Zvěstovite-(Fe), Ag6(Ag4Fe2)As4S13, a new member of the tetrahedrite group from the Ulatayskoe Ag–Cu–Co occurrence, eastern Siberia, Russia

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216224%3A14310%2F24%3A00136717" target="_blank" >RIV/00216224:14310/24:00136717 - isvavai.cz</a>

Result on the web

<a href="https://ejm.copernicus.org/articles/36/529/2024/" target="_blank" >https://ejm.copernicus.org/articles/36/529/2024/</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.5194/ejm-36-529-2024" target="_blank" >10.5194/ejm-36-529-2024</a>

Result language

angličtina

Original language name

Zvěstovite-(Fe), Ag6(Ag4Fe2)As4S13, a new member of the tetrahedrite group from the Ulatayskoe Ag–Cu–Co occurrence, eastern Siberia, Russia

Original language description

The new mineral zvěstovite-(Fe), ideally Ag6(Ag4Fe2)As4S13, has been found in the small abandoned Ulatayskoe Ag–Cu–Co occurrence, Ovyurskiy District, Tuva Republic, eastern Siberia, Russia. It occurs as anhedral grains, up to 1 × 0.4 mm in size but usually much smaller, closely intergrown with native silver, in Mg-bearing siderite–quartz gangue. Other associated minerals include acanthite, cobaltite, As-rich members of the tetrahedrite group (kenoargentotennantite-(Fe), tennantite-(Zn), zvěstovite-(Zn)), gersdorffite, jalpaite, krutovite, löllingite, pearceite, safflorite, skutterudite, Br-bearing chlorargyrite, malachite, and muscovite. Zvěstovite-(Fe) is iron black and opaque and has a black streak and metallic lustre. It is brittle and has a conchoidal fracture. No cleavage or parting is observed. The Vickers micro-indentation hardness (Vickers hardness number, VHN; 25 g load) is 169 kg mm−2 (range of 149–187 kg mm−2, n=4), corresponding to a Mohs hardness of 3–3.5. The calculated density is 4.979 g cm−3. In reflected light, zvěstovite-(Fe) is light grey with a greenish tint and isotropic. Internal reflections are ubiquitous and deep red in colour. The reflectance values for wavelengths recommended by the Commission on Ore Mineralogy of the International Mineralogical Association are (R, %): 32.5 (470 nm), 31.1 (546 nm), 30.1 (589 nm), and 28.8 (650 nm). The chemical composition (wt %, electron microprobe data, mean of eight spot analyses) is as follows: Cu 1.81, Ag 56.02, Fe 4.60, Zn 0.01, As 13.85, Sb 2.63, S 21.50, total 100.42. The empirical formula, calculated on the basis of 16 atoms per formula unit, is Ag9.93Cu0.54Fe1.58As3.54Sb0.41S12.83. Zvěstovite-(Fe) is cubic and has a space group of 3m, with a=10.8601(3), V=1280.86(11) Å3, and Z=2. The strongest lines of the X-ray powder diffraction pattern (d, Å (I, %) hkl) are 7.68 (11) 110, 3.136 (100) 222, 2.717 (12) 400, 1.984 (8) 521, 1.921 (23) 440, and 1.638 (11) 622. The crystal structure of zvěstovite-(Fe) was refined to R1=0.0551 for 400 unique reflections with Fo&gt;4σ (Fo). The possible ordering of the split M(2) sites is discussed. The new mineral is the Fe isotype of zvěstovite-(Zn). Both these minerals form the zvěstovite series within the tetrahedrite group.

Czech name

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Czech description

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Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

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OECD FORD branch

10504 - Mineralogy

Project

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Continuities

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year

2024

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Name of the periodical

European Journal of Mineralogy

ISSN

0935-1221

e-ISSN

1617-4011

Volume of the periodical

36

Issue of the periodical within the volume

3

Country of publishing house

DE - GERMANY

Number of pages

12

Pages from-to

529-540

UT code for WoS article

001274007200001

EID of the result in the Scopus database

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