Oceana Gold Waihi North Project Waihi North Project Geochemical Assessment – Geochemistry of Tailings and Overburden, Treatment and Mitigation Revision 9 – 17-Jun-2022 Prepared for – Oceana Gold (New Zealand) Limited – Co No.: 2274246 A-6 AECOM Table 30 2-Acid and 4-Acid Digestion Method Comparison Dataset Mean P-Value* Dataset used 2-Acid 4-Acid nmax 157# 157 Al 0.49 4.67 <0.01 4-Acid As 144 156 NS 2-Acid Ba 43 140 <0.01 4-Acid Ca 0.04 0.05 <0.01 2-Acid Cd 0.25 0.09 <0.01 2-Acid Co 12.5 11.5 NS 2-Acid Cr 8.4 43.4 <0.01 4-Acid Cu 16.4 17.0 NS 2-Acid Fe 3.0 3.0 NS 2-Acid K 0.12 0.95 <0.01 4-Acid Mg 0.04 0.15 <0.01 4-Acid Mn 55 82 <0.01 2-Acid with 4-Acid correction applied Mo 1.1 1.5 <0.01 2-Acid with 4-Acid correction applied Na 0.01 0.02 NS 2-Acid Ni 12.4 13.0 NS 2-Acid Pb 7.2 9.3 <0.01 2-Acid with 4-Acid correction applied S 2.7 2.6 NS 2-Acid Sb 17.2 60.7 <0.01 4-Acid Se 2.2 3.0 <0.01 2-Acid with 4-Acid correction applied V 8.5 78.0 <0.01 4-Acid Zn 15.7 19.5 <0.01 2-Acid #The number of 2-Acid samples given is only reflective of where there is a corresponding 4-Acid sample. *P-Value calculated using the Wilcoxon–Mann–Whitney test to compare 2-acid data distribution with the 4-acid data distribution. P-Values < 0.01 provide strong evidence against the null hypothesis (which in this case assumes that 2-acid and 4-acid data distributions are identical). P-Values labelled as not significant (NS) are sufficiently high to infer 2-acid data and 4-acid data distributions are consistent with the null hypothesis. Difference is attributed to difference in detection limits
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