Emmonsite - Encyclopedia
Class : Oxides and hydroxides
Subclass : Tellurite
Crystal system : Triclinic
Chemistry : Fe2Te3O9 2H2O
Rarity : Very rare
Emmonsite is an extremely rare secondary hydrated iron tellurite of a green-yellow color, known in less than 20 localities in the world. It accompanies gold and different tellurides (altaite, hessite, sylvanite, etc...) in the epithermal gold veins of Colorado (Vulcan), Nevada (Goldfield) and Mexico (Moctezuma). It was named in honor of the geologist and economist Samuel Franklin Emmons. Its crystals are acicular and very rare, emmonsite mainly constitutes microcrystalline masses, fibrous crusts or elongated velvety aggregates.
Main photo : Emmonsite from Moctezuma, Sonora, Mexico © Stephan Wolfsried
Emmonsite in the World
Twinning
Twins can be observed on the microscopic crystals.
Fakes and treatments
No fake listed for this mineral species.
Hardness : 5
Density : 4.52 to 4.55
Fracture : Undetermined
Streak : Green
TP : Translucent
RI : 1.962 to 2.120
Birefringence : 0.138 to 2.120
Optical character : Biaxial -
Pleochroism : Low
Fluorescence : None
Solubility : Nitric acid and hydrochloric acid
Magnetism : None
Radioactivity : None