{{Short description|Sulfosalt mineral}} {{Infobox mineral | name = Argyrodite | category = Sulfide mineral | image = Argyrodite-170093.jpg | caption = | formula = Ag<sub>8</sub>GeS<sub>6</sub> |IMAsymbol=Agy<ref>{{Cite journal|last=Warr|first=L.N.|date=2021|title=IMA–CNMNC approved mineral symbols|journal=Mineralogical Magazine|volume=85|issue=3|pages=291–320|doi=10.1180/mgm.2021.43|bibcode=2021MinM...85..291W|s2cid=235729616|doi-access=free}}</ref> | strunz = 2.BA.35 | system = Orthorhombic | class = Pyramidal (mm2) <br/>H-M symbol: (mm2) | symmetry = ''P''na2<sub>1</sub> | unit cell = a = 15.149, b = 7.476 <br/>c = 10.589&nbsp;[Å]; Z&nbsp;=&nbsp;4 | color = Black, purplish tinge | habit = Pseudo-octahedra or pseudo-cubic, dodecahedra, cubes; radiating crystal aggregates, botryoidal crusts, or massive | twinning = Pseudospinel law {111} penetration twins | cleavage = Absent | fracture = Uneven to conchoidal | mohs = 2.5 | luster = Metallic | refractive = | opticalprop = Weakly anisotropic | birefringence = | pleochroism = Weak | streak = | gravity = 6.2-6.5 | density = | melt = | fusibility = | diagnostic = | solubility = | diaphaneity = Opaque | references = <ref name=HBM>[http://rruff.geo.arizona.edu/doclib/hom/argyrodite.pdf Handbook of Mineralogy]</ref><ref name=Mindat>[http://www.mindat.org/min-331.html Mindat.org]</ref> }}

'''Argyrodite''' is an uncommon silver germanium sulfide mineral with formula Ag<sub>8</sub>GeS<sub>6</sub>. The color is iron-black with a purplish tinge, and the luster metallic.

Discovered and named by Albin Weisbach in 1886,<ref>{{Cite journal |last=Weisbach |first=Albin |date=1886 |title=Argyrodit, ein neues Silbererz |url=https://www.biodiversitylibrary.org/item/151080#page/109/mode/1up |journal=Neues Jahrbuch für Geologie und Paläontologie |volume=2 |pages=67}}</ref> it is of interest as it was the material from which Clemens Winkler isolated the element germanium, 15 years after it had been postulated by Mendeleev. It was first described for an occurrence in the Himmelsfürst Mine, Ore Mountains, Freiberg, Saxony, Germany.<ref name=Mindat/>

The Freiberg mineral had previously been imperfectly described by August Breithaupt under the name "Plusinglanz", and Bolivian crystals were incorrectly described in 1849 as crystallized brongniardite.{{sfn|Spencer|1911|p=488}}

Isomorphous with argyrodite is the corresponding tin bearing mineral Ag<sub>8</sub>SnS<sub>6</sub>, also found in Bolivia as pseudocubic crystals, and known by the name canfieldite.{{sfn|Spencer|1911|p=488}} There is also a related mineral, putzite, with composition (Cu<sub>4.7</sub>Ag<sub>3.3</sub>)GeS<sub>6</sub>.

Argyrodite gets its name from the Greek words that loosely translate into "rich in silver".<ref name=HBM/>

== Argyrodite-type material == The term argyrodite is also used for other materials with a similar crystal structure, in particular lithium based argyrodite-type materials, which have received interest from researchers as a potential solid-state electrolyte for lithium-ion batteries.<ref name="Raghavan-2021">{{Cite book|last1=Raghavan|first1=Prasanth|url=https://books.google.com/books?id=wPwgEAAAQBAJ&dq=argyrodite+electrolyte&pg=PA36|title=Ceramic and Specialty Electrolytes for Energy Storage Devices|last2=Fatima|first2=Jabeen|date=2021-04-05|publisher=CRC Press|isbn=978-1-000-35180-4}}</ref><ref>{{Cite journal|last1=Brinek|first1=Marina|last2=Hiebl|first2=Caroline|last3=Wilkening|first3=H. Martin R.|date=2020-06-09|title=Understanding the Origin of Enhanced Li-Ion Transport in Nanocrystalline Argyrodite-Type Li6PS5I|journal=Chemistry of Materials|volume=32|issue=11|pages=4754–4766|doi=10.1021/acs.chemmater.0c01367|issn=0897-4756|pmc=7304077|pmid=32565618}}</ref>

They are considered to be of the form:

{{Chem|Li|7-x|B||Ch|6-x|X|x}}

With x between 0 and 1, B denoting either phosphorus or arsenic, Ch for sulfur or selenium and X for chlorine, bromine or iodine.<ref name="Raghavan-2021" /> However, other forms exist and can be grouped into three main categories, halogen-based argyrodites, halogen-based argyrodites doped with additional semi-metal or metal components and halogen-free argyrodites based on Li, P, S along with a semi-metal.<ref>{{Cite journal |last1=Lu |first1=Xin |last2=Tsai |first2=Chih-Long |last3=Yu |first3=Shicheng |last4=He |first4=Hongying |last5=Camara |first5=Osmane |last6=Tempel |first6=Hermann |last7=Liu |first7=Zigeng |last8=Windmüller |first8=Anna |last9=Alekseev |first9=Evgeny V. |last10=Köcher |first10=Simone |last11=Basak |first11=Shibabrata |last12=Lu |first12=Li |last13=Eichel |first13=Rüdiger A. |last14=Kungl |first14=Hans |date=2022 |title=Lithium phosphosulfide electrolytes for solid-state batteries: Part II |url=https://www.worldscientific.com/doi/10.1142/S1793604722400021 |journal=Functional Materials Letters |volume=15 |issue=7n08 |pages=2240002 |doi=10.1142/S1793604722400021 |issn=1793-6047|url-access=subscription }}</ref>

== References == {{Reflist}}

'''Attribution:''' *{{EB1911|first=Leonard James |last=Spencer |authorlink=Leonard James Spencer |wstitle=Argyrodite |volume=2 |page=488}}

Category:Silver minerals Category:Sulfide minerals Category:Germanium minerals Category:Orthorhombic minerals Category:Minerals in space group 33 Category:Glances