eskebornite
{{Infobox mineral|name=Eskebornite|boxwidth=|boxbgcolor=|image=|imagesize=|alt=|caption=|category=:Category:Selenide minerals|formula=CuFeSe2|molweight=| IMAsymbol = Ebn{{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}}|strunz=2.CB.10a|dana=2.9.1.2|system=|class=Tetragonal|symmetry=|unit cell=|color=Brassy yellow|colour=|habit=Thick tabular crystals, massive|twinning=|cleavage={001} perfect|fracture=|tenacity=|mohs=3–3.5|luster=Metallic|streak=Black|diaphaneity=Opaque|gravity=|density=5.35 (measured) 5.44 (calculated)|polish=|opticalprop=|refractive=|birefringence=|pleochroism=Creamy yellow to yellowish brown|2V=|dispersion=|extinction=|length fast/slow=|fluorescence=None|absorption=|melt=|fusibility=|diagnostic=|solubility=Insoluble|impurities=Ag, S|alteration=|other=Distinctly magnetic|prop1=|prop1text=|references={{ref|1}}{{ref|2}}{{ref|3}}{{ref|5}}}}
Eskebornite is a selenide mineral with the formula CuFeSe2.{{Cite web|url=http://www.mindat.org/min-1409.html|title=Eskebornite: Eskebornite mineral information and data.|website=www.mindat.org|access-date=2016-10-24}}{{Cite web|url=http://webmineral.com/data/Eskebornite.shtml#.WA3FdOh9600|title=Eskebornite Mineral Data|last=Barthelmy|first=Dave|website=webmineral.com|access-date=2016-10-24}} It crystallizes in the tetragonal system and it has a brassy colour. Eskebornite is sometimes found as thick tabular crystals, but is more often found intergrown with other selenides.{{Cite web|url=http://www.handbookofmineralogy.org/pdfs/eskebornite.pdf|title=Handbook of Mineralogy, Eskebornite|last=|first=|date=|website=|publisher=|access-date=}} It is part of the chalcopyrite group and forms a series with chalcopyrite.{{Cite web|url=http://www.mindat.org/min-8734.html|title=Chalcopyrite-Eskebornite Series: Chalcopyrite-Eskebornite Series mineral information and data.|website=www.mindat.org|access-date=2016-10-24}}
Occurrence
Eskebornite was first identified in 1949 by Paul Ramdohr in the Eskaborn Adit, Tilkerode (Abberode), Harz, Saxony-Anhalt, Germany,{{Cite journal|last=D.C. Harris, E.A.J. Burke|title=Eskebornite, two Canadian occurrences|url=http://rruff.info/uploads/CM10_787.pdf|journal=The Canadian Mineralogist|volume=10|pages=786–796}} which it was also named after. It is often found with other selenides, including clausthalite, tiemannite, berzelianite, naumannite, umangite, geffroyite, and chaméanite, but also with other minerals like chalcopyrite, uraninite, ankerite, and dolomite.