Ilmenite known as manaccanite, is a titanium-iron oxide mineral with the idealized formula FeTiO3. It is a weakly magnetic black or steel-gray solid. From a commercial perspective, ilmenite is the most important ore of titanium. Ilmenite is the main source of titanium dioxide, used in paints, printing inks, plastics, sunscreen and cosmetics. Ilmenite crystallizes in the trigonal system; the ilmenite crystal structure consists of an ordered derivative of the corundum structure. Containing high spin ferrous centers, ilmenite is paramagnetic. Ilmenite is recognized in altered igneous rocks by the presence of a white alteration product, the pseudo-mineral leucoxene. Ilmenites are rimmed with leucoxene, which allows ilmenite to be distinguished from magnetite and other iron-titanium oxides; the example shown in the image at right is typical of leucoxene-rimmed ilmenite. In reflected light it may be distinguished from magnetite by more pronounced reflection pleochroism and a brown-pink tinge. Samples of ilmenite exhibit a weak response to a hand magnet.
In 1791 William Gregor discovered ilmenite, in a stream that runs through the valley just south of the village of Manaccan, identified for the first time Titanium as one of the constituents of ilmenite. Ilmenite most contains appreciable quantities of magnesium and manganese and the full chemical formula can be expressed as O3. Ilmenite forms a solid solution with geikielite and pyrophanite which are magnesian and manganiferous end-members of the solid solution series. Although there appears evidence of the complete range of mineral chemistries in the O3 system occurring on Earth, the vast bulk of ilmenites are restricted to close to the ideal FeTiO3 composition, with minor mole percentages of Mn and Mg. A key exception is in the ilmenites of kimberlites where the mineral contains major amounts of geikielite molecules, in some differentiated felsic rocks ilmenites may contain significant amounts of pyrophanite molecules. At higher temperatures it has been demonstrated there is a complete solid solution between ilmenite and hematite.
There is a miscibility gap at lower temperatures, resulting in a coexistence of these two minerals in rocks but no solid solution. This coexistence may result in exsolution lamellae in cooled ilmenites with more iron in the system than can be homogeneously accommodated in the crystal lattice. Altered ilmenite forms the mineral leucoxene, an important source of titanium in heavy mineral sands ore deposits. Leucoxene is a typical component of altered gabbro and diorite and is indicative of ilmenite in the unaltered rock. Ilmenite is a common accessory mineral found in igneous rocks, it is found in large concentrations in layered intrusions where it forms as part of a cumulate layer within the silicate stratigraphy of the intrusion. Ilmenite occurs within the pyroxenitic portion of such intrusions. Magnesian ilmenite is indicative of kimberlitic paragenesis and forms part of the MARID association of minerals assemblage of glimmerite xenoliths. Manganiferous ilmenite is found in granitic rocks and in carbonatite intrusions where it may contain anomalous niobium.
Many mafic igneous rocks contain grains of intergrown magnetite and ilmenite, formed by the oxidation of ulvospinel. Ilmenite occurs as discrete grains with some hematite in solid solution, complete solid solution exists between the two minerals at temperatures above about 950 °C. Titanium was identified for the first time by William Gregor in 1791 in ilmenite from the Manaccan valley in Cornwall, southwest England. Ilmenite is named after the locality of its discovery near Miass, Russia. Most ilmenite is mined for titanium dioxide production. In 2011, about 47% of the titanium dioxide produced worldwide were based on this material. Ilmenite and/or titanium dioxide are used in the production of Titanium metal. Titanium dioxide is most used as a white pigment and the major consuming industries for TiO2 pigments are paints and surface coatings and paper and paperboard. Per capita consumption of TiO2 in China is about 1.1 kilograms per year, compared with 2.7 kilograms for Western Europe and the United States.
