Zinkenite - Encyclopedia

Class : Sulphides and sulfosalts
Subclass : Sulfosalts
Crystal system : Hexagonal
Chemistry : Pb₉Sb₂₂S₄₂
Rarity : Uncommon

Zinkenite (or zinckenite) is one of the most common prismatic lead sulfosalts (lead sulfoantimoniides). It owes its name to the German geologist and mineralogist J. K. L. Zinken. It is found, like boulangerite, semseyite, jamesonite or plagionite, in medium-temperature lead-antimony hydrothermal veins. It appears in fibrous aggregates, more rarely in distinct striated crystals parallel to the elongation. Its color is steel gray, becoming iridescent by tarnishing, its luster is metallic. This mineral is easily altered at the outcrop, giving mixtures of antimony oxides and lead oxides ; it is very difficult to distinguish from other fibrous sulfosalts by simple means. It can possibly be used as an ore of antimony, but of mediocre quality.

Zinkenite in the World

The most beautiful crystals of zinkenite come from Wolfsberg (Germany), they can reach 5 cm. It is also found in Itos (Oruro, Bolivia) as well as in Herja Mine (Romania).

Zinkenite in France

In France, the most beautiful specimens come from St-Pons (Alpes-de-Haute-Provence), the crystals are in the form of pluricentimetric rods on calcite and siderite. Specimens are usually acid cleared (pictured right).

Twinning

No known twin for this mineral species.

Fakes and treatments

Most specimens from St-Pons (Alpes-de-Haute-Provence) are cleared with acid.

Hardness : 3 to 3.5
Density : 5.3
Fracture : Irregular
Streak : Gray

TP : Opaque
RI : Not measurable
Birefringence : Not measurable
Optical character : None
Pleochroism : None
Fluorescence : None

Solubility : Hydrochloric acid

Magnetism : None
Radioactivity : None