Xenotime: Wikis

This is the first work on this mineral from the Holy Cross Mts. The apparent lack of xenotime and vein pyrite in the tuff-bearing series, compared to the other two series displaying hydrothermal signature pyrite, hematite, nacrite, jarosite , as well as considerable variations of the xenotime overgrowths in size and morphology, and their dominant irregular patchy-zonal microtexture may provide evidence for direct precipitation of this mineral from hydrothermal fluids. Terra Nova 13 5 , American Mineralogist 83, Origin of monazite-xenotime-zircon-fluorapatite assemblages in the peraluminous Melechov granite massif, Czech Republic. Mineralogy and Petrology 94, Zircon behaviour during low-temperature metamorphism. Journal of Petrology 50 4 , Understanding geologic processes with xenotime:

CU Boulder – Electron Microprobe Laboratory – JEOL JXA-8230

Clearly visible in the canyon walls are the light-colored granites, such as the Zoroaster Granite, which are stark against the darker, folded strata of the Vishnu Schist and the other metamorphic rock units of the Granite Gorge Metamorphic Suite1 see lowest purple and green shading in diagram. These are former sedimentary and volcanic strata that have been transformed by heat and pressure, possibly during the intense upheavals when the dry land was formed on Day 3 of Creation Week.

These were originally basalt lava flows several meters to tens of meters thick.

Xenotime is a widespread accessory mineral in lower greenschist to upper amphibolite facies metasedimentary rocks from the Palaeoproterozoic Mount Barren Group, southwestern Australia. Xenotime is closely associated with detrital zircon, commonly forming syntaxial outgrowths, in .

Bring fact-checked results to the top of your browser search. Principles of isotopic dating All absolute isotopic ages are based on radioactive decay , a process whereby a specific atom or isotope is converted into another specific atom or isotope at a constant and known rate. Most elements exist in different atomic forms that are identical in their chemical properties but differ in the number of neutral particles—i. For a single element, these atoms are called isotopes. Because isotopes differ in mass, their relative abundance can be determined if the masses are separated in a mass spectrometer see below Use of mass spectrometers.

Radioactive decay can be observed in the laboratory by either of two means: The particles given off during the decay process are part of a profound fundamental change in the nucleus. To compensate for the loss of mass and energy , the radioactive atom undergoes internal transformation and in most cases simply becomes an atom of a different chemical element. In terms of the numbers of atoms present, it is as if apples changed spontaneously into oranges at a fixed and known rate.

In this analogy , the apples would represent radioactive, or parent, atoms, while the oranges would represent the atoms formed, the so-called daughters. Pursuing this analogy further, one would expect that a new basket of apples would have no oranges but that an older one would have many.

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While zircon has been the most popular mineral for U-Pb dating, other minerals have been employed, including apatite, monazite, titanite, allanite and, most interesting of all, xenotime. Xenotime [ edit ].

NORM results from activities such as burning coal, making and using fertilisers, oil and gas production. Uranium mining exposes those involved to NORM in the uranium orebody. Radon in homes is one occurrence of NORM which may give rise to concern and action to control it, by ventilation. All minerals and raw materials contain radionuclides of natural origin. The most important for the purposes of radiation protection are the radionuclides in the U and Th decay series. For most human activities involving minerals and raw materials, the levels of exposure to these radionuclides are not significantly greater than normal background levels and are not of concern for radiation protection.

However, certain work activities can give rise to significantly enhanced exposures that may need to be controlled by regulation. Material giving rise to these enhanced exposures has become known as naturally occurring radioactive material NORM. NORM is the acronym for Naturally Occurring Radioactive Material, which potentially includes all radioactive elements found in the environment. However, the term is used more specifically for all naturally occurring radioactive materials where human activities have increased the potential for exposure compared with the unaltered situation.

Long-lived radioactive elements such as uranium, thorium and potassium and any of their decay products, such as radium and radon are examples of NORM. These elements have always been present in the Earth’s crust and atmosphere, and are concentrated in some places, such as uranium orebodies which may be mined. However from the perspective of radiation doses to people, such a distinction is completely arbitrary.

In situ U-Pb dating of xenotime by laser ablation (LA)-ICP-MS

Xenotime has a variable habit: It may be prismatic stubby or slender and elongate with dipyramidal terminations, in radial or granular aggregates, or rosettes. A soft mineral Mohs hardness 4. Its lustre , which may be vitreous to resinous, together with its crystal system, may lead to a confusion with zircon ZrSiO4 , that a similar crystal structure and with which xenotime may sometimes occur.

Xenotime has two directions of perfect prismatic cleavage and its fracture is uneven to irregular sometimes splintery.

Zircon (/ ˈ z ɜːr k ɒ n / or / ˈ z ɜːr k ən /) is a mineral belonging to the group of nesosilicates. Its chemical name is zirconium silicate, and its corresponding chemical formula is Zr SiO 4.

Clearly visible in the canyon walls are the light-colored granites, such as the Zoroaster Granite, which are stark against the darker, folded strata of the Vishnu Schist and the other metamorphic rock units of the Granite Gorge Metamorphic Suite1 see lowest purple and green shading in diagram. These are former sedimentary and volcanic strata that have been transformed by heat and pressure, possibly during the intense upheavals when the dry land was formed on Day 3 of Creation Week.

These were originally basalt lava flows several meters to tens of meters thick. In some outcrops pillow structures have been preserved, testimony to the basalt lavas having originally erupted and flowed under water onto the Creation Week ocean floor. Metamorphic rocks are not always easy to date using radio-isotopes. Results obtained usually signify the “date” of the metamorphism, but they may also yield the “age” of the original volcanic or sedimentary rock.