Ilmenite can be converted into pigment grade titanium dioxide via either the sulfate process or the chloride process. Ilmenite can be improved and purified to Rutile using the Becher process. Ilmenite ores can be converted to liquid iron and a titanium rich slag using a smelting process. Ilmenite ore is used as a flux by steelmakers to line blast furnace hearth refractory. Ilmenite sand is used as a sandblasting agent in the cleaning of diecasting dies. Ilmenite can be used to produce ferrotitanium via an aluminothermic reduction. Australia was the world's largest ilmenite ore producer in 2011, with about 1.3 million tonnes of production, followed by South Africa, Mozambique, China, Ukraine, Norway and United States. Although most ilmenite is recovered from heavy mineral sands ore deposits, ilmenite can be recovered from layered intrusive sources or "hard rock" titanium ore sources; the top four ilmenite and rutile feedstock producers in 2010 were Rio Tinto Group, Iluka Resources and Kenmare Resources, which collectively accounted for more than 60% of world's supplies.
The world's two largest open cast ilmenite mines are: The Tellnes mine located in Sokndal and run by Titania AS with 0.55 Mtpa capacity and
Corundum is a crystalline form of aluminium oxide containing traces of iron, titanium and chromium. It is a rock-forming mineral, it is a transparent material, but can have different colors depending on the presence of transition metal impurities in its crystalline structure. Corundum has two primary gem varieties: sapphire. Rubies are red due to the presence of chromium, sapphires exhibit a range of colors depending on what transition metal is present. A rare type of sapphire, padparadscha sapphire, is pink-orange; the name "corundum" is derived from the Tamil word Kurundam, which in turn derives from the Sanskrit Kuruvinda. Because of corundum's hardness, it can scratch every other mineral, it is used as an abrasive on everything from sandpaper to large tools used in machining metals and wood. Some emery is a mix of corundum and other substances, the mix is less abrasive, with an average Mohs hardness of 8.0. In addition to its hardness, corundum has a density of 4.02 g/cm3, unusually high for a transparent mineral composed of the low-atomic mass elements aluminium and oxygen.
Corundum occurs as a mineral in mica schist and some marbles in metamorphic terranes. It occurs in low silica igneous syenite and nepheline syenite intrusives. Other occurrences are as masses adjacent to ultramafic intrusives, associated with lamprophyre dikes and as large crystals in pegmatites, it occurs as a detrital mineral in stream and beach sands because of its hardness and resistance to weathering. The largest documented single crystal of corundum measured about 65×40×40 cm, weighed 152 kg; the record has since been surpassed by certain synthetic boules. Corundum for abrasives is mined in Zimbabwe, Afghanistan, Sri Lanka, India, it was mined from deposits associated with dunites in North Carolina, US and from a nepheline syenite in Craigmont, Ontario. Emery-grade corundum is found on the Greek island of Naxos and near Peekskill, New York, US. Abrasive corundum is synthetically manufactured from bauxite. Four corundum axes dating back to 2500 BCE from the Liangzhou culture have been discovered in China.
In 1837, Marc Antoine Gaudin made the first synthetic rubies by reacting alumina at a high temperature with a small amount of chromium as a pigment. In 1847, Ebelmen made white synthetic sapphires by reacting alumina in boric acid. In 1877 Frenic and Freil made crystal corundum from. Frimy and Auguste Verneuil manufactured artificial ruby by fusing BaF2 and Al2O3 with a little chromium at temperatures above 2,000 °C. In 1903, Verneuil announced he could produce synthetic rubies on a commercial scale using this flame fusion process; the Verneuil process allows the production of flawless single-crystal sapphires and other corundum gems of much larger size than found in nature. It is possible to grow gem-quality synthetic corundum by flux-growth and hydrothermal synthesis; because of the simplicity of the methods involved in corundum synthesis, large quantities of these crystals have become available on the market causing a significant reduction of price in recent years. Apart from ornamental uses, synthetic corundum is used to produce mechanical parts, scratch-resistant optics, scratch-resistant watch crystals, instrument windows for satellites and spacecraft, laser components.
