Two reference samples, Albite AL‐I and Iron Formation sample IF‐G were analysed for their chemical composition by the International Working Group “Analytical Standards of Minerals, Ores and Rocks” (GIT‐IWG). AL‐I was processed in 189 kg and IF‐G and 760 kg. 103 GIT‐IWG laboratories participated in this collaborative study along with 171 geoanalysts. This study lasted 15 months (September 1982 ‐ December 1983) and is the second undertaken by the GIT‐IWG. Over 2400 units of data were collated. As a result of this international study, the major and minor elements have been well characterized in both the samples; however, more data on trace elements will be very welcome for a better definition of trace elements, although working values have been proposed for about forty trace elements in each sample. The first and the second collaborative studies undertaken by GIT‐IWG demonstrate well the immense analytical pot