Jun 4 2014
Barrerite is a member of the zeolite family, and one of the rarest zeolites.
It was named after Richard Maling Barrer, a New Zealand-born British teacher, who studied about the chemistry of zeolites.
Properties of Barrerite
The following are the key properties of Barrerite:
- Cell Data
- Space Group: Amma
- a = 13.643(2)
- b = 18.200(3)
- c = 17.842(2)
- Z = 8
- Crystal Data
- Orthorhombic
- Point Group: 2/m 2/m 2/m
- As well-formed, laminar crystals, to 5mm, with f010g, f011g, and f111g; f001g is common, but of poor quality
- X-ray powder pattern: 9.10 (> 100), 4.054 (100), 3.028 (80), 3.004 (25), 4.659 (20), 2.773 (20), 1.8192 (17)
- Chemical Composition
| Elements |
Content 1 |
| SiO2 |
58.82 |
| H2O |
16.4 |
| Al2O3 |
14.75 |
| Na2O |
5.97 |
| K2O |
1.76 |
| CaO |
1.66 |
| MgO |
0.24 |
| Fe2O3 |
0.04 |
| MnO |
trace |
| SrO |
trace |
| BaO |
trace |
| Total |
99.64 |
- Optical Properties
- Transparent to translucent
- Color: White to slightly pink
- Luster: Vitreous
- Optical Class: Biaxial (-)
- Orientation: X = a; Y = b; Z = c
- α = 1.4791(5)
- β = 1.4851(5)
- γ = 1.4891(5)
- 2V(meas.) = n.d
- 2V(calc.) = 78(8)°
- Estimated Properties
| Electron density |
Bulk density (electron density) = 2.16 g/cm3
note: Specific gravity of Barrerite = 2.13 g/cm3 |
| Photoelectric |
PEBarrerite = 1.61 barns/electron
U = PEBarrerite x ρElectron density = 3.47 barns/cm3 |
| Fermion index |
Fermion index = 0.01
Boson index = 0.99 |
Radioactivity
|
Barrerite is rarely radioactive
|
How to Identify Barrerite
Barrerite is white to pinkish, with a vitreous-glassy luster. It has a transparent to translucent appearance.
It has a Mohs hardness of 3 to 4, and its cleavage is perfect. It has a white streak, and a density of 2.13 g/cm3.
Global Distribution
Barrerite is distributed near Capo Pula, below South E¯sio Tower, Nora, Sardinia, Italy.
Occurrence of Barrerite and Useful Mineral Association
Barrerite occurs on the walls of large fractures in deeply weathered andesitic and rhyolitic lavas.
It is closely associated with Heulandite.
References