About Rutile
From Latin rutilus (= red), in allusion to the color.
Rutile hand-specimen
Formula: TiO2
System: Tetragonal
Color: Blood red, brownish
Lustre: Adamantine, Metallic
Hardness: 6–6½
Density: 4.23
System: Tetragonal
Color: Blood red, brownish
Lustre: Adamantine, Metallic
Hardness: 6–6½
Density: 4.23
XPL
PPL
Rutile #1 thin section (hFOV 2mm)
XPL
PPL
Sagenite #1 thin section (hFOV 2mm)
![[thumb]](http://microckscopic.ro/wp-content/uploads/rutile_parallel_06-1-150x150.jpg)
![[thumb]](http://microckscopic.ro/wp-content/uploads/sagenite_1_05-1-150x150.jpg)
Rutile PPL properties
Relief: High – Very High positive
Habit/Form: Crystals are elongate tetragonal prism with square or octogonal cross-sections. Also as slender, acicular, or hair like crystals, and anhedral grains. Rounded and abraided grains are common in some clastic sediments.
Color: Red, brownish red, yellowish, deep brown (Nb, Ta), green (Nb, Ta); may be opaque
Pleochroism: Absent – weak
Cleavage: Barely visible in thin sections; after {110} and {100}. Cleavage may control the orientation of fragments.
Habit/Form: Crystals are elongate tetragonal prism with square or octogonal cross-sections. Also as slender, acicular, or hair like crystals, and anhedral grains. Rounded and abraided grains are common in some clastic sediments.
Color: Red, brownish red, yellowish, deep brown (Nb, Ta), green (Nb, Ta); may be opaque
Pleochroism: Absent – weak
Cleavage: Barely visible in thin sections; after {110} and {100}. Cleavage may control the orientation of fragments.
Rutile XPL properties
Isotropy/Anisotropy: Anisotropic
Interference color: High-order cream (often is masked by colour); interference colors are very high but do not show well on account of total reflection.
Extinction angle: Parallel / 0° / straight; difficult to detect due to extreme birefringence
Twins: Rare; in large crystals.
Uniaxial/Biaxial: Uniaxial (+)
Optic axial angle (2V): –
Interference color: High-order cream (often is masked by colour); interference colors are very high but do not show well on account of total reflection.
Extinction angle: Parallel / 0° / straight; difficult to detect due to extreme birefringence
Twins: Rare; in large crystals.
Uniaxial/Biaxial: Uniaxial (+)
Optic axial angle (2V): –
Rutile distinguishing features under the microscope
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References
- Deer, W. A., Howie, R. A., & Zussman, J. (2013). An introduction to the rock-forming minerals (pp. 498). Mineralogical Society of Great Britain and Ireland, London.
- mindat.org – The Mineral Database
