monazite


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monazite

(mŏn`əzīt), yellow to reddish-brown natural phosphate of the rare earthsrare earths,
in chemistry, oxides of the rare-earth metals. They were once thought to be elements themselves. They are widely distributed in the earth's crust and are fairly abundant, although they were once thought to be very scarce.
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, mainly the ceriumcerium
[from the asteroid Ceres], metallic chemical element; symbol Ce; at. no. 58; at. wt. 140.116; m.p. 799°C;; b.p. 3,426°C;; sp. gr. 6.77 at 25°C;; valence +3 or +4. Cerium is a soft, malleable, ductile, iron-grey metal with hexagonal or cubic crystalline structure.
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 and lanthanumlanthanum
[Gr.,=to lie hidden], metallic chemical element; symbol La; at. no. 57; at. wt. 138.90547; m.p. about 920°C;; b.p. about 3,460°C;; sp. gr. 6.19 at 25°C;; valence +3.
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 metals, usually with some thoriumthorium
[from Thor], radioactive chemical element; symbol Th; at. no. 90; mass number of most stable isotope 232; m.p. about 1,750°C;; b.p. about 4,790°C;; sp. gr. 11.7 at 20°C;; valence +4.

Thorium is a soft, ductile, lustrous, silver-white, radioactive metal.
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. Yttrium, calcium, iron, and silica are frequently present. Monazite sand is the crude natural material and is usually purified from other minerals before entering commerce. Monazite occurs in North Carolina, South Carolina, Idaho, Colorado, Montana, and Florida in the United States, and in Brazil, India, Australia, and South Africa. It is an important source of cerium, thorium, and other rare-earth metals and compounds.

Monazite

 

a mineral; a phosphate of rare earths (mainly of the cerium group) with the chemical formula (Ce, La,…) [PO4]. It often contains various impurities, the most important of which are ThO2 (10 percent and more), UO2 (up to 6.6 percent), ZrO2, CaO, SiO2, and SO3.

Monazite crystallizes in a monoclinic system to form lamellar or sometimes thick tabular crystals, as well as irregular grains and grainy masses. The crystal structure of monazite is characterized by isolated [PO4]3− groups bonded to TR3+ ions in enneadic coordination. It is usually highly radioactive. Its color ranges from yellow or yellow-green to cinnamon and reddish brown. Hardness on the mineralogical scale, 5.0–5.5; density 4,900–5,500 kg/m3, depending on chemical composition.

Monazite deposits are usually associated with granitic pegmatites, less frequently with hydrothermal carbonate veins occurring in alkaline granites and syenites. It is extracted mainly from alluvial deposits in rivers and oceans (for example, in India, Sri Lanka, and Brazil), where it settles during erosion of granite and gneiss containing monazite as an accessory mineral. It is a raw material in the isolation of cerium and thorium.

G. P. BARSANOV

monazite

[′män·ə‚zīt]
(mineralogy)
A yellow or brown rare-earth phosphate monoclinic mineral with appreciable substitution of thorium for rare-earths and silicon for phosphorus; the principal ore of the rare earths and of thorium. Also known as cryptolite.
References in periodicals archive ?
As monazite is an important source of rare earth elements and contains thorium, a naturally occurring radioactive metal, monazite was considered an important national defense resource.
Other minerals that contain them and that are reported in Mexico are: betaphite, monazite, titanite and xenotime.
On which potential economic minerals is 1.76 million tons ,and its estimate zircon 1.58,117 tons, Rutile reserve 71thousand tons ,Ilmenite,1,025,558 tons Magnetite,81.00 thousand tons ,Garnet 222,761tons, Monazite 17,352,tons.
'Nowadays, they sell half of anion latex bedclothes with monazite power and half of them without it.
Gibert, "Solubility measurements of synthetic neodymium monazite as a function of temperature at 2 kbars, and aqueous neodymium speciation in equilibrium with monazite," Geochimica et Cosmochimica Acta, vol.
U-Pb crystallization ages of zircon and monazite were determined by in situ laser ablation inductively coupled plasma-mass spectrometry (LA ICP-MS) at the University of New Brunswick.
(36) This stockpile of monazite was subsequently preserved in Siberia until, ultimately, it was concluded that uranium was easier to use for the production of nuclear arms.
SKN will use its processing technologies for the JV to process monazite concentrate, and Pele will lease a portion of its lands to the JV for construction of the project.
The bulk of the stock is composed of quartz, plagioclase, K-feldspar, muscovite, biotite and accessory minerals (tourmaline, apatite, zircon, monazite, ilmenite, Nb-rich rutile).
Areas with large amounts of thorium-rich monazite sands tip the scales when it comes to background radiation.
The now-defunct Wolff-Alport Chemical Company operated from 1920 until 1954, processing imported monazite sand and extracting rare earth metals.
Request for best offers and proposals in a public auction, in cooperation with Kafr El Sheikh Governorate, for a license for the exploitation, minerals separation, processing and industrial manufacturing of black sand at El Borollos Coast on the Mediterranean including several metals such as eliminate, zircon, rutile, magnetite, garnet & monazite. A comprehensive feasibility study was undertaken by an international specialist firm (Mineral Technologies Australia) has proved that this project is highly economical and attractive according to international mining standards.