The iron and manganese minerals in the study area were goethite, siderite, and rhodochrosite and contained a small amount of pyrite, magnetite, and pyrolusite
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SAED intensity profile, plotted as a function of [d.sup.-1] ([nm.sup.-1]), of the sample Mn25 presents the typical peaks of both maghemite and jacobsite  and the presence of manganosite and pyrolusite
influences the symmetry of the peaks at 4.9 [nm.sup.-1] and 6.6 [nm.sup.-1] .
Subsequently when the calcination temperature was further increased to 400[degrees]C the XRD spectra attained were in agreement with pyrolusite
Mn[O.sub.2] (JCPDS number 24-0735).
Manganese is found as braunite, pyrolusite
, psilomelane, and rhodochrosite.
Important minerals of manganese are pyrolusite
manganite and hausmannite (Roberts et al.
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].
More specifically, they suggested that since manganese does not occur free in nature, it must be present within teeth as a mineral such as pyrolusite
(manganese dioxide) and psilomelane (an oxide mineral of manganese and barium), both of which are described as bluish-black with a metallic appearance.
Chan, "pH-dependent mechanisms of methylene blue reacting with tunneled manganese oxide pyrolusite
," Journal of Hazardous Materials, vol.
The standards selected for Mn were birnessite [([(Na, Ca).sub.0.5]([Mn.sup.4+], [Mn.sup.3+]).sub.2] [O.sub.4].1.5[H.sub.2]O), hureaulite ([(Mn, Fe).sub.5][H.sub.2][(P[O.sub.4]).sub.4].4[H.sub.2]O), manganocalcite (Mn-CaC[O.sub.3]), Mn-carbonate (MnC[O.sub.3]), Mn-sulfate (MnS[O.sub.4]), bixbyite ([Mn.sub.2][O.sub.3]), pyrolusite
(Mn[O.sub.2]), and switzerite ([(Mn, Fe).sub.3][(P[O.sub.4]).sub.2].7[H.sub.2]O).
has been used for adsorption of Pb, Zn and Mg ions from their aqueous solution .
The data points plot well within the [Mn.sup.2+] stability field, indicating that Mn is very undersaturated relative to pyrolusite
(Mn[O.sub.2]; Mn concentrations are much lower than [10.sup.-6] M), and is not likely to become saturated unless highly oxidizing conditions are encountered.