The Microscope – Volume 63, Fourth Quarter 2015

IN THIS ISSUE
On the cover
This light photomicrograph shows a cross section of humantissue, with black pigment particles of a tattoo located in the light pink dermal layer; viewed at ≈ 1,000×. See Microscopyand Microanalysis of Tattoo Inks on page 147.(Photo courtesy of Michelle D. Miranda)
Editorial | The PLM’s Indelible Mark on Pigment Research
Gary J. LaughlinThe Microscope 63:4, p. ii, 2015https://doi.org/10.59082/FNIA6906 Excerpt: Anyone who has ever read The Microscope or used a microscope in any analytical way has probably considered the instrument’s long history or thought about what the future may hold for microscopy.
Microscopy and Microanalysis of Tattoo Inks
Michelle D. Miranda The Microscope 63:4, pp. 147–160, 2015https://doi.org/10.59082/AFWN7839
Abstract: In forensic science, the recognition of inorganic and organic pigments in human tissue can aid in the identification of charred, decomposed, mummified or otherwise unidentifiable human remains. In the fields of art conservation and cultural heritage, the characterization and archiving of organic pigments found in traditional tattoo inks can aid in future anthropological and archaeological studies of human culture and history. This research explores the application of microscopical and spectroscopical methods employed in the analysis of modern organic pigments found in tattoo inks. The aim of this research was to scientifically evaluate these inks by documenting their physical and optical properties with macroscopical and microscopical methods and identify the chemical properties of the pigments through spectroscopical analysis. Analytical methods included Fourier transform-infrared spectroscopy (FT-IR), Raman spectroscopy, surface-enhanced Raman scattering (SERS), ultraviolet/visible spectrophotometry (UV/Vis) and X-ray fluorescence (XRF). The lack of an established method for analyzing tattoo inks and a comprehensive database for comparing them were additional catalysts for this research.
Analytical Approach for Identification of the Zeolite Erionite
Kristina P. Pourtabib and Mickey E. GunterThe Microscope 63:4, pp. 161–171, 2015 https://doi.org/10.59082/RCMW2972 Abstract: The need for precise identification of the fibrous/acicular zeolite mineral erionite has become increasingly important due to erionite’s ties to mesothelioma in Turkey and to lung disease in western North America (1). The regulatory community struggles to unambiguously identify asbestiform minerals when they occur in natural rather than built environments. Zeolites present an even more unique set of problems due to the similar cation content and crystal structure observed between different zeolite species such as erionite and offretite. Currently, there is a lack of regulatory methods for accurately identifying erionite particles in nature. We tested a variety of techniques that can be applied for the identification of erionite, including the use of selected area electron diffraction (SAED) with transmission electron microscopy (TEM), indirect zeolite identification with polarized light microscopy (PLM), and powder X-ray diffraction (XRD) for analysis of bulk composition. We found that smaller TEM-scale data provides paramount structural information in the form of diffraction patterns because erionite shows systematic absences (i.e., diffraction constraints) along uv0 of 00l = 2n due to its space group symmetry, while the other zeolites in this study will show different diffraction constraints along c*, and different repeats in c (2). We have shown that by using a combination of scale-dependent identification methods, such as TEM, PLM and XRD, these zeolites can be accurately distinguished from one another with sufficient care.
Polarized Light Microscopy for Determining the Principal Refractive Indices of Components in Polished Thin Sections (Part 2 of 2)
Franz W. NentwichThe Microscope 63:4, pp. 173–187, 2015 https://doi.org/10.59082/UZLX7935 This is the second part of a two-part article. The first part was published in Vol. 63, No. 3. Abstract: In 1767, the Duc de Chaulnes determined the refractive index (RI) n of a glass plate with a compound microscope from the equation, Refractive Index ≈ Real Thickness/Apparent Thickness. This method was adapted by Sorby in 1877 to determine the principal RIs of mineral plates. For thin sections the method was hampered by the difficulty of identifying a section’s underside with transmitted light, but this surface can be identified easily with incident darkfield illumination. Another complicating factor, the effect of permanent coverslips can be avoided with uncovered polished thin sections. Transmitted circularly polarized and circularly analyzed light expedites the selection of suitably oriented anisotropic crystals, and guided by their interference figures, these crystals can be rotated into the orientations needed to measure principal RIs. The ω RI of uniaxial crystals can be determined from crystals in any random orientation, while the ε, α, β and γ indices can be determined with a narrow slit, the long axis of which is oriented perpendicular to the analyzer’s privileged direction. Accuracy is attained by calibration with a RI standard and by accurate measurements of axial translations of the microscope stage relative to the microscope tube.
Afterimage | Grandma’s Wallpaper
Kelly M. Brinsko — McCrone Research Institute The Microscope 63:4, p. 192, 2015 This photomicrograph shows the crystals produced from a microcrystal test for the drug oxycodone using a platinum bromide reagent. Brinsko’s image was selected Most Unique Photomicrograph in the Inter/Micro 2015 Photomicrography Competition.
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