Microspectral Analysis of Green Glass Fragments
THE MICROSCOPE
2014, Volume 62:2, pp. 75–81
DOI
https://doi.org/10.59082/VJCV4496
AUTHORS
Michael B. Eyring, John B. Hoang and Matthew C. Lovelace
ABSTRACT
This study is a continuation of efforts to assist criminalists in sorting glass fragments with similar colors that might have originated from different sources. The topic is of particular interest when multiple glass fragments in question are collected under a single item number and submitted for analysis and are compared with known glass fragments. From a criminalist’s point of view, each questioned fragment is an individual item of evidence, and each fragment must be examined to determine if it can be distinguished from others within the same questioned item number.
Color is a logical starting point for distinguishing many glass fragments, but color can present a lessthan- ideal feature due to the varied sizes and thicknesses of fragments that can make visual color comparison inconclusive. The application of microspectrophotometry (MSP) to the partial resolution of this problem can make fragment color sorting more definitive, but the irregular shapes of glass fragments and their large refractive index (RI) difference relative to air makes an immersion mounting technique necessary prior to MSP analysis. These analytical issues were resolved and the MSP sorting technique was applied to a group of 25 green bottles.
Some initial work on this topic was done on wine bottles and other glasses and was presented for discussion at American Academy of Forensic Sciences (AAFS) in San Antonio, TX in 2007, Inter/Micro in Chicago in 2007 and the Scientific Working Group for Materials Analysis (SWGMAT) in Fredericksburg, VA in 2008 (1). An earlier application of this instrumental technique for the detection of synthetic and fake gems was presented at the AAFS meeting in New Orleans, LA in 2005 (2). The current work analyzes green