Colourless bladed crystals of rongibbsite. Field of view 4 mm. From: Unnamed prospect, Maricopa Co., Arizona, USA. — Photo: Leon Hupperichs · CC BY-SA 3.0
Rongibbsite
Rongibbsite is an IMA-recognized mineral species in the silicate class, with the chemical formula Pb₂(Si₄Al)O₁₁(OH).
It crystallizes in the monoclinic crystal system (space group C2/m).
Key properties: Mohs hardness 5; specific gravity 4.43; White streak; Vitreous luster; optically biaxial.
IMA symbol Rgb, IMA status: approved, named in 2010.
The product of the weathering of a lead and copper-bearing quartz vein in gneiss.
It is found associated with Wickenburgite, fornacite, mimetite, murdochite, creaseyite.
The mineral was named to honor Ronald Bradford Gibbs, a mineral collector and a mining engineer in Tucson, Arizona, USA, who found the first specimens.