Barrerite

Barrerite is a tectosilicate mineral and a member of the zeolite family. It is one of the rarer zeolites. It was named for Richard Barrer, a New Zealand-born chemist.^[4]

Barrerite
Barrerite from Kuiu Island, Alaska, USA.
General
Category	Tectosilicate minerals, zeolite group, stilbite subgroup
Formula	Na2(Si7Al2)O18·6H2O
IMA symbol	Bre[1]
Strunz classification	9.GE.15
Crystal system	Orthorhombic
Crystal class	Dipyramidal (mmm) H-M symbol: (2/m 2/m 2/m)
Space group	Amma
Identification
Color	White, pink
Cleavage	Perfect
Mohs scale hardness	3 - 4
Luster	Vitreous-glassy
Streak	White
Diaphaneity	Transparent to translucent
Specific gravity	2.13
Optical properties	Biaxial (-)
Refractive index	nα = 1.479 nβ = 1.485 nγ = 1.489
References	[2][3][4]

Barrerite crystal are white to pinkish, with a vitreous-glassy luster. The crystal system is orthorhombic and is flat and tabular in appearance. It has a Mohs hardness of 3 to 4 and its cleavage is perfect. Barrerite has a white streak and a density of 2.13.

It was first described in 1974 for an occurrence in Sardinia at Sant' Efisio Tower on Cape Pula in Cagliari Province.^[4] It has also been reported from Rocky Pass, Kuiu Island, Alaska, and a few other localities.