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
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