Phase Decomposition upon Alteration of Radiation-Damaged Monazite-(Ce) from Moss, Ostfold, Norway

The internal textures of crystals of moderately radiation-damaged monazite-(Ce) from Moss, Norway, indicate heavy, secondary chemical alteration. In fact, the cm-sized specimens are no longer mono-mineral monazite but rather a composite consisting of monazite-(Ce) and apatite pervaded by several generations of fractures filled with sulphides and a phase rich in Th, Y, and Si. This composite is virtually a 'pseudomorph' after primary euhedral monazite crystals whose faces are still well preserved. The chemical alteration has resulted in major reworking and decomposition of the primary crystals, with potentially uncontrolled elemental changes, including extensive release of Th from the primary monazite and local redeposition of radionuclides in fracture fillings. This seems to question the general alteration-resistance of orthophosphate phases in a low-temperature, 'wet' environment, and hence their suitability as potential host ceramics for the long-term immobilisation of radioactive waste

FeMnOx-1: A new microanalytical reference material for the investigation of Mn-Fe rich geological samples

Suitable Mn-Fe rich microanalytical reference materials (MRMs) as calibration material for laser ablation-inductively coupled plasma mass spectrometry (LA-ICPMS) have not been available. The United States Geological Survey (USGS) in collaboration with the Max Planck Institute for Chemistry has prepared a synthetic MRM, FeMnOx-1, with elevated mass fractions of MnO (25 g/100 g), Fe2O3 (8.5 g/100 g) and high mass fractions of 25 trace elements varying between 200 and 5000 mg/kg. This new MRM has been designed as calibration material for a wide range of different Mn-Fe deposits, such as desert/rock varnish, ocean crusts and nodules as well as Mn accumulations in soils and lakes. Small-scale and large-scale homogeneity of FeMnOx-1 were tested with three LA systems (200 nm femtosecond, and 193 nm and 213 nm nanosecond lasers) using different spot sizes and fluences. Our results demonstrate that FeMnOx-1 is homogeneous in the pg to mu g and nm to mu m range and therefore well suited for microanalytical applications. The relative standard deviation (RSD) values obtained from repeated measurements are about 2-3% for test portion masses of 5-100 ng, and are comparable to those of the homogeneous NIST SRM610 and USGS GSE-1G reference glasses. Homogeneity of FeMnOx-1 was also verified for a test portion of 0.1 ng. Seven laboratories using five different bulk and microanalytical techniques were involved in the characterization of FeMnOx-1. Small amounts of this MRM can be obtained on request from the authors. (C) 2016 Elsevier B.V. All rights reserved