(Mg2+,Fe~+)Si4Olo(OH)~. Reports of celadonite

ABSTRACT. An occurrence ofa celadonite-like mineral in a weathered basalt in the Lake District has been investigated by X-ray diffraction, X-ray fluorescence, electron microprobe, and infra-red spectroscopic methods. The bulk composition ofthe mineral corresponds toan aluminous-glauconite. Th data show that he mineral is most probably aceladonite-muscovite or c ladonite-illite mixture, although a celadonite-phengite cannot be entirely discounted. Approximately 10~o smectite layers are also present. The results uggest that re-examination f many aluminous glauconites may show them to be mixtures of this type. C E L A D O N I T E is an iron-rich d ioc tahedra l mica of ideal half-unit cell composition K(Fe3+,A1 a+