Field of view 4 mm. From: Shirley Ann group, Big Dodd Spring, Ubehebe Mining District, Cottonwood Mountains, Panamint Mts, Inyo Co., California, USA. — Photo: Leon Hupperichs · CC BY-SA 3.0
Ferrisurite
Ferrisurite is an IMA-recognized mineral species in the silicate class, with the chemical formula Pb₂.₄Fe³⁺₂Si₄O₁₀(CO₃)₁.₇(OH)₃·nH₂O.
It crystallizes in the monoclinic crystal system.
Key properties: Mohs hardness 2–2.5; specific gravity 4; Greenish yellow to olive-green streak; Silky luster; optically biaxial.
IMA symbol Fsur, IMA status: approved, named in 1990.
Found in an oxidized lead deposit in contact metamorphosed impure limestone, as an oxidation product of silicates proximate to galena.
It is found associated with Galena, pyrite, chalcopyrite, covellite, chalcocite, quartz, calcite, hematite, cerussite, mimetite, wulfenite, malachite.
The name refers to a predominance of Fe3+ over Al and its relation to surite.