page_title: Anatase
section_title: See also
hierarchical_section_title: Anatase / See also
caption_attribution_description: English: Anatase, Quartz Locality: Hardangervidda, Hordaland, Norway (Locality at mindat.org) Size: 9.3 x 2.6 x 2.8 cm. This is a stunning, complete all-around and water-clear, slightly smoky quartz crystal that is festooned with lustrous anatase crystals to 9 mm. It is from the classic locale of from Hardangervidda, Norway. The anatase crystals are embedded both on and within the smoky quartz, uncommon for the locality. Ex. Dr. Gary Hansen, Smithsonian, Geology Museum at the University of Oslo Collections. Deutsch: Anatas, Quarz Fundort: Hardangervidda, Hordaland, Norwegen (Fundort bei mindat.org) Größe: 9.3 x 2.6 x 2.8 cm.
context_page_description: Anatase is a metastable mineral form of titanium dioxide. The mineral in natural forms is mostly encountered as a black solid, although the pure material is colorless or white. Two other naturally occurring mineral forms of TiO₂ are known, brookite and rutile.
  Anatase is always found as small, isolated and sharply developed crystals, and like the thermodynamically stable rutile, it crystallizes in the tetragonal system. Anatase is metastable at all temperatures and pressures, with rutile being the equilibrium polymorph. Nevertheless, anatase is often the first titanium dioxide phase to form in many processes, due to its lower surface energy, with a transformation to rutile taking place at elevated temperatures. Although the degree of symmetry is the same for both anatase and rutile phases, there is no relation between the interfacial angles of the two minerals, except in the prism-zone of 45° and 90°. The common pyramid of anatase, parallel to the faces of which there are perfect cleavages, has an angle over the polar edge of 82°9', the corresponding angle of rutile being 56°52½'.
context_section_description: List of minerals
  Adularia
  Delustrant
caption: Black anatase crystals on smoked quartz
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