Lepidolite

The alkali metals of Group I are found chiefly as the chlorides (in the earth s crust and in sea water), and also as sulphates and carbonates. Lithium occurs as the aluminatesilicate minerals, spodimene and lepidolite. Of the Group II metals (beryllium to barium) beryllium, the rarest, occurs as the aluminatesilicate, beryl-magnesium is found as the carbonate and (with calcium) as the double carbonate dolomite-, calcium, strontium and barium all occur as carbonates, calcium carbonate being very plentiful as limestone. 

It does not occur free in nature combined it is found in small units in nearly all igneous rocks and in the waters of many mineral springs. Lepidolite, spodumeme, petalite, and amblygonite are the more important minerals containing it. 

Cesium, an alkali metal, occurs in lepidolite, pollucte (a hydrated silicate of aluminum and cesium), and in other sources. One of the world s richest sources of cesium is located at Bernic Lake, Manitoba. The deposits are estimated to contain 300,000 tons of pollucite, averaging 20% cesium. 

L. rubidus, deepest red) Discovered in 1861 by Bunsen and Kirchoff in the mineral lepidolite by use of the spectroscope. 

The element is much more abundant than was thought several years ago. It is now considered to be the 16th most abundant element in the earth s crust. Rubidium occurs in pollucite, leucite, and zinnwaldite, which contains traces up to 1%, in the form of the oxide. It is found in lepidolite to the extent of about 1.5%, and is recovered commercially from this source. Potassium minerals, such as those found at Searles Lake, California, and potassium chloride recovered from the brines in Michigan also contain the element and are commercial sources. It is also found along with cesium in the extensive deposits of pollucite at Bernic Lake, Manitoba. 

Rubidium was discovered as a minor constituent of lepidolite by R. W. Bunsen and G. R. Kirchhoff in 1861 only a few months after their discovery of caesium (1860) in mineral spa waters. These two elements were the first to be discovered by means of the spectroscope, which Bunsen and Kirchhoff had invented the previous year (1859) accordingly their names refer to the colour of the most prominent lines in their spectra (Latin rubidus, deepest red caesius, sky blue). 

Rubidium (78 ppm, similar to Ni, Cu, Zn) and caesium (2.6 ppm, similar to Br, Hf, U) are much less abundant than Na and K and have only recently become available in quantity. No purely Rb-containing mineral is known and much of the commercially available material is obtained as a byproduct of lepidolite processing for Li. Caesium occurs as the hydrated aluminosilicate pollucite, Cs4ALiSi9026.H20, but the world s only commercial source is at Bemic Lake,... 

Lithium is extracted from the ores lepidolite and spodumene, which contain up to 8% lithium oxide. The ore is converted first to lithium sulfate by acid roasting at 250°C and then to lithium chloride via the carbonate. Electrolysis of the fused... 

Complex Spodumene Beryl Tantalite Lepidolite Ambylgonite Topaz Li, Rb, Cs, Be, Ta, Sn, Ga Manono, Zaire Hugo, South Dakota Tanco, Manitoba Londonberry, Australia Marlagalla, India... 

Robert Wilhelm Bunsen (1811-1899) and Gustav Robert Kirchhoff (1824-1887) discovered it in the mineral lepidolite through spectral analysis. 

Lentinan, 20 578 Lenzing patent, 77 266-267, 268 Leonite, 5 785t Lepidolite, 75 123... 

Lepidolite, rubidium-bearing, 27 818 Lepirudin, 4 100, lOOt, 101 Leptin, 3 96-97 Lepton accelerator, 23 862 Leptons, 27 297, 298, 299 conservation of, 27 305 Leptophos, 4 358t Lercanidipine, 5 132-133... 

Occurrence. Its most important minerals correspond to alumino-silicates LiAlSi206 (spodumene), LiAlSi4O10 (petalite), lithium mica (lepidolite), LiAlSi04 (as the rare eukryptite). 

Occurrence. Unlike its homologues Li and Cs, Rb is not a major component of any mineral. It is found mainly in association with K (similarity of their ionic radii) and also with other alkali metals (with Li in lepidolite, with Cs in pollucite). 

