KENTROLITE

    Class : Silicates
    Subclass : Sorosilicates
    Crystal system : Orthorhombic
    Chemistry : Pb2Mn2O2Si2O7
    Rarity : Rare

Kentrolite is a rare lead and manganese silicate present as a very accessory mineral in metamorphic manganese deposits. It forms a series with melanotekite, its iron-bearing equivalent. Its name comes from the Greek kentron (point, thorn) because its prismatic crystals form thorny agglomerates. Kentrolite is a very dark reddish-brown mineral, almost black, which produces small, short prismatic crystals often grouped in sheaves.

Main photo : Kentrolite from Big Chief Mine, New-Mexico, USA © Jerry Cone

Kentrolite in the World

The best specimens of kentrolite come from the Swedish manganese mines, notably Langban and Harstig, the South African Wessel mine near Hotazel, and the large zinc-manganese deposit at Franklin (New Jersey) where kentrolite accompanies calcite and willemite. Kentrolite is also known as veinlets crisscrossing franklinite in the large stratiform manganese deposit of Ushkatyn (Kazakhstan).

Kentrolite in France

In France, kentrolite is known in Peyrebrune (Tarn).

Twinning

No twin known for this mineral species.

Fakes and treatments

No fakes recorded for this mineral species.


Hardness : 5
Density : 6.26
Fracture : Irregular
Streak : Brown

TP : Translucent
RI : 2.100 à 2.310
Birefringence : 0.210
Optical character : Biaxial +
Pleochroism : Strong
Fluorescence : None

Solubility : Hydrochloric acid

Magnetism : NoneRadioactivity : None