Brewsterite - Encyclopedia
Class : Silicates
Subclass : Tectosilicates
Crystal system : Monoclinic
Chemistry : (Sr,Ba,Ca)Al2Si6O16 5H2O
Rarity : Rare
Brewsterite is a rare zeolite that occupies the cavities of basalts and shales, often in the company of calcite. It is also sometimes a zeolite from hydrothermal veins and exceptionally nepheline syenite. Its name was given to it in honor of the Scottish physicist and mineralogist Sir David Brewster. It occurs in isometric or prismatic crystals, striated and elongated, not exceeding 1.5 cm, often grouped in rosettes or fibroradiated aggregates. It is usually colorless or white, it can sometimes be colored yellowish or greenish.
Main photo : Brewsterite from Whitesmith mine, Strontian, Scotland, UK © John Sobolewski
Brewsterite in the World
Twinning
No twin known for this mineral species.
Fakes and treatments
No fake recorded for this mineral species.
Hardness : 5
Density : 2.5
Fracture : Irregular
Trace : White
TP : Translucent to transparent
RI : 1.512 to 1.530
Birefringence : 0.014
Optical character : Biaxial +
Pleochroism : None
Fluorescence : None
Solubility : Hydrochloric acid
Magnetism : None
Radioactivity : None