Colourless Znucalite from Příbram, Czech Republic — Photo: Klaproth · CC BY-SA 4.0
Znucalite
A rare white hydrated calcium-zinc uranyl carbonate — radioactive.
Intro adapted from Wikipedia (CC BY-SA).
Znucalite is an IMA-recognized mineral species in the carbonate class, with the chemical formula CaZn₁₁(UO₂)(CO₃)₃(OH)₂₀·4H₂O.
It crystallizes in the orthorhombic crystal system (space group P-1).
Key properties: specific gravity 3.01–3.1; Silky luster; optically biaxial.
IMA symbol Znu, IMA status: approved, named in 1989.
A rare secondary species at carbonate-hosted polymetallic veins, and nearby oxidizing uranium veins; on dump material and coating mine walls, apparently of post-mine origin.
It is found associated with Gypsum, hydrozincite, serpierite, römerite, sphalerite, galena, pyrite, calcite, aragonite (Přı́bram, Czech Republic); adamite, metalodèvite, umohoite.
The name refers to Zn, U, and Ca in the composition.