Determination of gold abundances in natural rock is critical for applications, but very challenging.  Here we report a method for determining gold with a very low mass fraction (> 0.01 ng g-1) in rocks.  The method involves Carius tube digestion with reverse aqua regia, chromatographic separation to  remove most of the sample matrix and measurement by high-sensitivity ICP-MS. The mono-isotopic  element gold is quantified by external calibration using an internal standardisation of gold to platinum  that is precisely determined by isotope dilution. The method is robust and the obtained results are  indistinguishable (< 5–10%, 2s) from those independently obtained by a standard addition technique  on the same solution. The results from reference materials TDB-1 and GPt-2 are consistent with the  certified values and those determined by HF-aqua regia digestion, confirming the validity of the  method. TDB-1 (n = 20), GPt-2 (n = 6), BHVO-2 (n = 9) and other mafic RMs are homogenous for  gold (10–20%, 2s) at the 2-g test portion level, however, sample heterogeneity affects some RMs.  Gold and platinum-group elements also display different extents of sample heterogeneity for different  RMs. Given the homogeneity observed for TDB-1, GPt-2 and BHOV-2, they are recommended as  well-suited RMs for gold for inter-laboratory comparison.