Orthowalpurgite
Orthowalpurgite is an IMA-recognized mineral species in the arsenate class, with the chemical formula (UO₂)Bi₄O₄(AsO₄)₂·2H₂O.
It crystallizes in the orthorhombic crystal system (space group Pbcm).
Key properties: Mohs hardness 4.5; specific gravity 6.51; Pale yellow streak; Adamantine luster; optically biaxial.
IMA symbol Owal, IMA status: approved, named in 1994.
A very rare mineral, probably formed by weathering of an earlier bismuth-bearing sulfide.
It is found associated with Preisingerite, anatase, quartz.
As an orthorhombic dimorph of walpurgite.
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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