Greenockite - Encyclopedia
Class : Sulfides and sulfosalts
Subclass : Sulfides
Crystal system : Hexagonal
Chemistry : CdS
Rarity : Quite common
Greenockite is a relatively common hydrothermal mineral found in zinc-rich, cadmium-bearing hydrothermal veins, as well as in cavities in some basic rocks. It is the most common cadmium mineral. It was named in honor of Charles Murray Cathcart, Lord Greenock, a British Army officer who discovered the mineral. Greenockite generally occurs as lemon-yellow powdery coatings or earthy crusts on sphalerite ; it has an adamantine to resinous luster. The crystals are very rare, hemimorphic pyramidal with conical or tabular endings, they barely exceed 1 cm. It is anecdotally a cadmium ore.
Main photo : Greenockite on calcite from Joplin, Missouri, USA - Smithsonian Institute Collection © Ken Larsen
Greenockite in the World
Twinning
There is a known and rare twinning plane on {11-22}.
Fakes and treatments
No fakes recorded for this mineral species.
Hardness : 3 to 3.5
Density : 4.8 to 4.9
Fracture : Conchoidal
Streak : Yellow
TP : Translucent to transparent
RI : 2.506 to 2.529
Birefringence : 0.023
Optical character : Uniaxial -
Pleochroism : Low
Fluorescence : Yellow
Solubility : Hydrochloric acid
Magnetism : NoneRadioactivity : None