Retzian-(La)
Retzian-(La) is an IMA-recognized mineral species in the arsenate class, with the chemical formula Mn²⁺₂La(AsO₄)(OH)₄.
It crystallizes in the orthorhombic crystal system (space group Pban). It is a member of the Retzian structural group.
Key properties: Mohs hardness 3–4; specific gravity 4.2; Pale brown streak; Vitreous on {010} and fractures, otherwise dull luster; optically biaxial.
IMA symbol Rtz-La, IMA status: approved, named in 1983.
A very rare late phase in fractures in a metamorphosed stratiform zinc orebody.
It is found associated with Willemite, franklinite, calcite, todorokite.
The name refers to its dominant rare earth, lanthanum, and relation to retzian-(Ce).
Index entry. This entry combines official IMA/RRUFF species data with published physical-property data — a full written entry hasn’t been published yet.
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