HRL was approached by a client to conduct a foreign matter analysis/fragment analysis on two stones that were embedded in coloured glass. The client was interested in determining the composition and origin of the inclusions (stones). The inclusions(stones) were irregular in shape and had a rough texture, with tiny black dots or spheres visible within the grey matrix.
Identification of Composition of Inclusions in Glass
HRL assists client with foreign object analysis
Challenge
Solution
In order to identify the inclusions/stones, a combination of analytical methods were used. The stones were initially examined under stereoscopic optical microscope to determine their general features and composition. The partially exposed stone surfaces showed that both stones were similar in features, with irregular shapes and a grey matrix. The black spheres within the matrix were also visible, and were found to have a shiny, lustrous, metallic appearance.
The stones were then cut in order to expose fracture surfaces, which were then examined using the scanning electron microscope with an X-ray detector attachment (SEM/EDX). SEM/EDX allowed for a more detailed analysis of the stones' composition and structure, as well as the metallic spheres within them. The SEM images revealed that the stones had a complex internal structure, with multiple layers and regions of different composition.
SEM/EDX allowed for a quantitative analysis of the elements present in the spheres, as well as their relative concentrations. The EDX analysis confirmed the presence of silicon, iron, manganese, titanium, and chromium, as well as other elements such as aluminium, nickel, and copper. The relative concentrations of these elements varied between the different spheres, suggesting that they may have formed under different conditions or from different sources.
Results
The analysis conducted by HRL revealed several key findings about the composition and origin of the stones. The stones were composed of a grey matrix with multiple layers and regions of different composition. The metallic spheres were mainly composed of silicon, with only traces of iron, chromium, and manganese detected in the composition. The relative concentrations of the elements varied between the different spheres. The complex internal structure of the stones suggested they may have been formed through a process involving the melting and solidification of metal alloys. The stones are a result of aluminium contamination in the recycled glass (cullet), which could have come from various sources such as bottle caps, foil labels, pull tabs, aluminium cans, or aluminium machinery parts or tools.
