Surface reactions of synthetic, end-member analogues of monazite, xenotime and rhabdophane, and evolution of natural waters

Journal Article · Tue Mar 01 04:00:00 EST 1988 · Geochimica et Cosmochimica Acta; (USA)

DOI:https://doi.org/10.1016/0016-7037(88)90336-5· OSTI ID:5254277

Jonasson, R G ^[1]; Bancroft, G M ^[2]; Boatner, L A ^[3]

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1. McMaster Univ., Hamilton, Ontario (Canada)
2. Univ. of Western Ontario, London (Canada)
3. Oak Ridge National Laboratory, TN (USA)

Recently, evidence has accumulated that certain carbonate and sulfate minerals undergo selective surface ion-exchange reactions with aqueous solutions at low temperatures. Evidence obtained by powder XRD, SIMS and XPS is presented here indicating that synthetic rare earth element (REE) phosphate mineral analogues undergo similar reactions. Hydrous Ho-xenotime reacts with aqueous Nd{sup 3+} over a period of months to produce Nd-rhabdophane. Sm- and Nd-monazite crystals undergo detectable surface exchange reactions within 5 days at 65{degree}C. Ho- and Er-xenotime react similarly. Exchange of Y and Lu in the surface layers of Lu-xenotime is pH dependent, with lower pH favoring replacement. Clearly, such effects are relevant to the debate about REE concentrations and signatures in natural waters, particularly in view of the widespread occurrence of monazite in nature.

• DOE Contract Number: AC05-84OR21400
• OSTI ID: 5254277
• Journal Information: Geochimica et Cosmochimica Acta; (USA), Journal Name: Geochimica et Cosmochimica Acta; (USA) Vol. 52:3; ISSN GCACA; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400202 -- Isotope Effects
Isotope Exchange
& Isotope Separation
58 GEOSCIENCES
580000* -- Geosciences
ACTINIDE COMPOUNDS
APATITES
CARBONATE MINERALS
CHEMICAL COMPOSITION
CHEMISTRY
COHERENT SCATTERING
DIFFRACTION
DISPERSIONS
ELEMENTS
GEOCHEMISTRY
ION EXCHANGE
KINETICS
MATERIALS
METALS
MINERALS
MIXTURES
MONAZITES
OXYGEN COMPOUNDS
PH VALUE
PHOSPHATE MINERALS
PHOSPHATES
PHOSPHORUS COMPOUNDS
RADIOACTIVE MATERIALS
RADIOACTIVE MINERALS
RARE EARTH COMPOUNDS
RARE EARTHS
REACTION KINETICS
SCATTERING
SOLUBILITY
SOLUTIONS
STRUCTURAL CHEMICAL ANALYSIS
SULFATE MINERALS
SURFACE PROPERTIES
THORIUM COMPOUNDS
THORIUM MINERALS
THORIUM PHOSPHATES
TRANSITION ELEMENT COMPOUNDS
X-RAY DIFFRACTION
XENOTIME
YTTRIUM COMPOUNDS
YTTRIUM PHOSPHATES