Orange-yellow sharp microcrystals of the extremely rare tellurate mineral leisingite, in a white contrasting matrix. From: Centennial Eureka Mine, Juab County, Utah, United States of America. — Photo: David Hospital · CC BY-SA 4.0
Leisingite
Leisingite is an IMA-recognized mineral species in the oxides & hydroxide class, with the chemical formula Cu₂MgTe⁶⁺O₆·6H₂O.
It crystallizes in the hexagonal crystal system (space group P-31m).
Key properties: Mohs hardness 3–4; specific gravity 3.41; Pale yellow streak; Vitreous, may be satiny or frosted luster; optically uniaxial.
IMA symbol Lei, IMA status: approved, named in 1995.
Found as a very rare secondary mineral in dump material from the oxidized zone of a tellurium-bearing Cu–Au–Ag deposit.
It is found associated with Quartz, jensenite, cesbronite, hematite.
The mineral was named to honor Joseph F. Leising (1949–), Reno, Nevada, USA, geologist and mineral collector, who helped collect the material.