Table 2.

Elemental composition of OSR 550 as emerged by energy dispersive X-ray detector (EDX).

Element	Concentration [wt.%]
	Site 1	Site 2	Site 3
C	86.79	90.67	34.45
O	10.82	8.49	42.33
Mg	0.10	0.05	0.29
Si	0.33	0.15	0.41
P	0.12	0.05	0.16
Cl	0.10	0.03	1.88
K	1.32	0.42	20.48
Ca	0.42	0.13	34.45