Abstract. In this paper, we present the results of a multi-analytical characterization
of a glaucophane sample collected in the Piedmont region of northwestern
Italy. Investigation methods included optical microscopy, powder X-ray
diffraction, Fourier-transform infrared spectroscopy, µ-Raman
spectroscopy, Mössbauer spectroscopy, electron probe microanalysis,
environmental scanning electron microscopy and energy-dispersive X-ray
spectroscopy, and scanning/transmission electron microscopy combined with
energy-dispersive X-ray spectroscopy and electron energy-loss spectroscopy. In
addition to the crystal–chemical characterization of the sample from the
mesoscale to the near-atomic scale, we have also conducted an extended study
on the morphology and dimensions of the mineral particles. The main finding
is that studying the same particle population at different magnifications
yields different results for mineral habit, dimensions, and dimensional
distributions. As glaucophane may occur as an elongate mineral particle
(e.g., asbestiform glaucophane occurrences in California and Nevada), the
observed discrepancies therefore need to be considered when assessing
potential breathability of such particles, with implications for future
regulations on elongate mineral particles. While the sample preparation and
particle counting methods are not directly investigated in this work, our
findings suggest that different magnifications should be used when
characterizing an elongate mineral particle population, irrespective of
whether or not it contains asbestiform material. These results further
reveal the need for developing improved regulation for elongate mineral
particles. We thus propose a simple methodology to merge the datasets
collected at different magnifications to provide a more complete description
and a better risk evaluation of the studied particle population.
Reaching for atomic-scale quantitative energy dispersive X-ray spectroscopy