Dadsonite - Encyclopedia

Class : Sulfides and sulfosalts
Subclass : Sulfosalts
Crystal system : Triclinic
Chemistry : Pb₂₃Sb₂₅S₆₀Cl
Rarity : Rare

Dadsonite is a rare sulfosalt of lead and antimony. It forms in hydrothermal veins where it associates with other lead sulfides and sulphosalts (jamesonite, bournonite, boulangerite, chalcostibite, zinkenite, etc...). It was named in honor of the geologist and mineralogist Alexander Stewart Dadson who made important contributions to the mining development of the Yellowknife gold mine (Canada). Dadsonite is opaque and only develops small fibrous or acicular crystals measuring a few millimeters long streaked parallel to the elongation. These crystals are mainly grouped in aggregates resembling "steel wool" with a lead gray color and a metallic luster.

Main photo : Dadsonite from St-Pons, Barcelonnette, Alpes-de-Haute-Provence, France

Dadsonite in the World

Dadsonite is only known from around ten deposits in the world. Among the latter, it is reported in Yelloknife and in Ontario (Canada), but also in Pershing County (Nevada), in Wolfsberg (Germany), in Laurion (Greece), as well as in some roosts in Italy, Spain and Slovakia.

Dadsonite in France

In France, dadsonite is known in decimetric aggregates in St-Pons near Barcelonnette (Alpes-de-Haute-Provence) which constitute the best samples in the world.

Twinning

Many twins are known but not visible to the naked eye.

Fakes and treatments

No fakes listed for this mineral species.

Hardness : 2.5
Density : 5.68
Fracture : Undetermined
Streak : Black

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

Solubility : -

Magnetism : NoneRadioactivity : None