Gratonite

{{Short description|Sulfosalt mineral}} {{Distinguish|Graftonite}} {{Infobox mineral | name = Gratonite | boxwidth = | boxbgcolor = | image = Gratonite-20896.jpg | imagesize = 260px | alt = | caption = Gratonite, Excelsior Mine, Cerro de Pasco, Peru, the type locality. 1.7 x 1.6 x 1.5 cm. | category = Sulfosalt minerals | formula = Pb₉As₄S₁₅ | IMAsymbol = Gtn<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.JB.55 | dana = | system = Trigonal | class = Ditrigonal pyramidal (3m) <br/><small>(same H-M symbol)</small> | symmetry = ''R3m'' | unit cell = | color = | colour = | habit = | twinning = | cleavage = | fracture = | tenacity = | mohs = | luster = | streak = | diaphaneity = | gravity = | density = | polish = | opticalprop = | refractive = | birefringence = | pleochroism = | 2V = | dispersion = | extinction = | length fast/slow = | fluorescence = | absorption = | melt = | fusibility = | diagnostic = | solubility = | impurities = | alteration = | other = | prop1 = | prop1text = | references = }}

'''Gratonite''' is a lead-arsenic sulfosalt mineral, with the chemical composition Pb₉As₄S₁₅. It is considered a low-temperature dimorph of jordanite. Gratonite was discovered in 1939 at the Excelsior Mine, Cerro de Pasco, Peru. <ref>{{Cite journal |last=Palache, C. and Fisher, D.J. |date=1940 |title=Gratonite - A new mineral from Cerro de Pasco |journal=American Mineralogist|volume=25 |pages=255-265}}</ref> It is named in honor of geologist L. C. Graton (1880–1970), who had a long-standing association with the Cerro de Pasco mines. The other location where it is found is the Rio Tinto mine, Minas de Riotinto (Huelva), Spain. The crystals are very similar to those from Cerro de Pasco.<ref>{{Cite book |last=Calvo Rebollar |first=Miguel |title=Minerales y Minas de España. Vol. II. Sulfuros y sulfosales. |publisher=Museo de Ciencias Naturales de Alava. |year=2003 |isbn=978-84-7821-543-0 |location=Vitoria, Spain |pages=590-591 |language=es |trans-title=Minerals and mines of Spain}}</ref>

==References== {{Reflist}}

==External links== *[http://rruff.geo.arizona.edu/doclib/hom/gratonite.pdf Mineral Data Publishing] *[http://webmineral.com/data/Gratonite.shtml Webmineral] *[http://www.mindat.org/min-1741.html Mindat]

{{Commons}}

Category:Lead minerals Category:Arsenic minerals Category:Sulfide minerals Category:Trigonal minerals Category:Minerals in space group 160

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