White brewsterite-Ba crystals associated to also white wollastonite and prehnite from the TL for the mineral (Gouverneur Talc Company No. 4 Quarry, Diana Township, Lewis County,, New York, United States of America) where it is very rare. Ex Vandenbroucke Museum collection from Waregem, Belgium. — Photo: David Hospital · CC BY 4.0
Brewsterite-Ba
The barium member of the brewsterite zeolite series — brewsterite was reclassified as a series name in 1997, splitting into brewsterite-Sr and brewsterite-Ba.
Intro adapted from Wikipedia (CC BY-SA).
Brewsterite-Ba is an IMA-recognized mineral species in the silicate class, with the chemical formula Ba(Al₂Si₆)O₁₆·5H₂O.
It crystallizes in the monoclinic crystal system (space group P-1). It is a member of the Brewsterite structural group.
Key properties: Mohs hardness 5–5.5; specific gravity 2.45; White streak; Vitreous to pearly on {010} luster; optically biaxial.
IMA symbol Brw-Ba, IMA status: approved, named in 1993.
Hydrothermally deposited in druses lining cavities in basalts and schists; more rarely in ore deposits.
It is found associated with Zeolites, calcite, quartz.
The mineral was named to honor Sir David Brewster (1781–1868), Scottish mineralogist.