polybasite

{{Infobox mineral

| name = Polybasite

| boxwidth =

| boxbgcolor =

| image = Polybasite-37890.jpg

| imagesize =

| alt =

| caption =

| category = Sulfosalt minerals

| formula = {{chem2|[(Ag,Cu)6(Sb,As)2S7][Ag9CuS4]}}

| IMAsymbol = Plb{{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}}

| molweight =

| strunz = 2.GB.15

| dana =

| system = Monoclinic and trigonal polytypes

| class = Prismatic (2/m)
(same H-M symbol)

| symmetry = C2/c

| unit cell =

| color =

| colour = steel black

| habit =

| twinning =

| cleavage = poor on (001)

| fracture = uneven

| tenacity =

| mohs = 1.5–2

| lustre = metallic, adamantine or glimmering

| streak = black with reddish tint

| diaphaneity =

| gravity = 6–6.2

| density =

| polish =

| opticalprop =

| refractive =

| birefringence =

| pleochroism =

| 2V =

| dispersion =

| extinction =

| length fast/slow =

| fluorescence =

| absorption =

| melt =

| fusibility =

| diagnostic =

| solubility =

| impurities =

| alteration =

| other =

| prop1 =

| prop1text =

| references = [http://www.mindat.org/min-3256.html Polybasite: mindat.org][http://www.webmineral.com/data/Polybasite.shtml Webmineral.com]{{Cite web |url=http://www.handbookofmineralogy.com/pdfs/polybasite.pdf |title=Handbook of Mineralogy |access-date=2011-05-16 |archive-date=2016-03-03 |archive-url=https://web.archive.org/web/20160303171441/http://www.handbookofmineralogy.com/pdfs/polybasite.pdf |url-status=dead }}{{cite book|title=Minerals of the World|year=1990|isbn=0-517-68030-0|author=Rudolf Dǔd'a and Luboš Rejl|publisher=Arch Cape Press|page=40}}

}}

Polybasite is a sulfosalt mineral of silver, copper, antimony and arsenic. Its chemical formula is {{chem2|[(Ag,Cu)6(Sb,As)2S7][Ag9CuS4]}}.

It forms black monoclinic crystals (thin, tabular, with six corners) which can show dark red internal reflections. It has a Mohs hardness of 2.5 to 3. It is found worldwide and is an ore of silver. The name comes from the number of base metals in the mineral.