The “age” or “date” is calculated from the amount of the daughter isotope produced by radioactive decay of the parent isotope.

(U-Th)/He Dating of Phosphates: Apatite, Monazite, and Xenotime

Compounds The rare-earth elements form tens of thousands of compounds with all the elements to the right of—and including—the group 7 metals manganese , technetium , and rhenium in the periodic table, plus beryllium and magnesium , which lie on the far left-hand side in group 2. Important compound series and some individual compounds with unique properties or unusual behaviours are described below.

Oxides The largest family of inorganic rare-earth compounds studied to date is the oxides. Most of the discussion will centre on the binary oxides, but ternary and other higher-order oxides will also be briefly reviewed.

2 Microprobe analysis and dating of monazite from the Potsdam 3 Formation, NY: A progressive record of chemical reaction and 63 xenotime, is a promising approach for characterizing past fluid interaction events in 64 sedimentary rocks. Monazite (LREE-phosphate) and xenotime (HREE-phosphate) are.

Volume 69 , September , Pages Review Pegmatites and aplites: Their genetic and applied ore geology Author links open overlay panel Harald G. Dill Show more https: Pegmatites are treated in this study together with aplitic rocks, which are compositionally similar to pegmatites but strikingly different from them by their fine-grained texture.

Rocks of the granitic suite take an intermediate position between the two and, locally, they are transitional into both end-member types, emphasized in the denomination by supplements such as aplite granite or pegmatitic granite. A similar scenario can be reported for syenitic and, less frequently, for granodioritic through dioritic rocks which are found to be associated in time and space with pegmatites and aplites. Pegmatites sensu stricto are found as immigrations into environments different from their birthplace where they were trapped in structures providing the accommodation space necessary for their emplacement and sealed off by impervious roof rocks.

In principle, granites and pegmatites are two sides of the same coin, both are undergoing mobilization and migration; the granite mirrors diffusion and dissemination, the pegmatite reflects trapping and concentration. Fractionation and separation can be recognized in the petroleum as well as in the pegmatite—granite systems. While the mineralogy of pegmatites has been intensively studied and also backed by experimental work, the economic or ore geology of these felsic rocks has not been given adequate attention, particularly when it comes to the classification of the pegmatites.

Xenotime from the Podwiśniówka mine pit, Holy Cross Mountains (South-Central Poland)

It occurs as a common accessory mineral in igneous rocks as primary crystallization products , in metamorphic rocks and as detrital grains in sedimentary rocks. Their average size in granite rocks is about 0. Because of their uranium and thorium content, some zircons undergo metamictization.

Stratigraphic layers within several sedimentary units were sampled to apply the new technique of U–Pb dating of xenotime that sometimes forms as rims on detrital zircon during burial diagenesis; xenotime also can form epitaxial overgrowths on zircon during hydrothermal and metamorphic events.

Papuk encompasses chloritoid-bearing metapelitic and metapsammitic lithologies. Both contain K-white mica, chlorite, chloritoid 10—15 vol. Peak metamorphic conditions during the Alpine chloritoid-forming event reached 3. The chemistry of the chloritoid schists bears the signature of upper continental crustal felsic rocks as potential protoliths, probably the felsic rocks of the nearby Papuk Complex of Slavonian Mts. The evidence presented here for the chloritoid-bearing low-grade metamorphic rocks from the Slavonian Mountains clearly show that the prograde Alpine metamorphic event had a more significant influence on the evolution of the southern part of Tisia Mega-Unit than previously considered.

Tisia Notes Acknowledgments The authors would like to thank Ralf Schuster for his helpful and constructive comments. This research was supported by Croatian Ministry of Science, Education and Sports grant The field and laboratory work were partly covered by bilateral Austria—Croatia and Croatia—Hungary scientific cooperation programs project leaders F. Zorica Petrinec is gratefully acknowledged for her help during preparation of manuscript.

Geochim Cosmochim Acta Rev Mineral Geochem Acta Geol Hung

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It provides precise and accurate chemical composition for elements Be to U at the micron-scale of a large variety of solid materials such as minerals, glasses, alloys, and ceramics. The primary advantage of EMP analysis is the non-destructive and in-situ character of the analysis. All you need is a well-polished, flat sample, such as a regular petrographic thin section or an epoxy mount. EMP is the ideal technique for analyzing chemically zoned crystals, for testing a material’s homogeneity, for sampling delicately intermixed phases, or for identifying and characterizing phases chemistry, size, shape.

As it is an in-situ technique, information on texture and deformation can be preserved.

Dating – Principles of isotopic dating: All absolute isotopic ages are based on radioactive decay, a process whereby a specific atom or isotope is converted into another specific atom or isotope at a constant and known rate. Most elements exist in different atomic forms that are identical in their chemical properties but differ in the number of neutral particles—i.e., neutrons—in the nucleus.

The criticism was blunted, as over time “kenotime” was misread and misprinted “xenotime”. Xenotime has a variable habit: It may be prismatic stubby or slender and elongate with dipyramidal terminations, in radial or granular aggregates, or rosettes. A soft mineral Mohs hardness 4. Its lustre , which may be vitreous to resinous, together with its crystal system, may lead to a confusion with zircon ZrSiO4 , the latter having a similar crystal structure and with which xenotime may sometimes occur.

Xenotime has two directions of perfect prismatic cleavage and its fracture is uneven to irregular sometimes splintery. It is considered brittle and its streak is white. The refractive index of xenotime is 1. Xenotime is dichroic with pink, yellow or yellowish brown seen in the extraordinary ray and brownish yellow, grayish brown or greenish brown seen in the ordinary ray. There is no reaction under ultraviolet light. While xenotime may contain significant amounts of thorium or uranium, the mineral does not undergo metamictization like sphene or zircon would.

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