Cassiterite, a black mineral is a member of rutile group and an important ore of tin. It was named after a Greek word 'kassiteros' which means tin.
Properties of Cassiterite
The following are the key properties of Cassiterite:
- Cell Data
- Space Group: P42/mnm (synthetic)
- a = 4.7382(4)
- c = 3.1871(1)
- Z = 2
- Crystal Data
- Tetragonal
- Point Group: 4/m 2/m 2/m
- Crystals short to long prismatic ‖ [001], with {110} and {100} well developed, terminated by steep pyramidal forms, to 10 cm
- In radially fibrous botryoidal crusts and concretionary masses; coarse to fine granular, massive
- Twinning: Very common on {011}, as contact and penetration twins geniculated, lamellar.
- Chemical Composition
| Elements |
Content 1 |
| SnO2 |
99.26 |
| SiO2 |
0.18 |
| Remainder |
0.22 |
| Total |
99.66 |
- Optical Properties
- Optical Class: Uniaxial (+); anomalously biaxial
- Pleochroism: Strong to very weak; yellow, red, brown
- Absorption: E > O
- ω = 1.990–2.010
- ε = 2.093–2.1
- 2V(meas.) = 0°–38°
- Anisotropism: Strong
- Estimated Properties
| Electron density |
Bulk density (electron density)=6.26 g/cm3
note: Specific gravity of Cassiterite = 7.15 g/cm3 |
| Photoelectric |
PECasseterite = 247.66 barns/electron
U= PECasseterite x ρ electron density = 1550.92 barns/cm3 |
| Fermion index |
Fermion index = 0.13
Boson index = 0.87 |
| Radioactivity |
Cassiterite is not radioactive |
How to Identify Cassiterite
Cassiterite is gray, green, brownish black, brown in color or colorless at times. Its appearance varies from transparent to translucent to opaque. It is non-fluorescent with a brownish white streak and a perfect cleavage. It is present in different forms including prismatic crystals, massive crystal and botryoidal forms. The crystals have irregular fracture patters on its flat surfaces. The relative hardness of the mineral ranges from 6 to 7, and its average density is 6.9 g/cm3.
Global Distribution
Cassiterite is widely distributed in the following locations:
- Saxony, at Marienberg, Altenberg, Johanngeorgenstadt, Germany
- C´inovec (Zinnwald) and Horn´i Slavkov (Schlaggenwald), Czech Republic
- La Villeder, Morbihan, France
- Panasqueira and Cabreiros, Portugal
- Cornwall, from St. Just and Carn Brae to Liskeard, England
- Jos district, Nigeria
- Otjimbojo, Namibia
- Banka and Billiton islands, Indonesia
- Perak and Selangor States, Malaysia
- New England Ranges, at Emmaville and Elsmore, New South Wales, Australia
- Greenbushes and Pilbara, Western Australia
- Mt. Bischoff and Mt. Zeehan, Tasmania
- Xue Bao Diang Mountains, Sichuan Province, China
- Fazenda do Funil, Ferros, Minas Gerais, Brazil
- Araca, Oruro, Potos´i, Huanini, and Llallagua, Bolivia.
Occurrence of Cassiterite and Useful Mineral Association
Cassiterite occurs in granite, rhyolite, granite pegmatite, large alluvial placers, greisen, medium- to high-temperature hydrothermal veins and metamorphic deposits in rare cases. It is often associated with the minerals like tourmaline, wolframite, muscovite, lepidolite, scheelite, fluorite, molybdenite, bismuth, arsenopyrite, quartz and topaz.
References
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