MELANOTEKITE

    Class : Silicates
    Subclass : Sorosilicates
    Crystal system : Orthorhombic
    Chemistry : Pb2Fe2O2Si2O7
    Rarity : Rare

Melanotekite is a rare lead and iron silicate present as a very accessory mineral in metamorphic manganese deposits and lead hydrothermal deposits. It forms a series with kentrolite, its manganiferous equivalent. Its name comes from the Greek melanos (black) and têktos (melted) to emphasize the fact that the mineral heated with a blowtorch melts, forming a blackish mass. Melanotekite is a black to blackish gray and blackish green mineral, which gives small spherules or irregular masses, rarely small pointed crystals.

Main photo : Melanotekite from Tsumeb, Namibia © Carsten Slotta

Melanotekite in the World

The best specimens come from Swedish manganese mines, notably Langban where a mass of more than a ton of melanotekite associated with native lead was extracted, and from Harstig, where melanotekite was relatively common. Good samples with small crystals are known from Hillsboro (New Mexico) and Tsumeb (Namibia). Melanotekite is also reported in Arizona, notably at the Mammoth-St-Anthony mine, and in several lead veins in England, notably Shepton Malley.

Right photo : Melanotekite and willémite from Su Elzu, Ozieri, Sardinia, Italy © Jean-Vincent Coureau

Melanotekite in France

Melanotekite is not present in the French underground.

Twinning

No twin known for this mineral species.

Fakes and treatments

No fakes recorded for this mineral species.


Hardness : 6.5
Density : 5.73 to 6.28
Fracture : Undetermined
Streak : Grey-black

TP : Translucent to opaque
RI : 2.120 to 2.310
Birefringence : 0.190
Optical character : Biaxial +
Pleochroism : Visible
Fluorescence : None

Solubility : Nitric acid

Magnetism : NoneRadioactivity : None