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Mg6Fe3+2(CO3)(OH)16.4H2O
Hexagonal
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| Figure 23-27. Platy, sharp-edged crystals of sjögrenite, overgrown on ragged-edged crystals of pyroaurite from Sterling Hill. Field of view is 0.6 mm in maximum dimension. | ||
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Sjögrenite, a magnesium ferric-iron carbonate hydroxide hydrate mineral and a polymorph of pyroaurite, was first noted from Sterling Hill by Dunn and Leavens (1981); it has not been found at Franklin. The crystals are bright orange, with vitreous luster, and occur as sharp-edged, stacked, platy crystals overgrown epitactically on corroded pyroaurite (Figure 23-27).
Sjögrenite was verified using powder X-ray diffraction methods and chemical tests. It is best distinguished from pyroaurite using X-ray methods.
The above-described sjögrenite occurs on the 1300 level at Sterling Hill, on a matrix of calcite- willemite-franklinite ore, which is coated with secondary chlorophoenicite, sphalerite, barite, willemite, and pyroaurite. Sjögrenite is a rare mineral locally.
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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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