Near-Surface Chemical Alteration of Nineteenth ...

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Edward P. Vicenzi1,2, Carol A. Grissom1, A. Elena Charola1, Emily Aloiz1, ... Cast stone is broadly defined as architectural concrete that mimics cut stone in.
1416 doi:10.1017/S1431927613009070

Microsc. Microanal. 19 (Suppl 2), 2013 © Microscopy Society of America 2013

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Downloaded from https://www.cambridge.org/core. IP address: 185.145.66.220, on 15 Dec 2017 at 18:40:05, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/S1431927613009070

Microsc. Microanal. 19 (Suppl 2), 2013

1417

Chemical Zones

10 μm

F-rich S-rich mixed Ca sulfate + Ca carbonate

1 North5

2

3

100 μm

Chemical Phase Binary Masks

B F

C

Ca/F 1:/1.97

Ca/S/O

O 1/.96/4.9

4A

Ca

S Ca

3 μm

Figure 1. Photograph of the Smithsonian’s Arts and Industries Building exterior showing circular architectural decorative elements (medallions) interspersed above arched windows. Figure 2. Medallion (diameter = 61 cm ) with white arrow indicating sampling site. Figure 3. Chemical zonation in a polished cross section of cast stone as a function of depth from the surface. Red, green, and blue false color images represent multivariate statistical components of the X-ray data cube for the cement superimposed upon a BSE image with an overlay of their respective component spectra (inset: overview BSE image of examined region-white rectangle). Figure 4. A) Detail of area highlighted in Fig 3. at the interface between the F- and S-rich zones. Chemical phase masks are superimposed on a BSE image representing the fluorine-rich (red) and sulfur-rich (green) zones whose interface is denoted by a dotted line. B) and C) Phase spectra derived from red and green pixels for F-rich (B) and S-rich (C) phases. Elemental ratios of major X-ray peaks in the spectra are expressed on an atom basis.

Downloaded from https://www.cambridge.org/core. IP address: 185.145.66.220, on 15 Dec 2017 at 18:40:05, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/S1431927613009070