“Sharply-formed, pseudo-hexagonal muscovite crystal. Dark, dusky color comes from microscopic inclusions of iron and manganese oxides and hydroxides like these: https://www.mindat.org/photo-905081.html Crystal also shows patches of bright iridescence from thin-film interference caused by tiny gaps between the muscovite sheets due to the inclusions.”

“Reverse side of sharply-formed, 6.5 cm tall, pseudo-hexagonal muscovite crystal. Collected by Dick Schooner. Harold Moritz specimen.”