Raygrantite
A lead-zinc sulfate-vanadate from Arizona's Evening Star mine.
Intro adapted from Wikipedia (CC BY-SA).
Raygrantite is an IMA-recognized mineral species in the silicate class, with the chemical formula Pb₁₀Zn(SO₄)₆(SiO₄)₂(OH)₂.
It crystallizes in the triclinic crystal system (space group P-1). It is a member of the Iranite structural group.
Key properties: Mohs hardness 3; specific gravity 6.374; White streak; Vitreous luster; optically biaxial.
IMA symbol Rgr, IMA status: approved, named in 2013.
By alteration of sulfides in a hydrothermal quartz-galena-pyrite-chalcopyrite vein.
It is found associated with Galena, anglesite, cerussite, lanarkite, leadhillite, mattheddleite, alamosite, hydrocerussite, caledonite, diaboleite, fornacite, iranite, phoenicochroite.
The mineral was named to honor Raymond W. Grant, retired professor of geology, Mesa Community College, Arizona, USA.