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

Journal Article · Tue Mar 01 00:00:00 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), Vol. 52:3; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

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