May 20 2014
Burgessite was named after David Burgess (1951-) of Newington in Connecticut, USA, who was a prolific mineral species collector.
Properties of Burgessite
The following are the key properties of burgessite :
- Cell Data
- Space group: P21/n
- a = 4.7058(12)
- c = 9.299(3)
- c = 12.738(4)
- β = 98.933(8)°
- Z = 2
- Crystal Data
- Monoclinic
- Point group: 2/m
- Crystals, prismatic, to 0.1mm, forms {011} and {hol} observed
- Typically as rosettes, to 0.8mm
- X-ray powder pattern: 7.446 (100), 6.267 (44), 2.998 (31), 3.725 (29), 3.260 (25), 2.596 (23), 2.970 (21)
- Chemical Composition
| Elements |
Content 1 |
| As2O5 |
47.91 |
| CoO |
27.31 |
| H2O |
22.65 |
| NiO |
3.52 |
| CaO |
0.18 |
| SO3 |
0.13 |
| ZnO |
0.04 |
| P2O5 |
0.03 |
| Total |
101.77 |
- Optical Properties
- Optical Class: Biaxial (+)
- α = 1.596(2) ; β = 1.604(2); γ = 1.628(2)
- 2V(meas.) = 70(2)°
- 2V(calc.) = 61°
- Orientation: X = b; Y ∧ c = 29° (in β obtuse); Z ∧ a = 20° (in β acute)
- Estimated Properties
| Electron density |
Bulk density (electron density) = 2.85 g/cm3
note: Specific gravity of burgessite = 2.94 g/cm3 |
| Photoelectric |
PEBurgessite = 28.90 barns/electron
U=PEBurgessite x ρ electron density = 82.33 barns/cm3 |
| Fermion index |
Fermion index = 0.0005237727
Boson index = 0.9994762273 |
Radioactivity
|
Burgessite is not radioactive
|
How to Identify Burgessite
Burgessite can be identified in the field by its purplish-pink color. Its transparent form has {010} good and {001} fair cleavage. This mineral has an adamantine luster, with pale pink streak. Its fracture is brittle and irregular.
The density of burgessite is 2.93 g/cm3, with a hardness of 3 – approximate to calcite.
Global Distribution
Burgessite is distributed mainly in Canada at the Keeley mine, South Lorraine Township, Timiskaming District, Ontario.
Occurrence of Burgessite and Useful Mineral Association
Burgessite typically occurs in a secondary mineral, along the fractures in the weathering zone of a polymetallic sulfarsenate deposit.
It is often associated with minerals such as skutterudite, bismuth, arsenolite, bismuthoferrite, erythrite, and cobaltite.
References