tetragonal Oxides
Cassiterite
SnO2
Crystal Structure
#! Species: Cassiterite
#! System: Tetragonal (4/mmm)
#! Habit: Short prismatic with dominant dipyramid
tetragonal[4/mmm]:{100}@0.8[striation:parallel] + {101}@1.0 + {111}@0.4
tetragonal
4/mmm
{100} {101} {111}
Quick Facts
Hardness
6.5
Specific Gravity
6.85
Refractive Index
1.997
Optical Character
Uniaxial +
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Open in PlaygroundPhysical Properties
Crystal Systemtetragonal
Hardness (Mohs)6.5
Specific Gravity6.85
CleavagePoor prismatic {100}
FractureSubconchoidal to uneven
LustreAdamantine to vitreous
Optical Properties
Refractive Index1.997
Birefringence0.096-0.098
Optical CharacterUniaxial +
Dispersion0.071
Pleochroismmoderate: Yellow-green / Reddish-brown (Variable; strong in colored material, absent in colorless; dichroic)
Colours
BrownBlackReddish-brownYellowColourless (rare - gem quality)
Localities
BoliviaChina (Yunling, Yunnan)IndonesiaMalaysiaCornwall (England - historic)Myanmar
Common Inclusions
FracturesTwinningFluid inclusions
Crystal Forms
tetragonal_prismtetragonal_dipyramid
Notes
Called Andean diamond in Bolivia; dispersion (0.071) is twice that of diamond; faceted gems are rare collectors items
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Open in PlaygroundRelated Minerals
Other minerals in the tetragonal system
