tetragonal Nesosilicates
Zircon
Formula ZrSiO4
Crystal Structure
#! Species: Zircon
#! System: Tetragonal (4/mmm)
#! Habit: Tetragonal prism with dipyramid
tetragonal[4/mmm]:{100}@1.0 + {101}@0.8
tetragonal
4/mmm
{100} {101}
Quick Facts
Hardness
7.5
Specific Gravity
4.6
Refractive Index
1.925
Optical Character
Uniaxial +
Physical Properties
- Crystal System
- tetragonal
- Hardness (Mohs)
- 7.5
- Specific Gravity
- 4.6
- Cleavage
- Imperfect
- Fracture
- Conchoidal
- Lustre
- Adamantine to vitreous
Optical Properties
- Refractive Index
- 1.925
- Birefringence
- 0.059
- Optical Character
- Uniaxial +
- Dispersion
- 0.039
- Pleochroism
- weak: Body color / Lighter shade (Blue zircon shows colorless/blue dichroism; weak in most colors)
- Fluorescence
- Usually inert; some weak yellow-orange
Characteristics
Colours
Blue (heated)ColorlessGolden/yellowBrownGreen (metamict)RedOrange
Localities
Cambodia (Ratanakiri)MyanmarSri LankaTanzaniaVietnamAustralia
Common Inclusions
Parallel growth linesDoublet reflections (from birefringence)Apatite crystalsMonazite crystalsMetamict texture (treacle effect)
Known Treatments
Heat treatment (to blue, colorless, golden)
Crystal Forms
tetragonal_prismtetragonal_dipyramid
Diagnostic Features
Very high RI and dispersion; strong doubling (high type); metamict varieties exist
Related Minerals
Other minerals in the tetragonal system
