Gachingite, Au(Te1-xSex) 0.2 approximate to x <= 0.5, a new mineral from Maletoyvayam deposit, Kamchatka peninsula, Russia

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216208%3A11310%2F22%3A10448464" target="_blank" >RIV/00216208:11310/22:10448464 - isvavai.cz</a>

Result on the web

<a href="https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=tumipuS3sc" target="_blank" >https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=tumipuS3sc</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1180/mgm.2022.9" target="_blank" >10.1180/mgm.2022.9</a>

Result language

angličtina

Original language name

Gachingite, Au(Te1-xSex) 0.2 approximate to x <= 0.5, a new mineral from Maletoyvayam deposit, Kamchatka peninsula, Russia

Original language description

Gachingite, Au(Te1-xSex), 0.2 approximate to x &lt;= 0.5, is a new mineral discovered in the Gaching ore occurrence of the Maletoyvayam epithermal deposit, Kamchatka, Russia. Gachingite forms individual droplet-like grains of sizes from 2 to 10 mu m included in native gold (Au-Ag), associated with calaverite, maletoyvayamite, watanabeite and Au-Sb oxides. The aggregates do not exceed 100 mu m in diameter. In plane-polarised light, gachingite is grey with a bluish tint, has bireflectance (bluish-grey to deep grey), and strong anisotropy with rotation tints blue to dark blue to brown. Reflectance values for gachingite in air (R-min, R-max in %) are: 39.9, 40.3 at 470 nm; 41.6, 43.3 at 546 nm; 42.0, 43.7 at 589 nm; and 43.0, 44.0 at 650 nm. Eighteen electron-microprobe analyses of gachingite gave an average composition: Au 62.40, Ag 0.57, Se 9.78, Te 27.33 and S 0.01, total 100.09 wt.%, corresponding to the formula (Au0.96Ag0.02)(Sigma 0.98)(Te0.65Se0.37)(Sigma 1.02) based on 2 apfu, the simplified formula is Au(Te0.65Se0.35); the average analyses of its synthetic analogue is Au 65.7, Se 13.1 and Te 21.1, total 99.9 wt.%, corresponding to Au-1.00(Te0.50Se0.50). The calculated density is 10.47 g/cm(3). The mineral is orthorhombic, space group Cmce (#64) with a = 7.5379 angstrom, b = 5.7415 angstrom, c = 8.8985 angstrom, V = 385.12 angstrom(3) and Z = 8. The crystal structure was solved and refined from the single-crystal X-ray-diffraction data of synthetic Au-1.00(Te0.50Se0.50). The crystal structure of gachingite represents a unique structure type, containing linear [Au-Au-Au] chains running along the b-axis indicating strong metallic interaction in one direction. The structural identity of gachingite and its synthetic analogue Au-1.00(Te0.50Se0.50) was confirmed by electron back-scatter diffraction and Raman spectroscopy. The formation of gachingite requires an abundant source of Au and Se and a high oxidising environment. Gachingite is related to the gold-bearing productive stage of ore mineralisation, which is stable at 250 degrees C in logf(Se2) range of -12.4 and -5.7. The mineral is named after its type locality.

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

10505 - Geology

Project

—

Continuities

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year

2022

Confidentiality

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

Name of the periodical

Mineralogical Magazine

ISSN

0026-461X

e-ISSN

1471-8022

Volume of the periodical

86

Issue of the periodical within the volume

2

Country of publishing house

GB - UNITED KINGDOM

Number of pages

9

Pages from-to

205-213

UT code for WoS article

000771958000001

EID of the result in the Scopus database

2-s2.0-85124025025