Rutile price, occurrence, extraction and uses
Rutile is a frequently occurring mineral from the mineral class of "oxides and hydroxides" with the chemical composition TiO2 and thus, chemically speaking, titanium dioxide.
Rutile crystallizes in the tetragonal crystal system and develops mostly short to long prismatic, vertically striped crystals and very often crystal twins in the form of polysynthetic, lamellar and cyclic triplets, quadruplets and sextuplets, but also granular to massive mineral aggregates. Most rutile crystals are between a few millimeters and a few centimeters in size. Crystals up to 25 cm in length could also be found. [3]
The color of the mostly transparent to translucent crystals varies between reddish brown and strong red, but can also be golden yellow, bluish or purple. Colorful tarnishing colors are also possible. The surfaces of the crystals have a diamond-like sheen.
Etymology and history
Rutile was described in 1803 by Abraham Gottlob Werner, who named the mineral based on its frequently occurring reddish color after the Latin word rutilus for red or reddish.
Until 1795, when its chemical composition became known, rutile was mistaken for a tourmaline group mineral.
classification
Already in the 1982th edition of the mineral classification according to Strunz, which has been out of date since 8, rutile belonged to the mineral class of "oxides and hydroxides" and there to the department of oxides with the general formula "MO2 and related compounds", where it was named after the "rutile" Row "with the system no. IV / D.02 and the other members cassiterite, plattnerite and varlamoffite.
In the last revised and updated Lapis mineral directory by Stefan Weiß in 2018, which, out of consideration for private collectors and institutional collections, is still based on this classic systematics by Karl Hugo Strunz, the mineral was given the system and mineral number. IV / D.02-10, which in the "Lapis system" corresponds to the department "Oxides with the molar ratio of metal: oxygen = 1: 2 (MO2 and relatives)".
The 2001th edition of Strunz's mineral systematics, valid since 2009 and updated by the International Mineralogical Association (IMA) until 9, also classifies rutile in the department of "Oxides with the molar ratio of metal: oxygen = 1: 2 and comparable". However, this is further subdivided according to the size of the cations involved and the crystal structure, so that the mineral is classified in the sub-section “With medium-sized cations; Chains of edge-linked octahedra "can be found, where it is also named after the" rutile group "with the system no. 4.DB.05 and the other members argutite, cassiterite, plattnerite, pyrolusite, tripuhyite, tugarinovite and varlamoffite.
The systematics of minerals according to Dana also assigns rutile to the class of "oxides and hydroxides", but initially to the "oxides" category. Here it is together with ilmenorutil, struverite, pyrolusite, cassiterite, plattnerite, argutite, squawcreekite and stishovite in the "rutile group (tetragonal: P42 / mnm)" with the system no. 04.04.01 to be found in the subsection "Simple oxides with a cation charge of 4+ (AO2)".
crystal structure
The rutile structure is a frequently occurring type of structure for AB2 compounds and, in contrast to the fluorite structure, is not based on the closest packing of spheres. The oxide anions are arranged in the manner of distorted and corrugated “hexagonal” layers, with half of the octahedral gaps between them being occupied by the titanium cations, but due to the tetragonal symmetry these corrugated layers do not form the closest packing of spheres. The crystal structure can therefore be better described as a tetragonal rod packing made of strands of edge-sharing [TiO6] octahedra (according to the Niggli notation: [TiO4 / 2O2 / 1]), which run parallel to the crystallographic c-axis. The strands are still linked via common corners to form a three-dimensional [TiO6 / 3] network, which in abbreviated form results in the sum formula TiO2. The titanium cations surrounded octahedrally by oxygen atoms thus have the coordination number 6, while the oxide anions are surrounded by three titanium atoms in a slightly distorted trigonal planar arrangement (coordination number 3).
A number of other inorganic compounds also crystallize in the rutile structure, including the oxides NbO2, TaO2, MnO2 and SnO2 as well as the fluorides CrF2, MnF2, FeF2, CoF2, NiF2, CuF2 and ZnF2.
Features
Morphologie
Rutile often forms prismatic crystals with a thick columnar to fine needle habit, on which the flat shapes {110} and {010} predominate and whose crystal faces are parallel stretched and striped. In addition to many other shapes, there are also ditetragonal prisms.
Enclosed in fine-needle to fibrous form, rutile is responsible for the asterism (star of light) that occurs in sapphires and rubies, among other things. In microscopic inclusions, in addition to hematite and other mineral inclusions, it can emphasize the “phantom crystals” observed especially in quartz.
Twins are generally found in rutile, which can be formed according to two laws: Twins, triplets and polysynthetic multifilaments are particularly common in lamellar or cyclic form according to (101), whereby the individuals meet at an angle of 65 ° 35 ′. Characteristic are knee-shaped, visor-shaped and V-shaped twins and even sextuplets that form closed rings. Twins according to (301) in the shape of a heart, whose vertical axes meet at 54 ° 44 ′, are less common. Both laws can also occur at the same time and thereby form a grid-like or reticulated aggregate, which is called sagenite.
