Sep 3 2013
Beryllonite was named after the key element in its composition – Beryllium.
Properties of Beryllonite
The following are the key properties of beryllonite:
- Cell Data
- Space group: P21/n
- a = 4.229
- b = 6.931
- c = 7.862
- β = 99.61°
- Z = 4.
- Crystal Data
- Monoclinic, pseudo-orthorhombic
- Point group: 2/m
- Tabular on {010} to short prismatic || [010]
- Crystals may have many forms, especially || [100] and [010]
- Some faces typically etched to dullness, to 25 cm
- Also in spherical aggregates, fibrous, massive
- Twinning: On {101}, contact and penetration twins; on {110} and {100} polysynthetic and pseudohexagonal stellate twins
- X-ray powder pattern: 2.84 (10), 3.65 (9), 2.28 (7), 3.92 (6), 2.37 (6), 4.44 (4), 1.965 (4).
- Chemical Composition
| Elements |
Content 1 |
Content 2 |
| P2O5 |
55.86 |
55.89 |
| Na2O |
23.64 |
24.41 |
| BeO |
19.84 |
19.70 |
| LOI |
0.08 |
- |
| Total |
99.42 |
100.00 |
- Optical Properties
- Optical class: Biaxial (-)
- Orientation: X = b; Y = a; Z = c
- Dispersion: r < v, weak
- α = 1.552; β = 1.558; γ = 1.561
- 2V(meas.) = 67°57’.
- Estimated Properties
| Electron density |
Bulk density (electron density) = 2.76 g/cm3
note: Specific gravity of beryllonite = 2.83 g/cm3 |
| Photoelectric |
PEBeryllonite = 1.52 barns/electron
U=PEBeryllonite x ρ electron density= 4.19 barns/cm3 |
| Fermion index |
Fermion index = 0.07
Boson index = 0.93 |
|
Radioactivity
|
Beryllonite is not radioactive |
How to Identify Beryllonite
Beryllonite can be identified in the field by its color variations such as white and light yellow. This mineral is also sometimes colorless. Its transparent to translucent form has perfect cleavage. This mineral has a vitreous – pearly luster with a white streak. The fracture on this mineral is brittle – conchoidal. The density of beryllonite is 2.8 g/cm3 with a hardness of 5.5-6 - between knife blade and orthoclase. Beryllonite is non-fluorescent.
Global Distribution
Beryllonite is distributed in the following places:
- USA - In Maine, found on Sugarloaf Mountain, near Stoneham, at the Dunton quarry and the Bell Pit, Newry, Oxford Co.
- Canada - Occurs at Mont Saint-Hilaire, Quebec.
- Finland - Found at the Viitaniemi pegmatite, Erajarvi.
- England - In the Meldon aplite, Okehampton, Devonshire.
- Sweden - From the Norro pegmatite, on Rano Island.
- Afghanistan - Large crystals from Paprock, Laghman Province.
- Brazil - Occurs in the Enio pegmatite mine, northeast of Galileia; at the Lavra da Ilha pegmatite, in the Jequitinhonha River, 3 km north of Taquaral; and from the Almerindo mine, Linopolis, Minas Gerais.
Occurrence of Beryllonite and Useful Mineral Association
Beryllonite occurs as a rare secondary mineral in granitic and alkalic pegmatites. It is often associated with minerals such herderite, triplite, beryl, apatite, cassiterite, columbite, eosphorite, pollucite, morinite, lithiophilite, vayrynenite, elbaite, petalite, quartz, lepidolite, albite, orthoclase.
References