Английская Википедия:Aguilarite
Шаблон:Infobox mineral Aguilarite is an uncommon sulfosalt mineral with formula Ag4SeS. It was described in 1891 and named for discoverer Ponciano Aguilar.
Description
Aguilarite is bright lead-gray on fresh surfaces but becomes dull iron black when exposed to air.[1] The mineral occurs with massive habit, as elongated pseudododecahedral crystals up to Шаблон:Convert, or as intergrowths with acanthite or naumannite.[2]
Discovery
In the late 19th century, Ponciano Aguilar, superintendent of the San Carlos mine in Guanajuato, Mexico, found several specimens of a mineral thought to be naumannite.[2]Шаблон:Sfn The samples were given to F. A. Genth for identification, who, along with S. L. Penfield, discovered that it was a new mineral. The mineral was described in the American Journal of Science in 1891 and named aguilarite in honor of Ponciano Aguilar.Шаблон:Sfn When the International Mineralogical Association was founded, aguilarite was grandfathered as a valid mineral species.[3]
Occurrence
Aguilarite is uncommon, and forms at relatively low temperatures in hydrothermal deposits rich in silver and selenium but deficient in sulfur.[2] The mineral is known from a number of countries in North and South America, Europe, Asia, and Australasia.[1][2] Aguilarite occurs in association with acanthite, calcite, naumannite, pearceite, proustite, silver, stephanite, and quartz.[2]
Chemistry and structure
In 2013, aguilarite's chemistry and crystal structure were reexamined by Bindi and Pingitore.Шаблон:Sfn The significant reevaluation of aguilarite did not discredit its status as a valid mineral, but it was established as the selenium analogue of acanthite instead of sulfur-rich naumannite.Шаблон:Sfn The sample primarily studied came from the Gem and Mineral Collection of the Department of Geosciences at Princeton University.Шаблон:Sfn
The work of Petruk et al. in 1974 formed the basis of knowledge regarding the silver–sulfur–selenium system for about forty years. They indexed their x-ray diffraction patterns of aguilarite on an orthorhombic cell similar to naumannite.Шаблон:Sfn Bindi and Pingitore determined that aguilarite is, in fact, monoclinic and is isostructural to acanthite and not naumannite.Шаблон:Sfn Bindi and Pingitore believe that Petruk et al. were unable to resolve closely spaced peaks due to low resolution equipment, making aguilarite appear similar to naumannite. Additionally, a number of inconsistencies in unit cell dimensions in the 1974 work show that aguilarite does not have the same structure as naumannite.Шаблон:Sfn
The crystal structure of aguilarite consists of planes nearly parallel to (010) composed of tetrahedrally coordinated nonmetal atoms and AgX3 triangles (where X is a nonmetal). The planes are joined by twofold-coordinated silver atoms.Шаблон:Sfn
Aguilarite is part of the acanthite-like solid solution series Ag2S–Ag2S0.4Se0.6. The mineral comprises the range from 50 atomic percent selenium up to the transition from monoclinic to orthorhombic.Шаблон:Sfn
See also
References
- Bibliography
Further reading
External links
- ↑ 1,0 1,1 Ошибка цитирования Неверный тег
<ref>; для сносокmindatне указан текст - ↑ 2,0 2,1 2,2 2,3 2,4 Шаблон:Cite encyclopedia
- ↑ Шаблон:Cite web
- Английская Википедия
- Monoclinic minerals
- Sulfosalt minerals
- Silver minerals
- Sulfide minerals
- Selenide minerals
- Minerals in space group 14
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