METACINNABAR

    Class : Sulfides and sulfosalts
    Subclass : Sulfides
    Crystal system : Cubic
    Chemistry : HgS
    Rarity : Rare to uncommon

Metacinnabar is the cubic dimorph of cinnabar, much rarer than the latter. It forms a series towards tiemannite, mercury selenide. It is present in low-temperature mercury deposits : these are often sub-surface deposits, satellites of recent volcanic activity. Its name comes from the Greek meta (after) and cinnabar, in allusion to its polymorphism. The metacinnabar usually appears in small grayish-black masses, rarely in small tetrahedra with rough faces. It is an accessory mercury ore.

Main photo : Metacinnabar from Mount Diablo Mine, California, USA © Tony Peterson

Metacinnabar in the World

With the notable exception of Almadén (Spain), metacinnabar is known in most mercury deposits, associated with cinnabar : New Almadén (California) where it constituted a notable part of the ore, New Idria (California), Idrija ( Slovenia), Terlingua (Texas), etc... It is also known in the upper mercury-bearing parts of epithermal gold deposits : Baia Sprie (Romania) and Guadalcazar (San Luis Potosi, Mexico).

Right photo : Metacinnabar of Róka Hill, Budapest, Hungary © Laszlo Toth


Metacinnabar in France

The metacinnabar is not present in the French underground.

Twinning

Twins are known on {111}.

Fakes and treatments

No fakes recorded for this mineral species.


Hardness : 3
Density : 7.65
Fracture : Sub-conchoidal
Streak : Black

TP : Opaque
RI : -
Birefringence : 0
Optical character : None
Pleochroism : None
Fluorescence : None

Solubility : -

Magnetism : NoneRadioactivity : None