Natrowalentaite
Natrowalentaite is an IMA-recognized mineral species in the phosphate class, with the chemical formula [Fe³⁺₀.₅Na₀.₅(H₂O)₆][NaAs³⁺₂(Fe³⁺₂.₃₃W⁶⁺₀.₆₇)(PO₄)₂O₇].
It crystallizes in the orthorhombic crystal system (space group Imma). It is a member of the Walentaite structural group.
Key properties: specific gravity 2.91; [Vitreous.] luster; optically biaxial.
IMA symbol Nwal, IMA status: approved, named in 2018.
On fracture surfaces in iron-stained heavily weathered rock as a product of supergene alteration of primary sulfide and arsenide minerals.
It is found associated with Natropharmacosiderite, jarosite.
The prefix, natro, indicates dominant sodium replacing calcium in walentaite.
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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