NAGYÁGITE

    Class : Sulfides and sulfosalts
    Subclass : Sulfides
    Crystal system : Tetragonal
    Chemistry : (Pb,Sb)2(Au,Te)S2
    Rarity : Rare

Nagyágite is a rare primary metallic mineral from epithermal gold deposits. It is one of the rare gold sulfides, which accompanies telluride deposits (hessite, calaverite, sylvanite), native gold and base metal sulfides in its deposits. Its name comes from its locality of discovery : Nagyág (currently Sacarimb) in Romania. With a metallic luster and a bluish lead gray color, it occurs in granular masses, sometimes in fine striated rectangular tabular crystals, or in leafy, twisted strips with jagged edges. It is a very minor gold ore and a minor tellurium ore.

Main photo : 5 cm nagyágite blades in rhodochrosite from Sacaramb, Romania © Rob Lavinsky

Nagyágite in the World

Only the type locality of Sacarimb (formerly Nagyág) in Romania produced remarkable samples. Nagyágite constituted a notable part of the gold ore there, in free crystals reaching up to 3 cm and in blades reaching 5 cm included in the rhodochrosite. The Romanian Baia-de-Aries deposit as well as the Emperor (Fiji) and Oroya (Kalgoorlie, Australia) mines also provided some good crystallized samples.

Right photo : Nagyágite from Sacaramb, Romania © Stephan Wolfsried

Nagyágite in France

Nagyágite is not present in the French underground.

Twinning

Multiple twins on (001) are common.

Fakes and treatments

No fakes recorded for this mineral species.


Hardness : 1 to 1.5
Density : 7.35 to 7.49
Fracture : Undetermined
Streak : Gray-black

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

Solubility : Nitric acid

Magnetism : NoneRadioactivity : None