Next Article in Journal
Genesis and Multi-Episodic Alteration of Zircon-Bearing Chromitites from the Ayios Stefanos Mine, Othris Massif, Greece: Assessment of an Unconventional Hypothesis on the Origin of Zircon in Ophiolitic Chromitites
Next Article in Special Issue
Origin of the El Dragón Selenium Mineralization, Quijarro Province, Potosí, Bolivia
Previous Article in Journal
Formation of Carbonate Nanoglobules by a Mixed Natural Culture under Hypersaline Conditions
Article Menu

Export Article

Open AccessArticle
Minerals 2016, 6(4), 123;

Quijarroite, Cu6HgPb2Bi4Se12, a New Selenide from the El Dragόn Mine, Bolivia

Helmholtz Centre Potsdam German Research Centre for Geosciences GFZ, DE-14473 Potsdam, Germany
Dipartimento di Scienze della Terra, Università degli Studi di Firenze, Via G. La Pira 4, I-50121 Firenze, Italy
Eschenweg 6, DE-32760 Detmold, Germany
Department of Earth Sciences, Natural History Museum, Cromwell Road, London SW7 5BD, UK
Author to whom correspondence should be addressed.
Academic Editor: Thomas N. Kerestedjian
Received: 4 October 2016 / Revised: 3 November 2016 / Accepted: 14 November 2016 / Published: 18 November 2016
(This article belongs to the Special Issue Se-Bearing Minerals: Structure, Composition, and Origin)
Full-Text   |   PDF [11955 KB, uploaded 18 November 2016]   |  


Quijarroite, ideally Cu6HgPb2Bi4Se12, is a new selenide species from the El Dragόn mine, Department of Potosí, Bolivia. It most frequently occurs as lath-shaped thin plates (up to 150 µm in length and 20 µm in width) intimately (subparallel) intergrown with hansblockite, forming an angular network-like intersertal texture. Quijarroite is occasionally also present as sub- to anhedral grains up to 200 µm in length and 50 µm in width. It is non-fluorescent, black and opaque with a metallic luster and black streak. It is brittle, with an irregular fracture and no obvious cleavage and parting. In plane-polarized incident light, quijarroite is weakly pleochroic from cream to very slightly more brownish-cream, displaying no internal reflections. Between crossed polars, quijarroite is moderately anisotropic with pale orange-brown to blue rotation tints. Lamellar twinning on {110} is common; parquet twinning occurs rarely. The reflectance values in the air for the COM (Commission on Ore Mineralogy) standard wavelengths (R1 and R2) are: 46.7, 46.8 (470 nm), 47.4, 48.2 (546 nm), 47.1, 48.5 (589 nm), and 46.6, 48.7 (650 nm). Electron-microprobe analyses yielded a mean composition of Cu 13.34, Ag 1.02, Hg 7.67, Pb 16.87, Co 0.03, Ni 0.15, Bi 27.65, Se 33.52, total 100.24 wt %. The mean empirical formula, normalized to 25 apfu (atoms per formula unit), is (Cu5.84Ag0.26)Σ = 6.10(Hg1.06Ni0.07Co0.01)Σ = 1.14Pb2.27Bi3.68Se11.81 (n = 24). The simplified formula is Cu6HgPb2Bi4Se12. Quijarroite is orthorhombic, space group Pmn21, with a = 9.2413(8), b = 9.0206(7), c = 9.6219(8) Å, V = 802.1(1) Å3, Z = 1. The calculated density is 5.771 g·cm−3. The five strongest X-ray powder-diffraction lines (d in Å (I/I0) (hkl)) are: 5.36 (55) (111), 3.785 (60) (211), 3.291 (90) (022), 3.125 (100) (212), and 2.312 (50) (400). The crystal structure of quijarroite can be considered a galena derivative and could be derived from that of bournonite. It is a primary mineral, deposited from an oxidizing low-T hydrothermal fluid at a f S e 2 / f S 2 ratio greater than unity. The new species has been approved by the IMA-CNMNC (2016-052) and is named for the Quijarro Province in Bolivia, in which the El Dragón mine is located. View Full-Text
Keywords: quijarroite; copper; bismuth; lead; mercury; selenium; bournonite structure; El Dragón; Bolivia quijarroite; copper; bismuth; lead; mercury; selenium; bournonite structure; El Dragón; Bolivia

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).

Supplementary material


Share & Cite This Article

MDPI and ACS Style

Förster, H.-J.; Bindi, L.; Grundmann, G.; Stanley, C.J. Quijarroite, Cu6HgPb2Bi4Se12, a New Selenide from the El Dragόn Mine, Bolivia. Minerals 2016, 6, 123.

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



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