Potassium Isotope Ratios (δ41K) of Eighteen Chinese Rock Reference Materials

Potassium isotope ratios ( δ 41 K) were determined for eighteen Chinese geological reference materials (RMs, GSR series) encompassing igneous, metamorphic and sedimentary rocks. K 2 O mass fractions ( w ) ranged between 0.15 and 7.5% in these RMs. Measurements were conducted using a collision cell MC‐ICP‐MS with sample‐standard bracketing technique. The intermediate precision of K isotopic determination, based on measurement results collected over 2.5 years, was 0.04‰ (2 s , n = 69) for in‐house GSB K solution and 0.05‰ (2 s , n = 63) for basaltic RM BCR‐2. The accuracy of our data was assessed by comparison with previously published data and/or utilising two or three different measurement procedures. The high‐precision δ 41 K values for these eighteen RMs span a wide range from ‐1.15‰ (GBW07122, GSR 15, amphibolite) to 0.28‰ (GBW07120, GSR 13, limestone), and data for six RM are presented for the first time, making them valuable references for quality assurance and inter‐laboratory comparisons.