• Question: What are the uses of roselite?

    Asked by atixs to Dalya, Derek, Sarah, Tim, Tom on 19 Jun 2011.
    • Photo: Dalya Soond

      Dalya Soond answered on 16 Jun 2011:

      It is to be looked at and admired for its beauty, and possibly treasured as part of a rare mineral collection.

      (I had to look this up).

    • Photo: Sarah Thomas

      Sarah Thomas answered on 16 Jun 2011:

      you can use it to make pretty jewelery!! 😀

    • Photo: Tim Millar

      Tim Millar answered on 16 Jun 2011:

      And you can do raman spectroscopy on it too!

      Spectrochim Acta A Mol Biomol Spectrosc. 2009 Jan;71(5):1788-94. Epub 2008 Jul 9.
      Raman and infrared spectroscopy of arsenates of the roselite and fairfieldite mineral subgroups.
      Frost RL.
      SourceSchool of Physical and Chemical Sciences, Queensland University of Technology, Brisbane, Queensland 4001, Australia.

      Abstract
      Raman spectroscopy complimented with infrared spectroscopy has been used to determine the molecular structure of the roselite arsenate minerals of the roselite and fairfieldite subgroups of formula Ca(2)B(AsO(4))(2).2H(2)O (where B may be Co, Fe(2+), Mg, Mn, Ni and Zn). The Raman arsenate (AsO(4))(2-) stretching region shows strong differences between the roselite arsenate minerals which is attributed to the cation substitution for calcium in the structure. In the infrared spectra complexity exists with multiple (AsO(4))(2-) antisymmetric stretching vibrations observed, indicating a reduction of the tetrahedral symmetry. This loss of degeneracy is also reflected in the bending modes. Strong Raman bands around 450 cm(-1) are assigned to nu(4) bending modes. Multiple bands in the 300-350 cm(-1) region assigned to nu(2) bending modes provide evidence of symmetry reduction of the arsenate anion. Three broad bands for roselite are found at 3450, 3208 and 3042 cm(-1) and are assigned to OH stretching bands. By using a Libowitzky empirical equation hydrogen bond distances of 2.75 and 2.67 A are estimated. Vibrational spectra enable the molecular structure of the roselite minerals to be determined and whilst similarities exist in the spectral patterns, sufficient differences exist to be able to determine the identification of the minerals.

    • Photo: Derek McKay-Bukowski

      Derek McKay-Bukowski answered on 16 Jun 2011:

      Despite a year of geology at university, I didn’t know this one and had to look it up.

      Good question!

    • Photo: Tom Crick

      Tom Crick answered on 19 Jun 2011:

      I had to look up roselite: it is a rare arsenate mineral (dark rose red or pink) with chemical formula: Ca2(Co,Mg)[AsO4]2·H2O.

      Not sure of its uses, maybe for jewellery?

      Question for you: what do you know about roselite?

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