Matlockite - Encyclopedia
Class : Halides
Subclass : Chlorofluorides
Crystal system : Tetragonal
Chemistry : PbFCl
Rarity : Rare
Matlockite is a secondary chloro-fluoride from the oxidation zone of lead deposits. The necessary supply of chlorine promotes the formation of matlockite in salty, evaporitic or marine environments. It is therefore found in millimeter-sized crystals in seaside slags. It owes its name to where it was discovered : the Bage mine near Matlock (England). Matlockite forms flattened tabular to lamellar crystals, sometimes squat pyramidal, gathered in rosettes, in radiated subparallel or hemispherical aggregates. It is colorless or pale yellow to yellow-orange, sometimes orange-brown.
Main photo : Matlockite from Cromford, Derbyshire, England © Ru Smith
Matlockite in the World
Twinning
No twin known for this mineral species.
Fakes and treatments
No fakes recorded for this mineral species.
Hardness : 2.5 to 3
Density : 7.12
Fracture : Irregular to sub-conchoidal
Streak : White to gray
TP : Transparent
RI : 2.040 to 2.150
Birefringence : 0.110
Optical character : Uniaxial -
Pleochroism : None
Fluorescence : None
Solubility : Nitric acid
Magnetism : NoneRadioactivity : None