Fettelite

{{Infobox mineral | name = Fettelite | category = Sulfosalt mineral | boxwidth = | boxbgcolor = | image = Fettelite-14124.jpg | imagesize = 260px | caption = Cluster of tiny fettelite crystals in a vug from Copiapó, Atacama Region, Chile | formula = Ag¹⁺₁₆Hg²⁺As³⁺₄S^2-₁₅ (rruff) or <br/>[Ag₆As₂S₇][Ag₁₀HgAs₂S₈] (mindat.org) | IMAsymbol = Ftt<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> | molweight = | strunz = 2.LA.30 | system = Monoclinic | class = Sphenoidal (2) <br/><small>(same H-M symbol)</small> | symmetry = ''C2'' | unit cell = a = 15.00, c = 15.46&nbsp;[Å] <br/>V = 3014&nbsp;ų; Z&nbsp;=&nbsp;8 | color = dark violet to red | habit = flakes, hexagonal, micaceous | twinning = intimately twinned with six twin domains | cleavage = perfect | fracture = subconchoidal | tenacity = | mohs = 3.5 | luster = metallic | refractive = N(calc) = 1.74 | opticalprop = Biaxial, anisotrophism weak with strong red internal reflections | birefringence = moderate white to brownish gray | pleochroism = | streak = dark vermillion | gravity = 6.29 | density = | melt = | fusibility = | diagnostic = | solubility = | diaphaneity = subopaque to opaque | other = | references = <ref>[https://www.mineralienatlas.de/lexikon/index.php/MineralData?mineral=Fettelite Mineralienatlas]</ref><ref name=Mindat>[http://www.mindat.org/min-1543.html Mindat.org] Accessed 4 November 2010 </ref><ref name=Jambor>{{Cite journal |last1=Jambor |first1=John L. |last2=Puziewicz |first2=Jacek |last3=Roberts |first3=Andrew C. |year=1997 |title=New mineral name |journal=American Mineralogist |volume=82 |pages=620–624 |url=http://www.minsocam.org/msa/ammin/TOC/abstracts/1997_Abstracts/MJ97_Abstracts/Jambor_p620_97.pdf }}</ref> }} '''Fettelite''', also known as sanguinite, is a mercury-sulfosalt mineral with the chemical formula Ag₁₆HgAs₄S₁₅. The mineral was first described by Wang and Paniagua (1996)<ref>Wang, N. and Paniagua, A. (1996) Fettelite, a new Hg-sulfosalt mineral from Odenwald. Neues Jahrbuch für Mineralogie Monatshefte, 82, 313–320.</ref> who named it after M. Fettel, a German field geologist who collected the first samples from Odenwald.<ref name=Bindi>{{Cite journal |last1=Bindi |first1=Luca |last2=Keutsch |first2=Frank N. |last3=Francis |first3=Carl A. |last4=Menchetti |first4=Silvio |year=2009 |journal=American Mineralogist |title=Fettelite, {Ag₆As₂S₇}{Ag₁₀HgAs₂S₈} from Chañarcillo, Chile: Crystal structure, pseudosymmetry, twinning, and revised chemical formula |volume=94 |pages=609–615 |url=http://www.minsocam.org/msa/ammin/TOC/Abstracts/2009_Abstracts/Apr09_Abstracts/Bindi_p609_09.pdf |doi=10.2138/am.2009.3096|s2cid=53975716 }}</ref> It was first collected in the Nieder-Beerbach mine, 10&nbsp;km south of Darmstadt, Odenwald, Germany. Its normal occurrence is in hydrothermal veins, which can cut gabbro-diorite intrusives. It is closely related to other rare minerals like dervillite, daomanite, vaughanite and criddleite which are also found in the same type locality as fettelite.<ref name=Jambor/>

Fettelite occurs as clusters of hexagonal flakes. These flakes can get up to 0.2 mm across and around 5-10 μm thick. In more complex hexagonal tablets, somewhat larger sub parallel aggregates can be measured.<ref> Mandarino, J.A (1997) Abstracts of new mineral description The Mineralogical Record, 28, 141-143. </ref> The birefringence of Fettelite is moderate white to grayish brown.<ref name=Bindi/>

==References== {{Reflist}}

Category:Arsenic minerals Category:Mercury(II) minerals Category:Silver minerals Category:Sulfosalt minerals Category:Monoclinic minerals Category:Minerals in space group 5 Category:Minerals described in 1996

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