Caption: Figure 1: Simulated several morphologies of Hollandite
Mn[O.sub.2] models, where (a) [alpha]-Mn[O.sub.2] crystal ([Mn.sub.8][O.sub.16]), (b) (100) bulk surface ([Mn.sub.32][O.sub.64], M(100)), (c) (110) bulk surface ([Mn.sub.16][O.sub.32], M(110)), (d) [(100 x 110)] microfacet ([Mn.sub.32][O.sub.64], M[(100 x 110)]), (e) nanorod(I) ([Mn.sub.28][O.sub.56], MNR(I)), (f) nanorod(II) ([Mn.sub.68][O.sub.136], MNR(II)), and (g) nanorod(III) ([Mn.sub.112][O.sub.224], MNR(III)).
One example is hollandite
that is dug out of the Italian Alps and shows promise for housing cesium.
It is interesting to note that Ti[O.sub.2] exists in six different polymorphs, namely, rutile (tetragonal), anatase (tetragonal), brookite (orthorhombic), Ti[O.sub.2] (B) (monoclinic), Ti[O.sub.2] (II) (alpha-Pb[O.sub.2]), and Ti[O.sub.2] (H) (hollandite
) [56, 57].
Mineralogical composition of the fines at Balaghat and Ukwa mines is similar in nature and consists of Hollandite
, Braunite, Psilomelane, Hematite, Apatite and Quartz.
French scientists summarize results from their research into hollandite
, zirconolite, zirconolite-base glass-ceramics, and borosilicate glasses as matrices in which to store highly radioactive nuclear waste for a very long time.
The system contains at least four ternary phases: [Ba.sub.x][Zn.sub.x][Ti.sub.8-x][O.sub.16] with the Hollandite
structure, [Ba.sub.4][ZnTi.sub.11][O.sub.27], [Ba.sub.2][ZnTi.sub.5][O.sub.13], and [BaZn.sub.2][Ti.sub.4][O.sub.11].
Neth et al., "Synthesis and characterization of Octahedral Molecular Sieves (OMS-2) having the hollandite
structure," Chemistry of Materials, vol.
The rarest specimens include scepters, crystals with moveable gas bubbles in fluid inclusions, fuschite inclusions, and star-shaped hollandite
One sample gave an XRD pattern that is a fairly good match for hollandite
. Another, poorer, pattern is a fair match for cryptomelane, K[Mn.sub.8][O.sub.16]
A sub-district of this district is Animas-Chocaya district, Ferberite Aullagas See Colquechaca Avicaya Cassiterite, jarosite, stannite, vivianite Ayoreita Amethyst, hollandite
, smoky quartz Berenguela Cassiterite, pyrite, pyrrhotite, silver sulfosalts Berenguela Apatite, greenockite, quartz, siderite, sphalerite.
Associated minerals are: braunite, quartz, the "violan" variety of diopside-aegirine-jadeite, strontiopiemontite, hollandite
, cryptomelane, jadeite, antimony-bearing titanite and arsenic-bearing titanite and arsenic-bearing fluorapatite.