PENFIELDITE

    Class : Halides
    Subclass : Oxychlorides
    Crystal system : Hexagonal
    Chemistry : Pb2Cl3(OH)
    Rarity : Very rare

Penfieldite is an extremely rare lead chloride. The proximity of the sea conditions the genesis of this chlorine-intensive mineral which is generally formed in industrial slag subjected to the action of sea water. More exceptionally, penfieldite is present in the oxidation zone of lead deposits. It was named in honor of Samuel Lewis Penfield, Professor of Mineralogy at Yale University. Penfieldite forms tiny prismatic crystals or pointed pyramids, colorless to white most of the time but faintly tinged with yellow or bluish when they contain impurities (boleite).

Main photo : Penfieldite from Margarita Mine, Sierra Gorda, Chile © Christian Rewitzer

Penfieldite and diaboleite from Margarita Mine, Sierra Gorda, Chile © Joy Desor
Penfieldite from the slag of Baratti Beach, Italy © Marco Bonifazi
Penfieldite from the scoria of Sounion Cove, Laurion, Greece © Gianfranco Ciccolini
Penfieldite from Waitschach slag, Austria © Fritz Schreiber

Penfieldite in the World

Penfieldite is found in the slag geodes of the old Laurion (Greece) and Baratti Beach (Italy) mines, as well as in the oxidation zone of the Sierra Gorda mines (Atacama Desert, Chile).

Penfieldite in France

Penfieldite is not known in the French underground.

Twinning

Several complex twins are known.

Fakes and treatments

No fakes listed for this mineral species.


Hardness : 3 to 4
Density : 5.82 to 6.61
Fracture : Undetermined
Streak : White

TP : Transparent
RI : 2.130 to 2.210
Birefringence : 0.080
Optical character : Uniaxial +
Pleochroism : None
Fluorescence : None

Solubility : Acids, water

Magnetism : NoneRadioactivity : None