Standard Guide for Forensic Analysis of Geological Materials by Powder X-Ray Diffraction

Importancia y uso:

5.1 The overarching goals of the forensic analysis of geological materials include (A) identification of an unknown material (see 11.3), (B) analysis of soils, sediments, or rocks to restrict their possible geographic origins as part of a provenance analysis (see 11.4), and (C) comparison of two or more samples to assess if they could have originated from the same source or to exclude a common source based on observation of exclusionary differences (see 11.5). XRD is only one analytical method that can be applied to the evidentiary samples in service of these distinct goals. Guidance for the analysis of forensic geological materials can be found in Refs (2-4).

5.2 Within the analytical scheme of geological materials, XRD analysis is used to: identify the crystalline components within a sample; identify the crystalline components separated from a mixture, typically clay-sized material (see 8.8), or a selected particle class for which additional analysis is needed (see 8.11); or compare two or more samples based on the identified crystalline phases or diffraction patterns (see 11.5).

5.2.1 Non-destructive XRD analysis can be performed in situ on geological material adhering to a substrate (see 8.12.3).

5.2.2 The most common forensic applications of XRD to geological materials are (A) identification or confirmation of a selected phase or fraction of a sample (see 8.12), (B) identification of minerals in the clay-sized fractions of soils (see 8.8), and (C) identification of the phases of the hydrated cement component of concrete or mortar.

5.3 This guide is intended to be used with other methods of analysis (for example, polarized light microscopy, scanning electron microscopy, palynology) within a more comprehensive analytical scheme for the forensic analysis or comparison of geological materials.

5.3.1 Comprehensive criteria for forensic comparisons of geological material integrating multiple analytical methods and provenance estimations (see 11.4) are not included and are beyond the scope of this guide.

Subcomité:

E30.15

Referida por:

E1732-24E01

Volúmen:

14.02

Número ICS:

07.140 (Forensic science), 71.040.50 (Physicochemical methods of analysis), 91.100.15 (Mineral materials and products)

Palabras clave:

cement; concrete; forensic; geology; soils minerals; X-Ray diffraction;