Corundum crystallizes with trigonal symmetry in the space group R3c and has the lattice parameters a = 4.75 Å and c = 12.982 Å at standard conditions. The unit cell contains six formula units; the toughness of corundum is sensitive to surface crystallographic orientation. It may be 6-7 MPa·m1/2 for synthetic crystals, ~4 for naturalIn the lattice of corundum, the oxygen atoms form a distorted hexagonal close packing, in which two-thirds of the gaps between the octahedra are occupied by aluminum ions
Abhurite is a mineral of tin, oxygen and chlorine with the formula Sn21O614Cl16 or Sn3O2Cl2. Its named after its type locality, a shipwreck with tin ingots at Sharm Abhur, a cove near Jeddah in the Red Sea. Abhurite forms alongside other tin minerals like cassiterite. Abhurite is attributed for forming on tin materials when in contact with sea water; the mineral was described in 1977 from a shipwreck near Hidra Island, where it occurred on pewter plates. However, that report was not recognized by International Mineralogical Association. Along with Sharm Abhur and the shipwreck near Hidra Island, abhurite was found on tin ingots in the Uluburun shipwreck. On the ingots, it was found with other tin minerals like cassiterite and romarchite, calcium carbonate minerals like calcite and aragonite. List of minerals
In geometry, a hexagon is a six-sided polygon or 6-gon. The total of the internal angles of any simple hexagon is 720°. A regular hexagon has Schläfli symbol and can be constructed as a truncated equilateral triangle, t, which alternates two types of edges. A regular hexagon is defined as a hexagon, both equilateral and equiangular, it is bicentric, meaning that it is both tangential. The common length of the sides equals the radius of the circumscribed circle, which equals 2 3 times the apothem. All internal angles are 120 degrees. A regular hexagon has 6 rotational symmetries and 6 reflection symmetries, making up the dihedral group D6; the longest diagonals of a regular hexagon, connecting diametrically opposite vertices, are twice the length of one side. From this it can be seen that a triangle with a vertex at the center of the regular hexagon and sharing one side with the hexagon is equilateral, that the regular hexagon can be partitioned into six equilateral triangles. Like squares and equilateral triangles, regular hexagons fit together without any gaps to tile the plane, so are useful for constructing tessellations.
The cells of a beehive honeycomb are hexagonal for this reason and because the shape makes efficient use of space and building materials. The Voronoi diagram of a regular triangular lattice is the honeycomb tessellation of hexagons, it is not considered a triambus, although it is equilateral. The maximal diameter, D, is twice the maximal radius or circumradius, R, which equals the side length, t; the minimal diameter or the diameter of the inscribed circle, d, is twice the minimal radius or inradius, r. The maxima and minima are related by the same factor: 1 2 d = r = cos R = 3 2 R = 3 2 t and d = 3 2 D; the area of a regular hexagon A = 3 3 2 R 2 = 3 R r = 2 3 r 2 = 3 3 8 D 2 = 3 4 D d = 3 2 d 2 ≈ 2.598 R 2 ≈ 3.464 r 2 ≈ 0.6495 D 2 ≈ 0.866 d 2. For any regular polygon, the area can be expressed in terms of the apothem a and the perimeter p. For the regular hexagon these are given by a = r, p = 6 R = 4 r 3, so A = a p 2 = r ⋅ 4 r 3 2 = 2 r 2 3 ≈ 3.464 r 2. The regular hexagon fills the fraction 3 3 2 π ≈ 0.8270 of its circumscribed circle.
If a regular hexagon has successive vertices A, B, C, D, E, F and if P is any point on the circumscribing circle between B and C PE + PF = PA + PB + PC + PD. The regular hexagon has Dih6 symmetry, order 12. There are 3 dihedral subgroups: Dih3, Dih2, Dih1, 4 cyclic subgroups: Z6, Z3, Z2, Z1; these symmetries express 9 distinct symmetries of a regular hexagon. John Conway labels these by a group order. R12 is full symmetry, a1 is no symmetry. P6, an isogonal hexagon constructed by three mirrors can alternate long and short edges, d6, an isotoxal hexagon constructed with equal edge lengths, but vertices alternating two different internal angles; these two forms have half the symmetry order of the regular hexagon. The
Cerite is a complex silicate mineral group containing cerium, formula 963. The cerium and lanthanum content varies with the La rich species. Analysis of a sample from the Mountain Pass carbonatite gave 35.05% Ce2O3 and 30.04% La2O3. Cerite was first described in 1803 for an occurrence in Bastnäs in Sweden; the lanthanum rich species, cerite- was first described for an occurrence in the Khibina massif, Kola Peninsula, Russia in 2002. Classification of minerals List of minerals Media related to Cerite- at Wikimedia Commons
A crystal or crystalline solid is a solid material whose constituents are arranged in a ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macroscopic single crystals are identifiable by their geometrical shape, consisting of flat faces with specific, characteristic orientations; the scientific study of crystals and crystal formation is known as crystallography. The process of crystal formation via mechanisms of crystal growth is called crystallization or solidification; the word crystal derives from the Ancient Greek word κρύσταλλος, meaning both "ice" and "rock crystal", from κρύος, "icy cold, frost". Examples of large crystals include snowflakes and table salt. Most inorganic solids are not crystals but polycrystals, i.e. many microscopic crystals fused together into a single solid. Examples of polycrystals include most metals, rocks and ice. A third category of solids is amorphous solids, where the atoms have no periodic structure whatsoever.
