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Heritage Science
Fig. 6 | Heritage Science

Fig. 6

From: Rock varnish on architectural stone: microscopy and analysis of nanoscale manganese oxide deposits on the Smithsonian Castle, Washington, DC

Fig. 6

Portable x-ray fluorescence spectra of a gatepost surface flake with rock varnish. XRF spectral comparison of the bulk sandstone (Sst) versus rock varnish + bulk spectrum. The grey arrow marks a spectral artifact in the black spectrum at 4.16 keV caused by the escape peak for Mn Kα.The large dynamic range of XRF data requires a log scale plot. Inset hand specimen images of the flake exterior (left) and interior fracture surface (right)

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