Sewardite
A rare calcium-iron arsenate named in 1982 for Zürich geochemist Terry Seward.
Intro adapted from Wikipedia (CC BY-SA).
Sewardite is an IMA-recognized mineral species in the arsenate class, with the chemical formula CaFe³⁺₂(AsO₄)₂(OH)₂.
It crystallizes in the orthorhombic crystal system (space group Cccm). It is a member of the Carminite structural group.
Key properties: Mohs hardness 3.5; specific gravity 4.16; refractive index 1.94.
IMA symbol Sew, IMA status: approved, named in 2001.
Index entry. This entry combines official IMA/RRUFF species data with published physical-property data and a Wikipedia introduction — a full written entry hasn’t been published yet.
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