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Forensic Microscopy of Glass (1712)


Manufacturing procedures and their impact on glass morphology will be covered. A variety of natural sources of glass will be introduced, and their characteristic morphologies studied.

Refractive index measurements will be treated in detail, including immersion using dispersion staining and variation of both temperature and wavelength. Scanning electron microscopy with energy dispersive X-ray analysis will be used for semi-quantitative elemental analysis of glass fragments.

Advantages and limitations of the method will be determined, with an emphasis on the reliability of the data and the interpretations. Given the data from the light and electron microscopy, the added value of other analytical methods will be considered.

Prerequisite: 1201 or equivalent.

Day 1
• Basics of light microscopy
• Köhler illumination
• Micrometry
• Basics of refractive index methods: Becke line, dispersion staining, phase contrast
• Glass types: Natural sources [animal (radiolarian), vegetable (diatoms, plant opal), mineral (pumice, obsidian, perlite, etc.)], stress and morphology
• Man-made sources of glass: float glass process, molded glass, blown glass, compositions
• Glass fibers: mineral wool, ceramic wool, fiber glass

Day 2
• Dispersion staining
• Measurements of dispersion: use of C, D and F filters, use of interference wedges, use of the Lomo disk
• Hot Stage methods: Grim (phase contrast with hot stage), Mettler hot stage, double-variation method
• Analysis of glass samples

Day 3
• Forensic examination and classification: color, steteromicroscopy, fluorescence microscopy, interference microscopy, polarized light microscopy

Day 4
• Particle handling: tungsten needles, polyethylene pipettes, temporary mounts for storage and refractive index, mounts for SEM/EDS
• Electron microscopy and elemental analysis

Day 5
• Continued laboratory practice

Note: This course runs Monday-Friday with class ending at noon on Friday.