An occurrence of a 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 of the mineral corresponds to an aluminous-glauconite. The data show that the mineral is most probably a celadonite-muscovite or celadonite-illite mixture, although a celadonite-phengite cannot be entirely discounted. Approximately 10% smectite layers are also present. The results suggest that re-examination of many aluminous glauconites may show them to be mixtures of this type.