BOBJONESITE, V4+ O (SO4) (H2O)3, A NEW MINERAL SPEC

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• journal_title：The Canadian Mineralogist
• Contributor：Michael Schindler ; Frank C. Hawthorne ; Danielle M.C. Huminicki ; Patrick Haynes ; Joel D. Grice ; Howard T. Evans ; Jr.
• Publisher：Mineralogical Association of Canada
• Date：2003-
• Format：text/html
• Language：en
• Identifier：10.2113/gscanmin.41.1.83
• journal_abbrev：Can Mineral
• issn：0008-4476
• volume：41
• issue：1
• firstpage：83
• section：Articles

摘要

<p id="p-1">Bobjonesite, Vp>4+p> O (SO₄) (H₂O)₃, is a new mineral species from Temple Mountain, Emery County, Utah, U.S.A. It occurs as blue-green crusts and efflorescences in fractures in a fossil (Triassic) tree; individual crystals are <<1 mm and are intimately intergrown. Bobjonesite hydrates very easily, and is unstable in all but the driest atmosphere. Its structure was determined on a crystal of bobjonesite; however, the physical properties, optical properties and X-ray powder-diffraction pattern were recorded on the synthetic equivalent, and an electron-microprobe analysis was not possible. Bobjonesite has a pale blue streak, a vitreous luster and no observable fluorescence under ultraviolet light. It has no cleavage or parting. The Mohs hardness is ~1, and the calculated density is 2.28 g/cmp>3p>. Bobjonesite is biaxial positive, with α 1.555(2), β 1.561(1), γ 1.574(2), 2m>Vm>(obs.) = 72(1)°, 2m>Vm>(calc.) = 69°; it is non-pleochroic, m>Xm> = m>bm>, m>Ym> ≈ m>am>, m>Zm> ∧ m>cm> ≈ 19° (in β obtuse). Bobjonesite is monoclinic, space group m>Pm>2₁/m>nm>, cell dimensions from single-crystal data: m>am> 7.3940(5), m>bm> 7.4111(3), m>cm> 12.0597(9) Å, β 106.55(1)°, m>Vm> 633.5(1) Åp>3p>, m>Zm> = 4. The strongest seven lines in the X-ray powder-diffraction pattern [m>dm> in Å(m>Im>)(m>hklm>)] are as follows: 5.795(100)(002), 3.498(90)(112), 3.881(48)(1̅03), 5.408(37) (101), 4.571(20)(012), 6.962(11)(1̅01) and 6.254(11)(011). The chemical formula was derived from crystal-structure analysis; the end-member formula is V O (SO₄) (H₂O)₃. The crystal structure of bobjonesite was refined to an m>Rm> index of 3.6% for 1105 observed (| m>Fm>_o | > 5>m>Fm>) reflections measured with an automated four-circle X-ray diffractometer using Mom>Km>α X-radiation. There is one m>Vm> site occupied by Vp>4+p> and surrounded by three O atoms and three (H₂O) groups in an octahedral arrangement, with one short vanadyl bond (1.577 Å), four similar equatorial bonds (<2.022 Å>), and one longer V–O bond (2.278 Å) m>transm> to the vanadyl bond. The structure consists of isolated [Vp>4+p>₂ O₂ (H₂O)₆ (SO₄)₂] clusters linked by hydrogen bonds. p>