Rob Lavinsky, iRocks.com – CC-BY-SA-3.0 [CC-BY-SA-3.0], via Wikimedia Commons
Rutile is often cut as a curiosity, but the finished gem is disappointing because it is so dark. The gems are usually deep red in color, but the color is so intense that it cannot be easily seen in stones larger than 1 carat. Cabochons of rutile might show reddish reflections in cracks and along imperfections. Swiss rutile seems a bit more transparent than material from other localities.
Rutile Value
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Rutile Information
| Data | Value |
| Name | Rutile |
| Crystallography | Tetragonal. Crystals prismatic, vertically striated, well developed, often twinned into a series of contact twins with up to eight individuals, sometimes looping to form a complete circle! Also, massive; granular. |
| Colors | Black, deep red, brownish red. Greenish (if Nb present), also bluish and violet. A variety rich in Cr is deep green. |
| Luster | Metallic to adamantine. |
| Hardness | 6-6.5. |
| Density | 4.23; ferroan variety = 4.2-4.4; with Nb and Ta = 4.2-5.6. |
| Birefringence | 0.287. |
| Cleavage | Distinct 1 direction. Fracture conchoidal to uneven. Brittle. |
| Dispersion | 0.280. |
| Stone Sizes | Large crystals often have transparent areas that can provide stones for faceting. However, a cut rutile above 2-3 carats is so dark it looks opaque, effectively limiting the size of cut gems. Devonian Group (Calgary, Alberta, Canada): 3.70. |
| Luminescence | None. |
| Spectral | Not diagnostic. |
| Formula | TiO2 + Nb, Ta, Fe. |
| Pleochroism | Distinct: shades of red, brown, yellow, green. |
Optics: o= 2.62; e = 2.90.
Uniaxial (+).
Sometimes anomalously biaxial.
Occurrence: Commonly seen as needles in quartz (rutillated quartz) and in agate (sagenite). Also present as fibers in corundum, creating stars in these gems. Present as needle inclusions in a wide variety of gem minerals. Also occurs as a high-temperature mineral, in gneiss and schist, also in Alpine—type veins; found in igneous rocks, pegmatites, regionally metamorphosed rocks, including crystalline limestones, and as detrital grains.
Virginia: North Carolina; South Dakota; California.
USSR; Switzerland; France.
Graves Mountain, Georgia: in quartz veins, fine crystals, up to several pounds in size.
Magnet Cove, Arkansas: in huge rough crystals.
Brazil: large, fine crystals.
Comments: Rutile is often cut as a curiosity, but the finished gem is disappointing because it is so dark. The gems are usually deep red in color, but the color is so intense that it cannot be easily seen in stones larger than 1 carat. Cabochons of rutile might show reddish reflections in cracks and along imperfections. Swiss rutile seems a bit more transparent than material from other localities.
Name: From the Latin rutilus (red), in allusion to the color.
