May 13 2014
Bismutite was named in allusion to the bismuth in its composition. It is a bismuth carbonate mineral.
Properties of Bismutite
The following are the key properties of bismutite:
- Cell Data
- Space group: I 4/mmm
- a = 3.867–3.870
- c = 13.686–13.697
- Z = 2
- Crystal Data
- Tetragonal
- Point group: 4/m2/m2/m
- Very rare in platy crystals, to 0.5mm; typically radially fibrous to spheroidal, in crusts and earthy to dense massive aggregates
- X-ray powder pattern: 2.953 (100), 2.737 (41), 3.724 (30), 1.6184 (30b), 2.137 (25), 1.7502 (22b), 1.9354 (20)
- Chemical Composition
| Elements |
Content 1 |
Content 2 |
| Bi2O3 |
91.68 |
91.37 |
| CO2 |
8.29 |
8.63 |
| H2O |
trace |
- |
| Total |
99.97 |
100.00 |
- Optical Properties
- Optical class: Uniaxial; moderate birefringence
- Orientation: Positive elongation, parallel extinction
- n = 2.12–2.30
- Estimated Properties
| Electron density |
Bulk density (electron density) = 5.82 g/cm3
note: Specific gravity of bismutite = 7.00 g/cm3 |
| Photoelectric |
PEBismutite = 1,586.42 barns/electron
U=PEBismutite x ρ electron density= 9,232.90 barns/cm3 |
| Fermion index |
Fermion index =0.0003351921
Boson index = 0.9996648079 |
Radioactivity
|
Bismutite is not radioactive
|
How to Identify Bismutite
Bismutite can be identified in the field by its color variations, such as brown, brownish-yellow, green, gray, and yellow. Its transparent to translucent form has {001} distinct cleavage. This mineral has a vitreous - pearly luster, with gray streak.
The density of bismutite is 7 g/cm3, with a hardness of 4 – approximate to fluorite.
Global Distribution
Bismutite is distributed in the following places:
- Germany - From Ullersreuth, Thuringia; at Schneeberg, Johanngeorgenstadt, and elsewhere in Saxony
- France - At Meymac, Correze
- England - from Wheal Owles, Wheal Coates, the South Crofty mine, the Penberthy Croft mine, and others in Cornwall; at Caldbeck Fells, Cumbria
- Russia - From Beresovsk, near Yekaterinburg (Sverdlovsk), Middle Ural Mountains
- Bolivia - At Tazna, and many other places
- USA – At the Harding mine, Dixon, Taos Co. New Mexico; in the Trout Creek Pass pegmatites, Chaffee Co. Colorado; from the Comstock mine, Dos Cabezos Mountains, Cochise Co. Arizona; at the Mammoth mine, Tintic district, Juab Co. Utah
- Australia - From Kingsgate, New South Wales
Occurrence of Bismutite and Useful Mineral Association
Bismutite occurs as a relatively common alteration product of other bismuth-bearing minerals in hydrothermal mineral deposits, and granite pegmatites.
It is often associated with minerals such as bismuth, bismuthinite, tetradymite, and many other bismuth-bearing minerals.
References