Castellaroite Field of view: 5 mm Locality: Monte Nero Mine, Rocchetta Vara, La Spezia, Liguria, Italy — Photo: Henk Smeets – tomeikminerals.com · CC BY 4.0
Castellaroite
A rare hydrated manganese arsenate related to the phosphate metaswitzerite.
Intro adapted from Wikipedia (CC BY-SA).
Castellaroite is an IMA-recognized mineral species in the arsenate class, with the chemical formula Mn²⁺₃(AsO₄)₂·4.5H₂O.
It crystallizes in the monoclinic crystal system (space group P2_1/n).
Key properties: Mohs hardness 2.5; specific gravity 3.14; White streak; Vitreous to silky luster; optically biaxial.
IMA symbol Ctr, IMA status: approved, named in 2015.
A secondary mineral precipitated from oxidizing hydrothermal fluids.
It is found associated with Coralloite, manganohörnesite, rhodochrosite, sarkinite, sterlinghillite, strashimirite, wallkilldellite (Monte Nero mine); braccoite, hematite.
The mineral was named to honor Fabrizio Castellaro (b. 1970), an Italian mineral collector specializing in the minerals of Liguria, who discovered the first specimens.