Barrerite Locality: Rocky Pass, Kuiu Island , Sitka Borough, Alaska , USA ( Locality at mindat.org ) Barrerite is a rare zeolite species related to stilbite, but found in just a few localities and not nearly as common. This specimen is from a find of the late 90's which really set a new standard for the species. It is, also, an aesthetically attractive specimen in its own right. 4.4 x 3.4 x 3.1 cm — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Barrerite
One of the rarer zeolites — white to pinkish glassy crystals named for New Zealand-born chemist Richard Barrer.
Intro adapted from Wikipedia (CC BY-SA).
Barrerite is an IMA-recognized mineral species in the silicate class, with the chemical formula Na₂(Si₇Al₂)O₁₈·6H₂O.
It crystallizes in the orthorhombic crystal system (space group Amma). It is a member of the Stilbite structural group.
Key properties: Mohs hardness 3.5; specific gravity 2.13; Vitreous luster; refractive index 1.484; optically biaxial.
IMA symbol Bre, IMA status: approved, named in 1974.
On the walls of large fractures in deeply weathered andesitic and rhyolitic lavas.
It is found associated with Heulandite.
The name refers to Richard Maling Barrer (1910{), New Zealand-born British teacher and student of the chemistry of zeolites.