Color
Rutile can occur in different colors, but most often it is found in reddish-brown to strong red and black colors. As inclusions (inclusions) in other minerals - such as quartz - rutile also shines in a strong golden yellow color and in this form is referred to as venus hair and is often processed into gemstones. On the other hand, bluish or purple tones appear rarely.
Chemical and physical properties
Rutile is insoluble in acids and infusible before the soldering tube. In its pure form it is weakly paramagnetic with a specific magnetic susceptibility (mass susceptibility) of 7,7 · 10−7 emu / Oe · mg, but if it also contains iron, it becomes antiferromagnetic [4].
Modifications and varieties.
Rutile is the most important and only modification of titanium dioxide that is stable at high temperatures. The other two are anatase and brookite.
Sagenite is called a variety of rutile, which has flat, reticulated to lattice-like intergrowths of needle-like fine rutile twins. It is also known as epitaxial (oriented) intergrowth.
Nigrin is the name of a ferrous, black rutile.
Education and Locations
Educational conditions
As a high-temperature and high-pressure mineral, rutile forms both magmatic and metamorphic and can be found as an accessory component in many rocks, including as a soap mineral in river sediments. Correspondingly, rutile can be found in association with many other minerals, such as adulara, albite, apatite, calcite, chlorite, ilmenite, pyrophyllite, titanite and quartz in addition to the other TiO2 modifications anatase and brookite already mentioned. With hematite, rutile also forms epitaxial adhesions.
Rutile occurs in eclogites and is the dominant Ti phase in garnet amphibolites.
Locations
As a frequent mineral formation, rutile can be found in many places around the world, with around 5900 locations being documented so far (as of 2019).
The “Graves Mountain Mine” in Lincoln County (Georgia), USA, where crystals up to 15 cm in size came to light, are worth mentioning due to its extraordinary mineral finds. Particularly beautiful rutile hematite epitaxies are known from the “Cavradi Gorge” near Sedrun in the Swiss canton of Graubünden and the municipality of Ibitiara in the Brazilian state of Bahia. In addition, rutile inclusions are often discovered in smoky quartz in Ibitiara and in the municipality of Itabira, which belongs to the state of Minas Gerais. Large knee or visor-shaped crystal twins up to about 7 cm in size were found at Golčův Jeníkov and Soběslav in the Czech Republic. [9] Crystals up to 3 cm in diameter and 5 cm in length were found in the Paragachay deposit on Mount Kapujuk, Autonomous Republic of Nakhichevan in Azerbaijan.
In Germany, rutile was found mainly in some regions of the Black Forest (Baden-Württemberg), in the Fichtelgebirge, Spessart, Bavarian Forest and Upper Palatinate Forest (Bavaria), Hesse, Lower Saxony, in the North Rhine-Westphalian Siebengebirge, the Eifel (Rhineland-Palatinate), in the Saarland, in the Saxon Ore Mountains, Schleswig-Holstein and Thuringia.
In Austria the mineral was found in Burgenland, on alpine fissures in many regions of Carinthia, Salzburg and Styria, in some regions of Lower Austria and Tyrol as well as in Upper Austria and Vorarlberg.
In Switzerland, rutile occurred mainly on alpine fissures in the cantons of Graubünden, Ticino and Valais.
Rutile could also be found in rock samples from the Mid-Atlantic Ridge and the Southwest Indian Ridge and outside the Earth on the moon, more precisely in the Fra Mauro highlands.
Largest producing countries
Worldwide, the mining reserves for the most important titanium minerals lmenite and rutile are estimated at 692,58 million tons, with the largest regional concentrations in China with 28,9%, Australia with 17,0% and India with 13,3% ( As of November 2014).
Usage
With a metal content of around 60%, rutile is the most important titanium mineral after ilmenite.
Titanium dioxide in the rutile modification is used as a white pigment due to its high refraction. In addition, it serves alone or in conjunction with cellulose as a covering for electrodes for arc welding, which improves welding or makes it possible in the first place.
Due to its semiconductor properties, rutile is used in dye solar cells, the so-called Grätzel cells. Its band gap is around 3,0 eV, so it can absorb light with a wavelength smaller than around 400 nm.
As a gem
Natural rutile is only occasionally processed into gemstones by collectors, as it usually forms crystals that are too small. Synthetic rutile, on the other hand, has been sold as an imitation diamond since 1948 under the trade name "Titania" or "Diamonite" (not to be confused with diamondite!), Whereby it even exceeds its gloss by six times as high dispersion (fire).
Rutile needles enclosed in other minerals are also popular, which in addition to the golden sheen also provide various optical effects such as asterism (star-shaped light reflections) and chatoyance (cat's eye effect).
Rutile price
