Gold (Au) is an important indicator in many geochemical studies, but the quantification of sub-nanogram Au in rock samples is challenging. Herein, a simple and rapid analytical protocol for the determination of sub-nanogram Au in 1–2 g rock samples is established using graphite furnace atomic absorption spectrometry (GFAAS) after polyurethane foam (PUF) pretreatment. By employing the optimized extraction conditions, Au recovery can reach up to 95% even for 0.1 ng g-1 Au. Six international rock reference materials (RMs) of basalt, diabase, and gabbro were used to validate the feasibility of this protocol. The results are in agreement with previously reported values obtained using instrumental neutron activation analysis (INAA) or inductively coupled plasma mass spectrometry (ICP-MS), where less or the same amount of sample rock powders were used. Furthermore, the rock RMs of TDB-1 and JB-2 are found to be homogeneous with a precision of < 10% (2 RSD) using only 1 g of sample mass, making them suitable for method validation or quality control for inter- laboratory comparison. Owing to its simplicity, speed, reliability, and low cost, this protocol can be used for Au measurement and tracer provenance in the geochemical community.