Patynite, NaKCa<sub>4</sub>[Si<sub>9</sub>O<sub>23</sub>], a New Mineral from the Patynskiy Massif, Southern Siberia, Russia
oleh: Anatoly V. Kasatkin, Fernando Cámara, Nikita V. Chukanov, Radek Škoda, Fabrizio Nestola, Atali A. Agakhanov, Dmitriy I. Belakovskiy, Vladimir S. Lednyov
| Format: | Article |
|---|---|
| Diterbitkan: | MDPI AG 2019-10-01 |
Deskripsi
The new mineral patynite was discovered at the massif of Patyn Mt. (Patynskiy massif), Tashtagolskiy District, Kemerovo (Kemerovskaya) Oblast’, Southern Siberia, Russia. Patynite forms lamellae up to 1 × 0.5 cm and is closely intergrown with charoite, tokkoite, diopside, and graphite. Other associated minerals include monticellite, wollastonite, pectolite, calcite, and orthoclase. Patynite is colorless in individual lamellae to white and white-brownish in aggregates. It has vitreous to silky luster, white streaks, brittle tenacity, and stepped fractures. Its density measured by flotation in Clerici solution is 2.70(2) g/cm<sup>3</sup>; density calculated from the empirical formula is 2.793 g/cm<sup>3</sup>. The Mohs’ hardness is 6. Optically, patynite is biaxial (−) with α = 1.568(2), β = 1.580(2), and γ = 1.582(2) (589 nm). The 2<i>V</i> (measured) = 40(10)° and 2<i>V</i> (calculated) = 44.1°. The Raman and IR spectra shows the absence in the mineral of H<sub>2</sub>O, OH<sup>−</sup>, and CO<sub>3</sub><sup>2−</sup> groups and B−O bonds. The chemical composition is (electron microprobe, wt.%): Na<sub>2</sub>O 3.68, K<sub>2</sub>O 5.62, CaO 26.82, SiO<sub>2</sub> 64.27, total 100.39. The empirical formula based on 23 O <i>apfu</i> is Na<sub>1.00</sub>K<sub>1.00</sub>Ca<sub>4.02</sub>Si<sub>8.99</sub>O<sub>23</sub>. Patynite is triclinic, space group <i>P</i><span style="text-decoration: overline;">1</span>. The unit-cell parameters are: <i>a</i> = 7.27430(10), <i>b</i> = 10.5516(2), <i>c</i> = 13.9851(3) Å, α = 104.203(2)°, β = 104.302(2)°, γ = 92.0280(10)°, <i>V</i> = 1003.07(3) Å<sup>3</sup>, <i>Z</i> = 2. The crystal structure was solved by direct methods and refined to <i>R</i><sub>1</sub> = 0.032. Patynite is an inosilicate with a new type of sextuple branched tubular chain [(Si<sub>9</sub>O<sub>23</sub>)<sup>10−</sup>]<sub>∞</sub> with an internal channel and [(Si<sub>18</sub>O<sub>46</sub>)<sup>20−</sup>] as the repeat unit. The strongest lines of the powder X-ray diffraction pattern [<i>d</i><sub>obs</sub>, Å (<i>I</i>, %) (<i>hkl</i>)] are: 3.454 (100) (2-1-1), 3.262 (66) (2-1-2), 3.103 (64) (02-4), 2.801 (21), 1.820 (28) (40-2). Type material is deposited in the collections of the Fersman Mineralogical Museum of the Russian Academy of Sciences, Moscow, Russia with the registration number 5369/1.