Photo of Rutile in Processed & Rough Form
Rutile is a mineral with a hardness of 6 out of 10 on the Mohs scale of mineral hardness [?]. These Tetragonally structured gems are made of titanium oxide, their full chemical compound being TiO2.
Rutile with anatase and brookite is a trimorph of titanium oxide in the Rutile group.
It forms characteristic slender prismatic striated lengthways, variably terminated and often geniculate twinned crystals of the tetragonal system. Elbow- and heart-shaped (geniculated) twin crystals are common.
It is hard, heavy, fragile, with perfect cleavage. It has a metallic to adamantine lustre and is most frequently pale brown to yellow. It is infusible, and insoluble in acid.
Rutile occurs as a common high-temperature, high pressure accessory mineral in igneous rocks and granite pegmatites and in regionally metamorphosed rocks including crystalline limestones, ir in quartz veins running through them. It occurs in concentration with other heavy minerals in sands derived from these rocks.
Aside from occurring as individual prismatic or acicular crystals, rutile as inclusions can be seen in many gemstones, for example, in quartz (called "maiden hair") or topaz, which is called rutilated quartz, rutilated topaz and in quartz or agate as sagenitic. Also can be seen in corundum. Rutile inclusions can also be seen in garnets, quartz, agate, sapphire, ruby, chrysoberyl, synthetic ruby, and sapphire.
Rutile needles are common inclusions in a number of gem minerals but fine unenclosed crystals are found at a number of Swiss locations. Splendid crystals are found in Alpine fissures (St. Gotthard, Tavetschtal, Cavradi, Castione) in Switzerland, and in pyrophyllite in Graves Mountain, Georgia (USA). It is common in apatite veins in Norway and in hornblende-bearing rocks in Nelson county, Virginia (USA). It is also found in Romania, Australia, Italy, Mexico, USA (Arkansas, Georgia, California, South Dakota). Large crystals are found at Conquista and Ibitiara, Bahia, Brazil.
The specific gravity [?] for Rutile is 4.25, its refractive index [?] is 2.62-2.90, and its double refraction [?] is 0.287.
History
Rutile derives its name from the Latin "rutilus," meaning "red", describing the deep red color observed in some rutile crystals when viewed by transmitted light.
Varieties of rutile are Venus's-hair stone, fleches d'amour, and sagenitic. It has an obsolete name "edisonite."
Rutile is also called red schorl, money stone.
Industrial Usages
Some transparent crystals are cut and faceted for gems and jewelry objects but they are so dark that they look opaque and are cut cabochon and for jewelry objects. Black stones are cut as mourning jewelry. Cut stones exhibit doubling of bottom facets with great birefringence and has six times more fire than diamond.
A synthetic rutile is made by the Verneuil flame-fusion method that is commercially known as titania, etc.
Rutile is an important commercial ore of titanium.
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