Structural segregation in GSR from mercuric primers. A preliminary study

Area of Science:

• Forensic Science
• Materials Science
• Analytical Chemistry

Background:

• Mercury-containing gunshot residue (GSR) from mercuric primers is less studied than lead-based residues.
• Current ASTM standards for GSR analysis do not address mercuric primer residues.
• Forensic interest in Hg-containing GSR persists for ammunition from Eastern Europe and Asia.

Purpose of the Study:

• To characterize the chemical composition and inner morphology of GSR particles from mercuric primers.
• To identify characteristic elements and structures of Hg-containing GSR.
• To investigate the behavior of mercury within GSR particles under analytical conditions.

Main Methods:

• Analysis of GSR particles from three different mercuric primers.
• Focused Ion Beam/Scanning Electron Microscopy (FIB/SEM) for morphological analysis.
• Electron beam analysis to observe mercury behavior.

Main Results:

• SbSnHg residues are proposed as characteristic of discharged mercuric primers.
• GSR particles exhibit inner nodules and inhomogeneities.
• Mercury vaporization was observed under electron beam, attributed to segregation and lattice defects.

Conclusions:

• SbSnHg residues are indicative of mercuric primer discharge.
• Morphological features like inner nodules are common in these GSR particles.
• Mercury's behavior in GSR is influenced by particle formation and lattice structure, leading to potential evanescence during analysis.