GRAFTONITE

    Class : Phosphates, arsenates, vanadates
    Subclass : Anhydrous phosphates
    Crystal system : Monoclinic
    Chemistry : (Fe,Mn,Ca)3(PO4)2
    Rarity : Uncommon

Graftonite is a phosphate of granitic pegmatites. Its name comes from its location of discovery : Grafton (New Hampshire, USA). It only exceptionally forms very coarse, chunky prismatic crystals, and is found mainly in cleavable masses, measuring up to one meter, salmon pink to reddish brown in color, tarnishing to dark brown through alteration. It accompanies classic primary phosphates (triphyllite, lithiophyllite, etc...) and easily alters into secondary phosphates (sicklerite, heterosite, ferrisicklerite, etc...).

Main photo : Graftonite from Groton, Grafton County, New Hampshire, USA © Peter Haas

Graftonite in the World

The largest cleavable masses of graftonite extracted, of metric size, come from the Bull Moose mine, near Custer (South Dakota). Other pegmatites from South Dakota (Nickel Plate), Maine (Greenwood) and New Hampshire (Palermo) have yielded decimetric specimens. This mineral is also known in the famous pegmatite of Hagendorf (Bavaria, Germany) and in certain Brazilian pegmatites, notably those of Lavra do Enio (Minas Gerais). It has been found more sporadically in the pegmatites of Morocco (Sidi Bou Othmane) and Italy (Olgiasca).

Graftonite in France

In France, graftonite is reported in the pegmatites of Collioure (Pyrénées-Orientales).

Twinning

No twin known for this mineral species.

Fakes and treatments

No fakes recorded for this mineral species.


Hardness : 5
Density : 3.67 to 3.79
Fracture : Irregular to sub-conchoidal
Streak : White to pale pink

TP : Translucent
RI : 1.695 to 1.736
Birefringence : 0.024 to 0.027
Optical character : Biaxial +
Pleochroism : Low
Fluorescence : None

Solubility : Acids

Magnetism : NoneRadioactivity : None