Millsite specimen — Photo: Mineralogist · Public Domain
Millsite
Millsite is an IMA-recognized mineral species in the oxides & hydroxide class, with the chemical formula CuTeO₃·2H₂O.
It crystallizes in the monoclinic crystal system (space group P2_1/c).
Key properties: specific gravity 3.963; Pale green streak; Vitreous luster; optically biaxial.
IMA symbol Mls, IMA status: approved, named in 2015.
A secondary mineral found within vugs, interstices and along cracks in granular quartz from a single boulder of quartz-rich granite, probably a glacial erratic. Oxidation of primary sulfides and tellurides under near-surface, wet.
It is found associated with Teineite, malachite, U-rich mcalpineite, schmitterite, a copper sulfate (probably brochantite), goethite, an amorphous Cu-Te-Si gel-like material.
The mineral was named to honor Dr. Stuart J. Mills (b. 1982), currently Senior Curator of Geosciences, Museums Victoria, Melbourne, Australia.