ramsdellite

ramsdellite

[′ramz·de‚līt]
(mineralogy)
MnO2 An orthorhombic mineral composed of manganese dioxide; it is dimorphous with pyrolusite.
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Manganese oxides are mainly constituted by [Mn[O.sub.6]] octahedra with (1 x n) pyrolusite pore structure in ramsdellite family, barium and manganese ore (2 x n) pore structure in psilomelane family, barium, calcium, and manganese family (3 x n) pore structure, and (1 x [infinity]) layered structure manganese oxide minerals [12, 13].
[gamma]-Mn[O.sub.2] possesses a varying structure and composition, with the De Wolff disorder intergrowth of ramsdellite (1 x 2 tunnel) and pyrolusite (1 x 1 tunnel) [6].
where [T.sub.w] is the Twinning index of [gamma]-Mn[O.sub.2], varying from 0 for perfect ramsdellite (1 x 2 tunnel) structure to 100 for fully twinned structure; [delta]([T.sub.w]) is the Theoretical shift of line 110 in XRD analysis produced by microtwinning; DW is the Logogram for De Wolff; [delta](DW) is the Shift of line 110 in XRD analysis corrected for microtwinning; and [P.sub.r] values were 24.86% for M1 and 43.90% for M2.
Ramsdellite has been identified on only two specimens from Ilfeld.
The new strike of ramsdellite made in November 2008 at the Mistake mine, Yavapai County, Arizona, produced something like 30 flats of thumbnail and miniature specimens, much better on average than the ramsdellite specimens which were dug and marketed in the 1990s by the late Dave Shannon.
Native gold was also reported in the oxidized zones of the silver-rich veins themselves, together with cryptomelane, ramsdellite, romanechite, native silver, and small amounts of chlorargyrite (Meyer et al., 1968).