Fenaksite
Fenaksite is an IMA-recognized mineral species in the silicate class, with the chemical formula KNaFe²⁺Si₄O₁₀.
It crystallizes in the triclinic crystal system (space group P-1). It is a member of the Litidionite structural group.
Key properties: Mohs hardness 5–5.5; specific gravity 2.744; Pearly on cleavages luster; optically biaxial.
IMA symbol Fnk, IMA status: approved, named in 1959.
Found in pegmatites in association with an ijolite-urtite intrusion in a differentiated alkalic massif.
It is found associated with Albite, nepheline, \aegirine-augite, " delhayelite, eudialyte.
The name refers to Fe, Na, K, Si in the composition.
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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