Mining & Minerals

Research Reports from University of Pisa Provide New Insights into Mineralogy

  2011 JUN 3 - (VerticalNews.com) -- "Gelosaite, BiMo(2-5x)6+Mo6x5+O7(OH)center dot H2O (0 <= x<= 0.4), occurs at the type locality in quartz veins hosted by granitic rocks at Su Senargiu, near Sarroch, Sardegna, Italy. The name is in memory of Mario Gelosa (1947-2006) who first found the mineral," scientists in Pisa, Italy report.

  "The mineral also occurs in the oxidized zones of the Old 25 and Wolfram pipes at Kingsgate, New South Wales, Australia. Both the mineral and its name have been approved by the IMA CNMNC (IMA 2009-022). Gelosaite occurs as yellow, yellowish green, and pale blue, prismatic crystals with a white streak. It is transparent with an adamantine luster, non-fluorescent, brittle, and has a conchoidal fracture. Mohs hardness is similar to 3. The mineral is monoclinic, space group P2(1)/n, with a = 5.8505(4), b = 9.0421(6), c = 13.917(1) angstrom, beta = 100.42(1)degrees, V = 724.1(1) angstrom(3), Z = 4 (yellow Su Senargiu crystal); a = 5.8570(5), b = 9.0517(8), c = 13.992(1) angstrom, beta = 100.44(1)degrees, V = 729.5(1) angstrom(3), Z = 4 (pale blue Su Senargiu crystal); a= 5.837(3), b = 9.040(5), c = 13.904(7) angstrom, beta = 100.64(1)degrees, V= 721.0(6) angstrom(3), Z = 4 (blue Kingsgate crystal). Strongest lines in the powder X-ray pattern [d (angstrom)(I-ret)] are 4.83(100), 3.41(21), 3.30(25), 3.015(50), 2.755(60), 2.080(50), 1.688(20), and 1.509(30). The single-crystal X-ray structure of gelosaite was determined for three separate crystals, two from Su Senargiu and one from Kingsgate. The structure consists of layers of distorted MoO6 octahedra, plus minor amounts of interstitial Mo ions, and layers made up of eight-coordinate Bi3+ ions, plus further small amounts of interstitial Mo ions. The theoretical Mo(VI) end-member has the stoichiometry BiMo26+O7(OH)center dot H2O and excess Mo in the interstices requires increasing amounts of Mo(V) to be present," wrote P. Orlandi and colleagues, University of Pisa.

  The researchers concluded: "The theoretical Mo(V) end-member has the stoichiometry BiMo2.45+O7(OH)center dot H2O."

  Orlandi and colleagues published their study in American Mineralogist (Gelosaite, BiMo(2-5x)6+Mo6x5+O7(OH)center dot H2O (0 <= x <= 0.4), a new mineral from Su Senargiu (CA), Sardinia, Italy, and a second occurrence from Kingsgate, New England, Australia. American Mineralogist, 2011;96(2-3):268-273).

  For additional information, contact P. Orlandi, University of Pisa, Dipartimento Science Terra, Via S Maria 53, I-56126 Pisa, ITALY.

  The publisher's contact information for the journal American Mineralogist is: Mineralogical Society American, 3635 Concorde Pkwy Ste. 500, Chantilly, VA 20151-1125, USA.

  Keywords: City:Pisa, Country:Italy, Region:Europe, Electrolytes, Ions, Mineralogy

  This article was prepared by VerticalNews Mining & Minerals editors from staff and other reports. Copyright 2011, VerticalNews Mining & Minerals via VerticalNews.com.