Research Progress on the Development of Global Gold Ore Reference Materials and the Nugget Effect

Reference materials serve as the benchmark for measuring the accuracy of test results. Both domestically and internationally, continuous efforts are made to develop various types of reference materials to support sample testing quality control, metrological traceability, and legal arbitration. Currently, significant gaps exist between China’s certified reference materials (CRMs) for gold ores and the actual demands, particularly concerning diversity, coverage of certified elements, and representation of low-grade segments. Drawing on international experience in gold ore CRM development—characterized by rich variety, numerous certified elements, and a high proportion of low-grade materials—can better serve the new round of strategic mineral exploration breakthroughs. Leveraging big data from domestic and international resource-sharing platforms, this paper systematically reviews the current status and key technical bottlenecks in gold ore CRM development globally. As of June 2025, over 160 certified gold ore CRMs are available internationally, exhibiting features such as diverse types, multiple certified elements, and a high proportion of low-grade materials (40% in the 0.104-1 ppm range). Candidate materials encompass various rock and ore types, including greenstone, granite, volcanic rock, metamorphic rock, and quartz conglomerate. Certified elements include Au, Ag, Cu, Mo, Sb, Al, and other associated elements. In contrast, China possesses 74 certified gold ore CRMs. The candidate materials are primarily limited to three gold deposit types: quartz-vein type, altered-rock type, and Carlin type. Certified elements are mainly Au alone or Au-Ag pairs, with only 5 CRMs featuring multi-element certification. The proportion of low-grade materials is small (only 12% in the 0.2-1ppm range). This comparison reveals domestic shortcomings, including limited ore type diversity, narrow elemental certification scope, and insufficient coverage of low-grade segments. Through in-depth analysis of technical challenges across gold ore processing stages, this paper identifies the “nugget effect” as a critical bottleneck constraining the diversity of CRM types and demonstrates the inapplicability of laser diffraction particle size analysis for checking the grind size of gold ores. To address these gaps and challenges, this paper proposes the following initiatives: Enhance research on gold ore processing methodologies (especially targeting the nugget effect) and develop specialized equipment (e.g., large disc mills, specialized Raymond mills); Systematically develop series of CRMs for gold ores from China’s typical metallogenic belts; Implement simultaneous certification of gold and associated elements; Prioritize the development of CRMs covering the boundary grade to industrial grade range, particularly the low-concentration segment. These measures aim to resolve the issue of quality control “loss of control” caused by matrix differences between reference materials and actual samples, thereby providing robust support for the global gold industry chain encompassing exploration, mineral processing and metallurgy, and trade.