Mineral description : Triphylite

Triphylite from Varuträsk.
Brown on weathered surfaces. Fresh to the left.

Mineral class Phosphates : Amblygonite - Pharmakosiderite group.
Chemical formula Li(Fe,Mn)PO4
Crystal system Orthorombic
Habitus Rarely as crystals and then never well crystallised. Often as cleavable masses.
Cleavage Basally perfect, imperfect in two directions. All cleavages are at right angles to each other.
Hardness 4-5
Density 3.58
Color Pale gray to greenish gray on fresh surfaces.
Streak White to grayish white.
Luster Resinous to vitrous.
Occurance In lithium pegmatites.
Associates Vivianite, ferrisicklerite, heterosite, cleavelandite.
Notes Often with an surfaces of dark blue to black vivianite.
Oxidised triphylite gets a yellow to dark brown surface.
Often with transformation products of ferrisicklerite and heterosite.
Locations A not so common mineral in Sweden, but a few localities exists.
  • Varuträsk, Västerbotten. The most abundant iron phosphate, found in coarse aggregates and nodules.
  • Norrö, Stockholm archipelago.

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Last changed : 1998-08-17