Next Article in Journal
Mo and Ni Removal from Drinking Water Using Zeolitic Tuff from Jordan
Previous Article in Journal
Selective Flotation of Calcite from Fluorite: A Novel Reagent Schedule
Article Menu

Export Article

Open AccessArticle
Minerals 2016, 6(4), 115; doi:10.3390/min6040115

Merelaniite, Mo4Pb4VSbS15, a New Molybdenum-Essential Member of the Cylindrite Group, from the Merelani Tanzanite Deposit, Lelatema Mountains, Manyara Region, Tanzania

1
Department of Physics and the A. E. Seaman Mineral Museum, Michigan Technological University, 1400 Townsend Dr., Houghton, MI 49931-1295, USA
2
Department of Earth Sciences, Natural History Museum, Cromwell Road, London SW7 5BD, UK
3
Dipartimento di Scienze della Terra, Università di Firenze, Via La Pira 4, I-50121 Firenze, Italy
4
Department of Materials Science and Engineering, Michigan Technological University, 1400 Townsend Dr., Houghton, MI 49931-1295, USA
5
Department of Mineral Sciences, National Museum of Natural History, Smithsonian Institution, Washington, DC 20560, USA
6
Department of Core Research Laboratories, Natural History Museum, Cromwell Road, London SW7 5BD, UK
*
Author to whom correspondence should be addressed.
Academic Editor: Thomas N. Kerestedjian
Received: 7 September 2016 / Revised: 19 October 2016 / Accepted: 20 October 2016 / Published: 28 October 2016
View Full-Text   |   Download PDF [41251 KB, uploaded 28 October 2016]   |  

Abstract

Merelaniite is a new mineral from the tanzanite gem mines near Merelani, Lelatema Mountains, Simanjiro District, Manyara Region, Tanzania. It occurs sporadically as metallic dark gray cylindrical whiskers that are typically tens of micrometers in diameter and up to a millimeter long, although a few whiskers up to 12 mm long have been observed. The most commonly associated minerals include zoisite (variety tanzanite), prehnite, stilbite, chabazite, tremolite, diopside, quartz, calcite, graphite, alabandite, and wurtzite. In reflected polarized light, polished sections of merelaniite are gray to white in color, show strong bireflectance and strong anisotropism with pale blue and orange-brown rotation tints. Electron microprobe analysis (n = 13), based on 15 anions per formula unit, gives the formula Mo4.33Pb4.00As0.10V0.86Sb0.43Bi0.33Mn0.05 W0.05Cu0.03(S14.70Se0.30)Σ15, ideally Mo4Pb4VSbS15. An arsenic-rich variety has also been documented. X-ray diffraction, electron diffraction, and high-resolution transmission electron microscopy show that merelaniite is a member of the cylindrite group, with alternating centered pseudo-tetragonal (Q) and pseudo-hexagonal (H) layers with respective PbS and MoS2 structure types. The Q and H layers are both triclinic with space group C1 or C 1 ¯ . The unit cell parameters for the Q layer are: a = 5.929(8) Å; b = 5.961(5) Å; c = 12.03(1) Å; α = 91.33(9); β = 90.88(5); γ = 91.79(4); V = 425(2) Å3; and Z = 4. For the H layer, a = 5.547(9) Å; b = 3.156(4) Å; c = 11.91(1) Å; α = 89.52(9); β = 92.13(5); γ = 90.18(4); V = 208(2) Å3; and Z = 2. Among naturally occurring minerals of the cylindrite homologous series, merelaniite represents the first Mo-essential member and the first case of triangular-prismatic coordination in the H layers. The strongest X-ray powder diffraction lines [d in Å (I/I0)] are 6.14 (30); 5.94 (60); 2.968 (25); 2.965 (100); 2.272 (40); 1.829 (30). The new mineral has been approved by the IMA CNMNC (2016-042) and is named after the locality of its discovery in honor of the local miners. View Full-Text
Keywords: merelaniite; cylindrite group; molybdenum; lead; Merelani tanzanite deposit; Tanzania merelaniite; cylindrite group; molybdenum; lead; Merelani tanzanite deposit; Tanzania
Figures

Figure 1

This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).

Scifeed alert for new publications

Never miss any articles matching your research from any publisher
  • Get alerts for new papers matching your research
  • Find out the new papers from selected authors
  • Updated daily for 49'000+ journals and 6000+ publishers
  • Define your Scifeed now

SciFeed Share & Cite This Article

MDPI and ACS Style

Jaszczak, J.A.; Rumsey, M.S.; Bindi, L.; Hackney, S.A.; Wise, M.A.; Stanley, C.J.; Spratt, J. Merelaniite, Mo4Pb4VSbS15, a New Molybdenum-Essential Member of the Cylindrite Group, from the Merelani Tanzanite Deposit, Lelatema Mountains, Manyara Region, Tanzania. Minerals 2016, 6, 115.

Show more citation formats Show less citations formats

Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Related Articles

Article Metrics

Article Access Statistics

1

Comments

[Return to top]
Minerals EISSN 2075-163X Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top