Heritage Science

Table 3 EDS-based x-ray microanalyical results for component spectra shown in Fig. 8c

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

Oxide	Al-rich	Mn-rich	Plagioclase
SiO₂	49.3	22.0	62.2
Al₂O₃	43.4	9.9	17.6
CaO
MgO	2.9	2.0
Fe₂O ^b₃		23.5	0.0
K₂O			0.1
Na₂O	4.4	1.8	10.4
MnO^c		40.8	9.6
Oxygens	10	10	8
Cations^a
Si	2.68	1.73	2.86
Al	2.78	0.92	0.96
Ca
Mg	0.23	0.23
Fe		1.39	0.00
K			0.01
Na	0.46	0.28	0.93
Mn		2.71	0.37

Normalized 100 wt%
^aCations based upon number of oxygens
^bTotal iron expressed as Fe³⁺
^cTotal manganese expressed as Mn²⁺

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