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Mg6Al2(CO3)(OH)16.4H2O
Hexagonal
Hydrotalcite, a magnesium aluminum hydroxide hydrate mineral, was described from Franklin by Dunn (1979c); it has not been reported from Sterling Hill. It occurs as 1 mm, tabular, whitish, hexagonal crystals which are very soft and flexible. It is fluorescent in longwave ultraviolet with a whitish-yellow response color. It is associated with gahnite, hodgkinsonite, calcite, willemite, and serpentine; calcite and hydrotalcite are the last minerals to form. Semiquantitative microprobe analysis found Mg and Al as major cations, with traces of Mn and Zn; carbonate was indicated by effervescence in HCl, and the identity was confirmed by X-ray diffraction.
Another Franklin occurrence, associated with zincite in a vein assemblage, consists of yellow-brown, bronzy, platy crystals in curved aggregates. These are in an intimate mixture of hydrotalcite, hemimorphite, hauckite, and calcite.
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| Copyright © 1995 by Pete J. Dunn |
Website
by Herb Yeates
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Link
to homepage
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This
page created: January 11, 2001 |
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