Table A1-B -.

Assessment of the accuracy and precision of the bulk-rock major and minor element data generated during this study.

Bulk-rock sample duplicate analyses
	GV1285	GV1285 - duplicate	Ext. Precision (2-sigma)	BO1251	BO1251 - duplicate	Ext. Precision (2- sigma)
Al2O3 (wt%)	4.21	4.19	1%	703%	702%	0%
CaO	3.165	3.174	0%	454%	452%	1%
Fe2O3	45.78	45.7	0%	1426%	1420%	1%
K2O	0.09	0.09	0%	22%	22%	0%
MgO	2.25	2.25	0%	3024%	3027%	0%
MnO	0.047	0.049	6%	20%	19%	3%
Na2O	0.22	0.22	0%	102%	102%	0%
P2O5	0.007	0.007	0%	12%	11%	2%
SiO2	11.45	11.43	0%	4153%	4143%	0%
TiO2	0.16	0.16	0%	90%	90%	0%
Bulk-rock duplicate analyses of reference materials
	OKUM-1	OKUM-2	OKUM-3	Ext. Precision (2-sigma)	IAG preliminary certified value	Deviation of OKUM average from IAG value
Al2O3 (wt%)	7.95	7.98	8.02	1%	7.973	0%
CaO	7.877	7.922	7.939	1%	7.859	1%
Fe2O3	11.76	11.81	11.83	1%	11.81	0%
K2O	0.07	0.05	0.05	41%	0.045	26%
MgO	21.47	21.59	21.7	1%	21.27	1%
MnO	0.183	0.182	0.182	1%	0.181	1%
Na2O	1.08	1.10	1.11	3%	1.14	−4%
P2O5	0.024	0.023	0.024	5%	0.027	−12%
SiO2	43.84	44.01	44.26	1%	44.113	0%
TiO2	0.37	0.38	0.37	3%	0.381	−2%
Bulk-rock duplicate analyses of reference materials
	BHVO-2	GeoReM preferred value	Deviation from GeoReM value*	BIR-1	GeoReM preferred value	Deviation from GeoReM value*
Al2O3 (wt%)	13.67	13.5	1.3%	15.66	15.4	1.7%
CaO	11.556	11.4	1.4%	13.482	13.4	0.6%
Fe2O3	12.43	12.3	1.1%	11.44	11.3	1.2%
K2O	0.51	0.52	−1.9%	0.02	0.03	−33.3%
MgO	7.36	7.23	1.8%	9.79	9.7	0.9%
MnO	0.171	0.17	0.6%	0.18	0.176	0.6%
Na2O	2.21	2.22	−0.5%	1.79	1.81	−1.1%
P2O5	0.275	0.27	1.9%	0.02	0.027	−18.5%
SiO2	50.06	49.9	0.3%	47.85	47.7	0.3%
TiO2	2.74	2.73	0.4%	0.96	0.97	−1.0%