Jun 11 2014
Bobierrite was named after Pierre Adolphe Bobierre (1823–1881), a French agricultural chemist, who first described the mineral.
Properties of Bobierrite
The following are the key properties of bobierrite:
- Cell Data
- Space group: C2/c
- a = 4.667(1)
- b = 27.926(8)
- c = 10.067(3)
- β = 105.01(2)°
- Z = 4
- Crystal Data
- Monoclinic
- Point group: 2/m
- Crystals are usually acicular, fibrous, and lath-shaped, elongated || [001] and flattened on {010} may be diamond-shaped, to 4cm
- As crystalline aggregates, typically in the form of fans and rosettes, fine-grained, massive
- X-ray powder pattern: 6.96 (100), 2.94 (27), 8.04 (18), 2.81 (13), 2.41 (12), 3.02 (10), 2.13 (10)
- Chemical Composition
| Elements |
Content 1 |
Content 2 |
Content 3 |
| H2O |
35.38 |
34.27 |
35.41 |
| P2O5 |
34.59 |
34.52 |
34.88 |
| MgO |
29.97 |
25.12 |
29.71 |
| CaO |
- |
5.71 |
- |
| Total |
99.94 |
99.62 |
100.00 |
- Optical Properties
- Optical class: Biaxial (+)
- Orientation: Y = b; Z ^ c = 27°- 29°
- Dispersion: r < v, weak
- α = 1.508–1.512; β = 1.514–1.520; γ = 1.541–1.543
- 2V(meas.) = 71(3)°
- 2V(calc.) = 73°
- Estimated Properties
| Electron density |
Bulk density (electron density) = 2.27 g/cm3
note: Specific gravity of bobierrite = 2.20 g/cm3 |
| Photoelectric |
PEBobierrite = 1.21 barns/electron
U = PEBobierrite x ρ electron density = 2.75 barns/cm3 |
| Fermion index |
Fermion index = 0.01
Boson index = 0.99 |
Radioactivity
|
Bobierrite is not radioactive
|
How to Identify Bobierrite
Bobierrite can be identified in the field by its color variations, such as gray and white. It is sometimes colorless. Its transparent form has {010} perfect cleavage. This mineral has a vitreous luster, with white streak.
The density of bobierrite is 2.195 g/cm3, with a hardness of 2 to 2.5 - between gypsum and finger nail.
Global Distribution
Bobierrite is distributed in the following places:
- Chile - Found on Mejillones Island
- Australia - Western Australia in the Pilbara district at Wodgina
- New Zealand - From Marlborough
- USA - Found near Edgerton, Pipestone Co. Minnesota
- Norway - At the Odegarden apatite mines, Bamble
- Portugal - In the Bendada pegmatite, near Guarda
- Russia - Fine large crystals found in the Zheleznyi iron mine, Kovdor massif, Kola Peninsula
- Kenya - Occurs in the Imperial Canyon lava tubes, Northern Chyulu Hills
Occurrence of Bobierrite and Useful Mineral Association
Bobierrite occurs in the chemical alteration of guano deposits; and as a rare alteration product of primary phosphate-bearing minerals.
It is often associated with minerals such as hannayite, schertelite, lithiophilite, sicklerite, purpurite, collinsite, apatite, dolomite, and calcite.
References