Table 3.

Relative amount of elements on the surface compared to Si in new and degraded samples with cracks and bulges (wt.%).

Ratio	B/Si	Na/Si	Mg/Si	Al/Si	K/Si	Ca/Si	Ti/Si	Fe/Si
Etalon	0.76	0.10	0.34	0.43	0.01	0.66	0.04	0.25
Cracks	0.35	0.12	0.38	0.49	0.07	1.17	0.09	0.23
Bulges	0.41	0.09	0.38	0.49	0.06	1.01	0.08	0.19