Report (1968–1978) on Two Mica Reference Samples: Biotite Mica‐Fe and Phlogopite Mica‐Mg

Since 1967–68, two mica reference samples, Biotite Mica‐Fe and Phlogopite Mica‐Mg, were made available to several geochemical laboratories. The analytical data reported during the past ten years by 142 geoanalysts belonging to 74 international laboratories are presented and assessed for deriving preferred values. Reaomrmended or proposed values are assigned for major, minor and several trace elements. The biotite Mica‐Fe is better characterized for its chemical composition than the Phlogopite Mica‐Mg. Both the samples are also proposed as geochronological standards. Because very few mica reference samples have been processed in large quantities, the international geochemiaal community is invited to contribute further useful data.