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Fig. 8 | Heritage Science

Fig. 8

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

Fig. 8

SEM-based x-ray microanalysis of rock cross sections with rock varnish. a Quantified Mn map (threshold >10 atom%) superimposed on backscattered electron (BSE) image of highlighted region in Fig. 7. Qtz quartz, Pl plagioclase feldspar, Afs alkali feldspar, Bt biotite, Ttn titanite, Hem hematite, Cly clay and Ap apatite. b Higher resolution BSE image of a cross section at the rock surface where Mn is concentrated. c RGB overlay of previous with multivariate statistical (MVS) components that model the hyperspectral x-ray data set. Inset: Component spectra associated with red (Al-rich phase), green (Mn-rich phase), and blue (plagioclase) component images

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