8 9Muscovite B4M, distributed in 1961 as an age standard, was ground under ethanol. Five grain size 10 fractions were obtained and characterised by X-ray diffraction. They display a mixing trend 11 between a phengitic (enriched in the fraction < 0.2 µm) and a muscovitic component (predominant 12 in the fraction > 20 µm). High-pressure phengite is preserved as a relict in retrograde muscovite. 13Electron microprobe analyses on the distributed mineral separate reveal at least four white mica 14 populations based on Si, Al, Mg, Na, Fe, and F. Rb/K ratios vary by one order of magnitude.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.