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| Formula | SnO2 |
| | Optic class & sign | Uniaxial positive |
| | Relief | Very high |
| | Refractive indices | no = 1.990 -2.010
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ne = 2.091 -2.100
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| n increases with Fe content |
| | Birefringence (max.) | 0.090 - 0.100 |
| | | Interference colours tend to be obscured by mineral colour |
| | Sign of elongation | Length-slow, l (+) |
| | Interference figure | Basal sections show uniaxial figure with multiple isochromes |
| | Colour / pleochroism | Commonly strongly coloured, typically in shades of brown and yellow, less commonly red or green; may also be nearly colourless; pleochroism weak to strong, E > O |
| | Zoning | Colour zoning may be present; blotchy-irregular and oscillatory zoning is observed |
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| Form | Habit | Stubby tetragonal prisms with pyramidal terminations; acicular; coarse to fine granular masses; aggregates of radiating or parallel-arranged crystals |
| | | Surface | Euhedral to anhedral |
| | Cleavage | Poor |
| | Twinning | {101} simple or multiple twins common, elbow-type, also cyclic or lamellar |
| | Extinction | Straight to traces of prism faces and cleavage in sections ∥ c; inclined to twin planes |
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| Reaction textures | |
| | Alteration / decomposition | Resistant to weathering; cassiterite is itself an alteration product of Sn-bearing sulfides |
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| Occurence | Ign | Felsic plutonic rocks, pegmatites, greisen, rhyolite |
| | | Met | Skarns of metasomatic contact zones |
| | | Sed | Heavy mineral fraction of clastic sediments |
| | | Hyd | High-temperature hydrothermal vein deposits |
| | | Other | |
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| Distinctive properties | Very high relief and birefringence, colour; resembles rutile |
| | Additional comments | May be anomalously biaxial with small 2V |
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