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Graftonite
An iron-manganese-calcium phosphate forming translucent brown-to-pink monoclinic crystals in pegmatites.
Intro adapted from Wikipedia (CC BY-SA).
Graftonite is an IMA-recognized mineral species in the phosphate class, with the chemical formula Fe²⁺Fe²⁺₂(PO₄)₂.
It crystallizes in the monoclinic crystal system (space group P2_1/c). It is a member of the Graftonite structural group.
Key properties: Mohs hardness 5; specific gravity 3.67–3.79; White to pale pink streak; Vitreous towards resinous luster; optically biaxial.
IMA symbol Gft, IMA status: approved, named in 1900.
A primary mineral or exsolution product in complex granite pegmatites.
It is found associated with Triphylite, lithiophilite, sarcopside, ferrisicklerite, heterosite, arrojadite, fairfieldite, barbosalite, huréaulite, almandine, zircon, albite, muscovite.
The name refers to its first-noted occurrence near Grafton, New Hampshire, USA.