.

  16. Lead in weathering and sedimentary processes Lead in surface run-off comes from chemical weathering, municipal and industrial water discharges and largely from atmospheric deposition. The concentration of lead in naturalwaters is much lower than would be expected from the inputsbecause of adsorption of the element onto particulate matter(clay minerals, oxides and hydroxides of aluminum, iron andmanganese). The adsorption decreases with lowering pH ofthe water. Under reducing conditions lead precipitates as highly insoluble sulfide. Lead occurs in atmosphere as fine particulates ( < 1 1-1m), generated mainly by anthropogenic high temperature sources.

  17. Tin (Sn) Universe: 0.004 ppm (by weight)  Sun: 0.009 ppm (by weight)  Carbonaceous meteorite: 1.2 ppm  Earth's Crust: 2.2 ppm  Seawater:    Atlantic surface: 2.3 x 10-6 ppm     Atlantic deep: 5.8 x 10-6 ppm

  18. Tin in magmatic processes The main tin carriers in granitic rocks are hornblende, biotite, muscovite, garnet, ilmenite and magnetite. Common substitution are in complex oxides, as niobates, tantalates (Sn2+Ca2+, Sn4+ Ti4+ or Fe2+) in high temperature processes. Cassiterite (tetragonal SnO2, the most common tin mineral) occurs in pegmatites, high temperature quartz veins and metasomatic deposits (greisensand tin skarns), generally genetically associated withgranitic rocks.Postmagmatic hydrothermal interaction and chemical alterationof granitic rocks produce greisen enriched in tin. It also occurs in a few volcanogenic massive sulfide deposits related to felsic rocks. At relativelylow temperatures the affinity of tin for sulfur increases (e.g. stannite, cylindrite).

  19. Tin in weathering and sedimentary processes Because of the cassiterite chemical stability, it concentrates in clastic sediments. Most tin is produced from secondary alluvial placers, whichwere eroded from cassiterite deposits. Except for alluvial placers, the abundance of tin is very low in the sediments.

  20. Gallium (Ga) Universe: 0.01 ppm (by weight)  Sun: 0.04 ppm (by weight)  Earth's Crust: 18 ppm  Seawater: 3 x 10-5 ppm

  21. Gallium in magmatic processes Concentration of Gain most of the igneous rocks varies between 1-40 ppm. The Al/Ga ratio decreases only slightly from ultramafic to mafic and felsic rocks. Volatile components and fluoride complexing cause the enrichment of Ga in the late stages of magmatic processes. Together with rare alkali elements it is enriched in pegmatites, and sometimes in minerals of greisens and skarns. The chalcophile character is emphasized especially underhydrothermal, sulfur-rich conditions. Gallium is enrichedmainly in sphalerite (up to 0.16%). The gallium concentrationis temperature dependent and typical for mesothermal oreassociations. (1.88% Ga).

  22. Gallium in weathering and sedimentary processes Gallium is dispersed in the oxidation zone of sulfide mineralizations. The average concentration of Ga in shales and the Al/Ga ratio ofthe latter remain similar to igneous rocks. Ga, like AI, isenriched in weathering. It is more mobile and the Al/Ga ratiotends to decrease in residual materials. Coal may be a collector for Ga. The content of Gain bauxites (20-200 ppm) is of economic importance. The concentration of Ga depends on theweathered rock materials. The highest values are reported from bauxites originating from alkali rocks. The carbonate-derived bauxites display average contents around 50 ppm Ga.

  23. Indium (In) Universe: 0.0003 ppm (byweight)  Sun: 0.004 ppm (byweight)  Earth's Crust: 0.049 ppm Seawater: 1 x 10-7 ppm

  24. Indium in magmatic processes Indium is a rare elements, it occurs mostly as a trace constituent of other minerals.Indium minerals are very rare. Indium prefers tin minerals, especially cassiterite,cylindriteand teallite, as well as minerals with tetrahedral covalent bonds,such as sphalerite, chalcopyrite and stannite.Concentrations in silicates are low, frequently in the range of ppb. Significant concentration of In takes place only in the latefluid-rich stages of magmatic processes, notably in tin-rich associations. Indium is enriched during the formation of greisens,skams and high temperature hydrothermal sulfide mineralizations.In addition to tin minerals, dark iron-rich sphalerites are the most common host mineral.

  25. Indium in weathering and sedimentary processes In indium-rich ore deposits, secondary In minerals may be expected to occur in the oxidationzone; however, only the hydroxide dzahlindite has beendescribed so far. Most of the indium is dispersed in mineralsof the oxidation zone. Iron hydroxides have a high sorptioncapacity for the negatively charged ln(OH)4 anion complex whichmight help indium to be enriched like germanium or gallium. In fossil organic matter like coal, the carbonate sedimenst, and shales have very low concentration of In.

  26. Thallium (Tl) Universe: 0.0005 ppm (by weight)  Sun: 0.001 ppm (by weight)  Carbonaceous meteorite: 0.08 ppm  Earth's Crust: 0.6 ppm  Seawater: 1.4 x 10-5 ppm

  27. Thallium in magmatic processes Thallium is both a chalcophile and a lithophile element. Its chalcophile character is expressed in the formation of a numberof independent sulfides, sulfosalts and selenides with As, Sb,Cu, Pb, Fe, Hg, and Ag (e.g. lorándite TlAsS2, vrbaite, hutchinsonite), and in trace amounts in sulfides (galena, sphalerite, pyrite, etc.). These chalcophileminerals are formed by hydrothermal (epithermal stage)or by supergene processes. Thallium shows lithophile character inK-minerals in igneous and metamorphic rocks. It is concentratedin K-minerals because of their similar size.

  28. Thallium in weathering and sedimentary processes Thallium may be easily released during weathering, but because of its large ionic radius it will be fixed by clay mineralsand the oxides of Fe and Mn in the weathering products. It isvery mobile in oxidized conditions, and in the oxidizing zoneof sulfide deposits it is often enriched in jarosite and manganeseoxides. Because of the higher concentrations ofTh in hydrothermalaltered rocks, it can be used as an indicator element forhydrothermal deposits, especially for epithermal gold deposits.

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