Cathodoluminescence Dependence On Feldspar Mineral Structure And Implications For Forensic Geology
Document Type
Article
Publication Date
2-2015
Publication Source
American Mineralogist
Volume Number
100
Issue Number
2
First Page
451
Last Page
458
Publisher
Mineralogical Society of America
ISSN
0003-004X
Abstract
A collection of 42 feldspar mineral samples from a wide geographical range of North America was examined by cold-cathode cathodoluminescence (CL) spectroscopy. Characteristic wavelength peaks, which were determined to be independent of geographic origin, were associated with each feldspar phase. Most of these peaks were attributed to previously assigned Mn2+ and Fe3+ luminescent centers and structural defects. An unattributed set of infrared (IR) peaks was observed in many samples; one uncommon ultraviolet (UV) peak was observed in samples from two locations. The peak centroids associated with the Mn2+ and Fe3+ luminescent centers vary with stoichiometric changes in the K-Na-Ca composition of the feldspars. For both alkali and plagioclase feldspars, shifts in CL peak centroids correlate well with lattice size, as measured by X-ray diffraction (XRD). Additional analyses of the feldspar samples by electron microprobe analysis (EMP), particle-induced X-ray emission spectroscopy (PIXE), energy-dispersive micro-X-ray fluorescence spectroscopy (mu XRF), and/or laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) were conducted for confirmation of elemental composition. These results demonstrate the potential of CL spectroscopy, a relatively nondestructive analytical technique, to facilitate rapid discrimination between feldspar samples. The addition of CL spectroscopy of feldspars to existing forensic analytical protocols for geologic materials has the potential to provide support for casework, both to discriminate sources in a forensic comparison, as well as to constrain the provenance of an unknown sample.
Keywords
Luminescence, Feldspar, Forensic Geology, Spectroscopy, Alkali Feldspars, Crystallographic Orientation, Pb+ Centers, Luminescence, Radioluminescence, Elements
Recommended Citation
Brokus, Sarah A., Danielle K. Silletti, J. Mark Lunderberg, Paul A. DeYoung, Graham F. Peaslee, Dyanne E. Carpenter, and JoAnn Buscaglia. “Cathodoluminescence Dependence on Feldspar Mineral Structure and Implications for Forensic Geology.” American Mineralogist 100, no. 2–3 (February 1, 2015): 451–58. doi:10.2138/am-2015-4661.
