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Bentonitic beidellite-mudstone from the Faeroe Islands
Published online by Cambridge University Press: 09 July 2018
Abstract
A Tertiary mudstone from beneath worked coal among the basalts of the Faeroe Islands is mainly composed of aluminium-rich dioctahedral smectite, disordered kaolinite (amounting to about one quarter of the smectite) and probably about 13 ~ amorphous material. The texture is the result of crystallization in place. Chemical analysis suggests an ionic formula for the smectite of (Ca0.32Na0.10K0.04) (A13.88 Fe0.06+3Fe0.05+2Mg0.29) (Si6.71 A11.29) O20 (OH)4· 3·0 H20, which corresponds closely to beidellite. The total charge on the interlayer cations is 0·78 and cationexchange capacity is 52·5 meq/100g. DTA curves yielded endothermic peaks at 140°C, 220°C, and 555°C with an exothermic peak at 955°C. The nomenclature is discussed and the material considered to be a bentonitic beidellite-mudstone; the rock, which has crystallized in place has similarities with tonstein in its mode of formation.
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- Copyright © The Mineralogical Society of Great Britain and Ireland 1971
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