Examples of amorphous solids include glass and many plastics. Despite the name, lead crystal, crystal glass, related products are not crystals, but rather types of glass, i.e. amorphous solids. Crystals are used in pseudoscientific practices such as crystal therapy, along with gemstones, are sometimes associated with spellwork in Wiccan beliefs and related religious movements; the scientific definition of a "crystal" is based on the microscopic arrangement of atoms inside it, called the crystal structure. A crystal is a solid where the atoms form a periodic arrangement.. Not all solids are crystals. For example, when liquid water starts freezing, the phase change begins with small ice crystals that grow until they fuse, forming a polycrystalline structure. In the final block of ice, each of the small crystals is a true crystal with a periodic arrangement of atoms, but the whole polycrystal does not have a periodic arrangement of atoms, because the periodic pattern is broken at the grain boundaries.
Most macroscopic inorganic solids are polycrystalline, including all metals, ice, etc. Solids that are neither crystalline nor polycrystalline, such as glass, are called amorphous solids called glassy, vitreous, or noncrystalline; these have no periodic order microscopically. There are distinct differences between crystalline solids and amorphous solids: most notably, the process of forming a glass does not release the latent heat of fusion, but forming a crystal does. A crystal structure is characterized by its unit cell, a small imaginary box containing one or more atoms in a specific spatial arrangement; the unit cells are stacked in three-dimensional space to form the crystal. The symmetry of a crystal is constrained by the requirement that the unit cells stack with no gaps. There are 219 possible crystal symmetries, called crystallographic space groups; these are grouped into 7 crystal systems, such as hexagonal crystal system. Crystals are recognized by their shape, consisting of flat faces with sharp angles.
These shape characteristics are not necessary for a crystal—a crystal is scientifically defined by its microscopic atomic arrangement, not its macroscopic shape—but the characteristic macroscopic shape is present and easy to see. Euhedral crystals are those with well-formed flat faces. Anhedral crystals do not because the crystal is one grain in a polycrystalline solid; the flat faces of a euhedral crystal are oriented in a specific way relative to the underlying atomic arrangement of the crystal: they are planes of low Miller index. This occurs; as a crystal grows, new atoms attach to the rougher and less stable parts of the surface, but less to the flat, stable surfaces. Therefore, the flat surfaces tend to grow larger and smoother, until the whole crystal surface consists of these plane surfaces. One of the oldest techniques in the science of crystallography consists of measuring the three-dimensional orientations of the faces of a crystal, using them to infer the underlying crystal symmetry.
A crystal's habit is its visible external shape. This is determined by the crystal structure, the specific crystal chemistry and bonding, the conditions under which the crystal formed. By volume and weight, the largest concentrations of crystals in the Earth are part of its solid bedrock. Crystals found in rocks range in size from a fraction of a millimetre to several centimetres across, although exceptionally large crystals are found; as of 1999, the world's largest known occurring crystal is a crystal of beryl from Malakialina, Madagascar, 18 m long and 3.5 m in diameter, weighing 380,000 kg. Some crystals have formed by magmatic and metamorphic processes, giving origin to large masses of crystalline rock; the vast majority of igneous rocks are formed from molten magma and the degree of crystallization depends on the conditions under which they solidified. Such rocks as granite, which have cooled slowly and under great pressures, have crystallized.