FERRISICKLERITE

    Class : Phosphates, arsenates, vanadates
    Subclass : Anhydrous phosphates
    Crystal system : Orthorhombic
    Chemistry : Li(Fe,Mn)PO4
    Rarity : Rare


Ferrisicklerite is the iron-bearing pole of a series that it constitutes with sicklerite ; it has been considered since 2022 as a variety of triphyllite. It is a rare secondary phosphate formed by hydrothermal or meteoritic alteration of primary phosphates (triphyllite, lithiphyllite, etc...) in granitic pegmatites. The crystals are rare, forming individuals of 1 cm maximum, gathered in radiate or spherical aggregates. Ferrisicklerite is generally massive, in nodules or rings of alteration around masses of triphyllite - lithiphyllite. It is yellow-brown to dark brown in color.

Main photo : Ferrisicklerite from Palermo N°1 Mine, New Hampshire, USA © Andrew Hodgson

Ferrisicklerite in the World

Although generally rare, ferrisicklerite is a common mineral in the American phosphate pegmatites of Maine (Rumford, Paris), New Hampshire (Rochester, North Groton), South Dakota (Tip-Top and Keystone). It is also present in lithium pegmatites of California (Pala) and North Carolina (Foote, near Kings Mountain). In Europe, ferrisicklerite constitutes 1 cm crystals in the pegmatite of Hagendorf (Bavaria, Germany), and is found quite frequently in the pegmatites of southern Sweden (Varuträsk, Utö...). Ferrisicklerite is also present in various pegmatites in Africa (Morocco, Namibia, Rwanda, Zimbabwe).

Ferrisicklerite in France

In France, ferrisicklerite is known in the pegmatites of Chanteloube (Haute-Vienne) and Céret (Pyrénées-Orientales).

Twinning

No twin known for this mineral species.

Fakes and treatments

No fakes recorded for this mineral species.



Hardness : 4
Density : 3.2 to 3.4
Fracture : Irregular
Streak : Brown


TP : Opaque
RI : 1.790 to 1.820
Birefringence : 0.021
Optical character : Biaxial -
Pleochroism : Visible
Fluorescence : None


Solubility : Acids


Magnetism : None
Radioactivity : None