Certification of Meissen Granite IAG GMN‐1 Using the GeoPT Proficiency Testing Certification Protocol

Following a full assessment of the GeoPT proficiency testing scheme against the recommendations in ISO Guide 35:2017 for the use of proficiency testing in the certification of reference materials, this paper presents the first application of the GeoPT certification protocol in the characterisation of a new geochemical CRM, IAG GMN-1, Meissen Granite. This protocol is applied to the measurement results reported in Round 51 of the GeoPT programme in which the candidate CRM was used as the test material, together with an established CRM (CGL 008 MGT-1 Granite) to provide validation of the results. Following the presentation of mineralogy, grain-size analysis and homogeneity testing data for IAG GMN-1, certified values for nine major elements and thirty-nine trace elements are reported.