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Mn2(AsO4)(OH)
Monoclinic
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Figure 25-38. Typical sarkinite crystals in parallel growth from Sterling Hill. Field of view is 0.4 mm in maximum dimension. |
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Sarkinite was first described from Franklin by Palache et al. (1938), and it was verified by the writer from Sterling Hill (Dunn, 1980).
Sarkinite occurs at Franklin as massive pinkish-red material in 5-7 cm samples. Sterling Hill sarkinite occurs in superb crystals, 1-4 mm in length, (Figure 24-9) and commonly in clusters (Figures 25-38 and 25-40). The crystal habits are diverse, but no morphological studies have been done. Twinning is common, but the composition plane is unhealed (Figure 25-39), resulting in a serrated juncture of faces on terminal forms. The color of Sterling Hill sarkinite varies substantially, from orange to orange-brown to brown. Franklin sarkinite is biaxial, negative, with a = 1.790, b = 1.794, and g = 1.798; dispersion is r < v. X-ray methods are best for verification.
Sarkinite is a manganese arsenate hydroxide mineral. Chemical analyses of sarkinite are given in Table 25; additional analyses of the Franklin material by the writer show that the ZnO content varies from 3.4 to 6.3 wt. %; more analyses are given by Dunn (1980).
Sarkinite occurs at Franklin as massive, pinkish red material, associated with willemite and yeatmanite in the type yeatmanite assemblage. Another uncommon Franklin assemblage is discussed under manganberzeliite.
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| Figure 25-39. Sarkinite crystals from Sterling Hill exhibiting serrated “openings” at their terminations. These crystals have not been examined morphologically for twinning. Photograph at top left shows crystals in subparallel growth. Crystals at bottom left are from right side of upper left photo. Field of view is 0.8 mm for top left photograph and 0.2 mm for the other photographs, in maximum dimension. | ||
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Sarkinite crystals are apparently much more abundant at Sterling Hill, occurring as euhedra on fracture surfaces in brown-willemite ore. It is also found as spherules, pink to brown, commonly associated with rhodochrosite and barite. Occurrences are numerous: it was found on the 1000 level with serpierite, on the 1200 level with copper and adamite, on the 1300 level with allactite, and on the 1400 level with brandtite. It also occurs in the assemblage for type parabrandtite.
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| Figure 25-40. Stout, prismatic crystals of sarkinite from Sterling Hill. Field of view is 0.6 mm in maximum dimension. | ||
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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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