SHORT COMMUNICAT IONS 941 REFERENCES

FOUR concentrates of jarosite, KFe~+(OH)6(SO4)~, have been prepared as a by-product of a micropalaeont01ogical nvestigation. Two are from the Barton clay at Alum Bay and the other two are from Whitecliff Bay, Isle of Wight, one in the Barton clay and one in the upper Bracklesham beds. The jarosite was identified by X-ray diffraction, the d-spacings agreeing very closely with those observed by Warshaw (I956). Partial chemical analyses by wet methods confirmed the identification and an X-ray spectrometer scan identified small amounts of Pb, Sr, Ni, Ti, and Ca, which may be substituting in the jarosite. Silver was not detected. The mineral occurs as a yellow, finely crystalline coating on quartz grains and is closely associated with limonite. In the Bracklesham specimen the jarosite forms a gradation from the limonitic staining of a sandstone band within the clays. Also fre-quently present are glauconite and gypsum, this association according with the record of Briggs (i951). Sass et al. (I965) and Pough 0940 reported jarosite associated with gypsum and pyrite. These authors uggest that jarosite results from a series of reaction