• journal_title：Mineralogical Magazine
• Contributor：S. Anashkin ; A. Bovkun ; L. Bindi ; V. Garanin ; Y. Litvin
• Publisher：Mineralogical Society of Great Britain and Ireland
• Date：2013-04-01
• Format：text/html
• Language：en
• Identifier：10.1180/minmag.2013.077.3.06
• journal_abbrev：Mineralogical Magazine
• issn：0026-461X
• volume：77
• issue：3
• firstpage：327
• section：Articles

Kudryavtsevaite, ideally Na₃MgFe³⁺Ti₄O₁₂, is a new mineral from kimberlitic rocks of the Orapa area, Botswana. It occurs as rare prismatic crystals, up to 100 μm across, associated with Mg-rich ilmenite, freudenbergite and ulvöspinel. Kudryavtsevaite is opaque with a vitreous lustre and shows a black streak. It is brittle; the Vickers hardness (VHN₁₀₀) is 901 kg mm⁻² (range: 876–925) (Mohs hardness ~6). In reflected light, kudryavtsevaite is moderately bireflectant and very weakly pleochroic from dark grey to a slightly bluish grey. Under crossed polars, it is very weakly anisotropic with greyish-bluish rotation tints. Internal reflections are absent. Reflectance values (%), R_min and R_max, are: 21.3, 25.4 (471.1 nm), 20.6, 24.1 (548.3 nm), 20.0, 23.5 (586.6 nm) and 19.1, 22.4 (652.3 nm).

Kudryavtsevaite is orthorhombic, space group Pnma, with a = 27.714(1), b = 2.9881(3), c = 11.3564(6) Å, V = 940.5(1) ų, and Z = 4. The crystal structure [R1 = 0.0168 for 819 reflections with I > 2σ(I)] consists of edge-sharing and corner-sharing chains composed of Mg, Fe³⁺ and Ti atoms coordinated by six atoms of oxygen and running along the b axis, with Na filling the tunnels formed by the chains. The eight strongest powder-diffraction lines [d in Å (I/I₀) (hkl)] are: 7.17 (100) (301), 4.84 (70) (302), 2.973 (35) (901), 2.841 (50) (004), 2.706 (50) (902), 2.541 (50) (312), 2.450 (70) (611), and 2.296 (45) (612). The average results of 12 electron microprobe analyses gave (wt.%): Na₂O 16.46(15), CaO 1.01(3), MgO 5.31(5), Fe₂O₃ 22.24(32), Cr₂O₃ 1.05(6), Al₂O₃ 0.03(2), TiO₂ 53.81(50), total 99.91, corresponding to the empirical formula (Na_2.89Ca_0.10)_Σ2.99(Ti_3.67 Mg_0.72Cr_0.08)_Σ5.99O₁₂, or ideally Na₃MgFe³⁺Ti₄O₁₂.

The new mineral has been approved by the IMA-CNMNC and named for Galina Kudryavtseva (1947–2006), a well known Russian mineralogist and founder of the Diamond Mineralogy Laboratory and scientific school for investigation of diamond mineralogy and geochemistry at the Lomonosov State University in Moscow, Russia.