Blue crystal agreggates of the very rare tellurite mineral eurekadumpite from the type locality, in a white contrasting matrix. From: Centennial Eureka Mine, Juab County, Utah, United States of America. — Photo: David Hospital · CC BY-SA 4.0
Eurekadumpite
Eurekadumpite is an IMA-recognized mineral species in the arsenate class, with the chemical formula (Cu,Zn)₁₆(Te⁴⁺O₃)₂(AsO₄)₃Cl(OH)₁₈·7H₂O.
It crystallizes in the monoclinic crystal system.
Key properties: Mohs hardness 2.5–3; specific gravity 3.76; Light turquoise streak; Pearly flakes, silky aggregates luster; optically biaxial.
IMA symbol Eur, IMA status: approved, named in 2009.
Found in the oxidation zone of quartz-sulfide ores containing tellurides (mostly hessite) in small cavities and in fractures in quartz.
It is found associated with Mcalpineite, malachite, Zn-bearing olivenite, goethite, unspecified Mn oxides.
Reflects the fact that the first samples were found on the dumps of the Centennial Eureka mine.