The Minerological compositionof some Tasmanian clays

An account is given of the mineralogical composition as determined by X-ray, differential thermal and chemical analyses, of some industrially important Tasmanian clays used in brick and agricultural pipe manufacture and as paper fillers. The clay deposits examined are mainly of Tertiary age and are both residual and sedi­ mentary in origin. Kaolin is the dominant clay mineral in all samples with illite as a minor constituent in most; quartz is abundant in the brick and pipe clays. One sample from Surges Bay shows the presence of a mixed-layer mineral of mont­ morillonite and dioctahedral illite in both randomly stacked and ordered structures. An ordered structure of kaolinite and pyrophyllite or talc may occur also.