Rubidium - the atomic number is 37 and the chemical symbol is Rb. The name derives from the Latin rubidus for deepest red because of the two deep red lines in its spectra. It was discovered in the mineral lepidolite by the German chemist Robert Wilhelm Bunsen and the German physicist Gustav-Robert Kirchoff in 1861. Bimsen isolated rubidium in 1863. 

Lithium is contained in minute amounts in the mineral ores of spodumene, lepidolite, and amblygonite, which are found in the United States and several countries in Europe, Africa, and South America. High temperatures are required to extract lithium from its compounds and by electrolysis of lithium chloride. It is also concentrated by solar evaporation of salt brine in lakes. 

Rubidium does not exist in its elemental metallic form in nature. However, in compound forms it is the 22nd most abundant element on Earth and, widespread over most land areas in mineral forms, is found in 310 ppm. Seawater contains only about 0.2 ppm of rubidium, which is a similar concentration to lithium. Rubidium is found in complex minerals and until recently was thought to be a rare metal. Rubidium is usually found combined with other Earth metals in several ores. The lepidolite (an ore of potassium-lithium-aluminum, with traces of rubidium) is treated with hydrochloric acid (HCl) at a high temperature, resulting in lithium chloride that is removed, leaving a residue containing about 25% rubidium. Another process uses thermochemical reductions of lithium and cesium ores that contain small amounts of rubidium chloride and then separate the metals by fractional distillation. 

Table 5.55 Chemical analyses of natural micas (from Deer et al., 1983). Note that ionic fractions are retrieved on a 24-anion basis—i.e. double the canonical formula. (1) Muscovite from a low-grade metamorphic prasinite schist (2) glauconite from a sandstone (3) phlogopite from a marble (4) biotite from a quartz-bearing latite (5) lepidolite from a pegmatite. ...

Sartori F. (1976). The crystal structure of IM lepidolite. Tsch. Min. Petr. Mitt., 23 65-75. 

Synonyms Mica is a nonfibrous silicate occurring in plate form and includes nine different species muscovite is a hydrated aluminum potassium silicate also called white mica phlo-gopite is an aluminum potassium magnesium silicate also called amber mica other forms are biotite, lepidolite, zinnwaldite, and roscoelite... 

Cesium was discovered by Bunsen and Kirchoff in 1860. It is found in the minerals pollucite, lepidolite, and the borate rhodizite. Pollucite, CsAlSi206, is a hydrated silicate of aluminum and cesium. The concentration of cesium in the earth s crust is estimated to be 3 mg/kg, and in sea water 0.3pg/L. 

Rubidium is recovered from its ore lepidolite or pollucite. Mineral lepidolite is a lithium mica having a composition KRbLi(OH,F)Al2Si30io. The ore is opened by fusion with gypsum (potassium sulfate) or with a mixture of barium sulfate and barium carbonate. The fused mass is extracted with hot water to leach out water-soluble alums of cesium, rubidium, and potassium. The solution is filtered to remove insoluble residues. Alums of alkali metals are separated from solution by fractional crystallization. Solubility of rubidium alum or rubidium aluminum sulfate dodecahydrate, RbAl(S04)2 I2H2O falls between potassium and cesium alum. 

On February 23, 1861, only a few months after the discovery of cesium, Bunsen and Kirchhoff announced to the Berlin Academy the existence of another new alkali metal in lepidolite. 

Klaproth said that lepidolite, the first source of rubidium, was discovered by the Abb6 Nicolaus Poda of Neuhaus (1723 -1798), a Jesuit... 

Klaproth s first analysis of lepidolite did not show the presence of any alkali. When he examined it a second time, however, he wrote Since the analysis of leucite, described in the earlier part of this work, has evidently proved that it contains the vegetable alkali as one of its essential constituent parts, it was to be expected that this alkaline substance might likewise be found in the mixture of various other species of stones and earths. The first confirmation of this conjecture has been afforded to me by the Lepidolite. His final analysis of "the amethystine red lepidolite yielded silica 54.50, alumina 38.25, potash 4, oxides of manganese and iron 0.75, and loss, partly consisting of water 2.50 per cent (71). Klaproth s analysis failed to show the presence of two essential constituents of lepidolite lithium (which had not yet been discovered) and fluorine. 

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