Adelite - Encyclopedia
Class : Phosphates, arsenates, vanadates
Subclass : Anhydrous arsenates
Crystal System : Orthorhombic
Chemistry : CaMg(AsO4)(OH)
Rarity : Very rare
Adelite is an extremely rare arsenate of some metamorphic manganese-iron or zinc deposits. Its name comes from the Greek adelos (dark) which emphasizes its lack of transparency. It forms small elongated or tabular crystals, and small hemispherical masses, colorless, or of various colors (gray-yellowish to yellow, gray-bluish to gray, pale green, brown...).
Main photo : Pink adelite from Sterling Mine, New Jersey, USA © Chris O'Neill
Adelite in the World
Adelite in France
Adelite is not present in the French subsoil.
Twinning
No twin known for the species.
Fakes and treatments
No known fakes or treatments.
Hardness : 5
Density : 3.71 to 3.76
Fracture : Conchoidal to uneven
Trace : White
TP : Translucent to transparent
RI : 1.712 to 1.731
Birefringence : 0,019
Optical character : Biaxial +
Pleochroism : None
Fluorescence : None
Solubility : Hydrochloric and nitric acids
Magnetism : None
Radioactivity : None