Obsidian use in the mosaic of the St. Juvenal church, Narni (Italy): chemical characterization and origin

Heritage Science

Table 1 XRF results expressed as cps (tr: trace)

#	Colour	K	Ca	Mn	Fe	Co	Cu	Pb	Sr	Y	Zr	Nb	Sn	Sb	Ba	La	Ce
1	blue-green		8.2	11	40		154	13					15	125	4.2
2	blue-green		8.7	10	36		141	11	0.43				17	137	4.9
3	blue-green		8.5	11	43		161	13	0.57				11	101	3.3
4	blue-green		6.7	9.2	34		127	8.7	0.29				15	122	4.4
5	blue-green		6.4	8.2	30		121	11	tr				13	111	3.9
6	light blue		12	11	35		132	2.3	0.51				16	165	4.7
7	light blue		6.5	15	40		36	1.4	tr				3.2	48	2.6
8	light blue		11	7.5	36		194	4.2	0.48				18	141	3.4
9	light blue		5.4	4.3	19		106	1.9	0.39				12	119	3.2
10	light blue		7.3	8.2	30		161	3.3	0.47				17	171	3.7
11	dark blue		10	21	49	5.4	18	5.0	0.41				5.1	176	5.3
12	black	2.9	2.1	2.8	134					0.19	1.0	0.29			29	0.90	4.3
13	black	3.6	2.3		147					0.15	1.1	0.34			22	0.70	3.0
14	black	1.9	2.0		86					0.22	0.81	tr			27	0.71	3.8
15	white		120	0.36	2.0
16	colourless		20	8.7	23				0.53				tr	53	4.0
17	colourless		14	11	27				0.53					74	5.6