Windhoekite
Windhoekite is an IMA-recognized mineral species in the silicate class, with the chemical formula Ca₂Fe³⁺₃₋ₓ[Si₈O₂₀](OH)₄·10H₂O.
It crystallizes in the monoclinic crystal system (space group C2/m). It is a member of the Palygorskite structural group.
Key properties: Mohs hardness 2; specific gravity 2.62; Beige streak; Vitreous or silky luster; optically biaxial.
IMA symbol Whk, IMA status: approved, named in 2010.
Found in miarolitic cavities in alkaline phonolite.
It is found associated with Fluorapophyllite, aegirine, microcline, arisite-(Ce), arisite-(La).
The name refers to Windhoek, the district of Namibia where the studied samples were collected.
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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