International Association of Geoanalysts Certificate of Analysis: Certified Reference Material OU‐6 (Penrhyn Slate)

The certified concentrations are given in Table 1 for ten major oxides and thirty-five trace elements; information values are given for nine other oxides/elements in the same table. The values are based on measurements using two or more independent analytical techniques. In some cases, definitive methods (e.g., gravimetry for major oxides, isotope dilution-mass spectrometry (ID-MS) for a select few elements) have been used, though generally, certified values were established using comparative analytical techniques.