Heyerdahlite
Heyerdahlite is an IMA-recognized mineral species in the silicate class, with the chemical formula Na₃Mn₇Ti₂(Si₄O₁₂)₂O₂(OH)₄F(H₂O)₂.
It crystallizes in the triclinic crystal system (space group P-1). It is a member of the Astrophyllite structural group.
Key properties: Mohs hardness 3; specific gravity 3.245; Pale brown streak; Vitreous luster; optically biaxial.
IMA symbol Hdh, IMA status: approved, named in 2017.
A late-stage hydrothermal mineral in nepheline-syenite pegmatite hosted by foyaite.
It is found associated with Albite, aegirine, hastingsite/magnesio-hastingsite, kupletskite, lorenzenite, pyrophanite.
The mineral was named to honor the Norwegian explorer Thor Heyerdahl (1914-2002), who was born and raised in the city of Larvik.
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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