Rutile
Rutile is a very rare gem that is one of the three forms of Titanium Dioxide (TiO2) found in nature. The other two are Brookite and Anatase. Rutile is usually such a deep red, that large gems are too dark to be appreciated. Smaller gems show the intense red color better. Rutile is also commonly seen as needles in quartz (rutilated quartz) and other gem minerals. Rutile is common worldwide, but gem quality crystals are very rare and often kept as mineral specimens.
| Category: | Oxide minerals |
| Formula: | TiO2 |
| titanium dioxide | |
| Crystallography: | Tetragonal – Ditetragonal Dipyramidal |
| Crystal Habit: | Crystals are prismatic, elongated and striated, to 25 cm, many others; equant, rarely dipyramidal; massive. |
| Cleavage: | [110], good; [100], moderate; [111], in traces |
| Fracture: | Conchoidal, Subconchoidal, Uneven |
| Tenacity: | Brittle |
| Moh’s Hardness: | 6.0 – 6.5 |
| Density: | 4.23 – 4.25 (g/cm3) |
| Radioactivity: | Not Radioactive |
| Color: | Red, Reddish brown, pale yellow, pale blue, violet, black, rarely green |
| Transparency: | Transparent to Opaque |
| Luster: | Adamantine to Submetallic |
| Refractive Index: | 2.605 – 2.901 Uniaxial (+) |
| Birefringence: | 0.287 |
| Dispersion: | Strong |
| Pleochroism: | Distinct; shades of red, brown, yellow, green |
| Anisotropism: | Strong |
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