Samarskit

Cerium is the most abundant so-called rare-earths metal. It is found in a number of minerals including ahanite (also known as orthite), monazite, bastnasite, cerhe, and samarskite. Monazite and bastnasite are presently the two more important sources of cerium. 

Gr. prasios, green, and didymos, twin) In 1841 Mosander extracted the rare earth didymia from lanthana in 1879, Lecoq de Boisbaudran isolated a new earth, samaria, from didymia obtained from the mineral samarskite. Six years later, in 1885, von Welsbach separated didymia into two others, praseodymia and neodymia, which gave salts of different colors. As with other rare earths, compounds of these elements in solution have distinctive sharp spectral absorption bands or lines, some of which are only a few Angstroms wide. 

Samarskite, a mineral) Discovered spectroscopically by its sharp absorption lines in 1879 by Lecoq de Boisbaudran in the mineral samarskite, named in honor of a Russian mine official. Col Samarski. 

Name discovered in the mineral samarskite (Samarsky was a Russian geologist)... 

Samarium (Sm, [Xe]4/66.r). Name and symbol after the mineral samarskite. Discovered (1879) by Paul Emile Lecoq de Boisbaudran. 

It should be noted that the ytterbium listed above was a mixture discovered in the mineral erbia by de Marignac in 1878 and not the neoytterbium/aldebaranium element renamed ytterbium that was foimd in the mineral ytterbia. The columbium was a mixture found in the mineral samarskite and was not the present day columbium/niobium. The ionium listed above was a mixture of terbium and gadolinium that was found in the mineral yttria and does not refer to °Th. Finally, the neptunium refers to material fovmd in niobium/tantalum minerals and does not refer to the 1940 discovery of the trans-uranium element produced via a neutron capture reaction on a uranium sample. 

Dysprosium - the atomic number is 66 and the chemical symbol is Dy. The name derives from the Greek dysprositos for hard to get at , due to the difficulty in separating this rare earth element from a holmium mineral in which it was found. Discovery was first claimed by the Swiss chemist Marc Delafontaine in the mineral samarskite in 1878 and he called it philippia. Philippia was subsequently found to be a mixture of terbium and erbium. Dysprosium was later discovered in a holmium sample by the French chemist Paul-Emile Lecoq de Boisbaudron in 1886, who was then credited with the discovery. It was first isolated by the French chemist George Urbain in 1906. 

Gadolinium - the atomic number is 64 and the chemical symbol is Gd. The name derives from the mineral gadolinite, in which it was found, and which had been named for the Finnish rare earth chemist Johan Gadolin . It was discovered by the Swiss chemist Jean-Charles Galissard de Marignac in 1886, who produced a white oxide he called Y in a samarskite mineral. In 1886, the French chemist Paul-Emile Lecoq de Boisbaudran gave the name gadolinium to Y . 

ORIGIN OF NAME It is named after the mineral samarskite. 

Samarium is the 39th most abundant element in the Earths crust and the fifth in abundance (6.5 ppm) of all the rare-earths. In 1879 samarium was first identified in the mineral samarskite [(Y, Ce U, Fe) (Nb, Ta, Ti )Ojg]. Today, it is mostly produced by the ion-exchange process from monazite sand. Monazite sand contains almost all the rare-earths, 2.8% of which is samarium. It is also found in the minerals gadolmite, cerite, and samarskite in South Africa, South America, Australia, and the southeastern United States. It can be recovered as a byproduct of the fission process in nuclear reactors. 

Using a spectrometer in 1853, Jean Charles-GaUisard de Marignac (1817—1894) suspected that dydimia was a mixture of yet-to-be-discovered elements. However, it was not until 1879 that Paul-Emile Locoq de Boisbaudran (1838—1912), using a difficult chemical fractionation process, discovered samarium in a sample of samarskite, calling it samarium after the mineral, which was named for a Russian mine official. Colonel von Samarski. Samarskite ore is found where didymia is found. Didymia ( twins ) was the original name given to a combination of the two rare-earths (praseodymium and neodymium) before they were separated and identified. 

The element was discovered by Klaproth in 1803 and also in the same year by Berzelius and Hisinger. It is named after the asteroid Ceres. Cerium is found in several minerals often associated with thorium and lanthanum. Some important minerals are monazite, aUanite, cerite, bastnasite, and samarskite. It is the most abundant element among aU rare-earth metals. Its abundance in the earth s crust is estimated to be 66 mg/kg, while its concentration in sea water is approximately 0.0012 microgram/L. 

Minerals such as euxenite, fergusonite, samarskite, polycrase and loparite are highly refractory and complex in nature. These minerals may be opened up by treatment with hydrofluoric acid. While metals such as niobium, tantalum and titanium form soluble fluorides, rare earth elements form an insoluble residue of their fluorides. Such insoluble fluorides are filtered out of solution and digested with hot concentrated sulfuric acid. The rare earth sulfates formed are dissolved in cold water and thus separated from the insoluble mineral impurities. Rare earth elements in the aqueous solution are then separated by displacement ion exchange techniques outlined above. 

Mosander extracted from the mineral lanthana a rare earth fraction, named didymia in 1841. In 1879, Boisbaudran separated a rare earth oxide called samaria (samarium oxide) from the didymia fraction obtained from the mineral samarskite. Soon after that in 1885, Baron Auer von Welsbach isolated two other rare earths from didymia. He named them as praseodymia (green twin) and neodymia (new twin) after their source didymia (twin). The name praseodymium finally was assigned to this new element, derived from the two Greek words, prasios meaning green and didymos meaning twin. 

The discovery of samarium is credited to Boisbaudran, who in 1879 separated its oxide, samaria from Mosander s didymia, the mixture of rare earth oxides from which cerium and lanthanum were isolated earher. Demarcay in 1901 first identified samaria to be a mixture of samarium and europium oxides. The element got its name from its mineral, samarskite. The mineral, in turn, was named in honor of the Russian mine official Col. Samarki. 

Tantalum is never found in nature in free elemental form. The most important mineral is columbite-tantalite (Ee,Mn) (Nb,Ta)206. Tantalum also is found in minor quantities in minerals pyrochlore, samarskite, euexenite, and fergusonite. The abundance of tantalum in the earth s crust is estimated as 2 mg/kg. 

Thulium was discovered in 1879 by Cleve and named after Thule, the earliest name for Scandinavia. Its oxide thulia was isolated by James in 1911. Thulium is one of the least abundant lanthanide elements and is found in very small amounts with other rare earths. It occurs in the yttrium-rich minerals xenotime, euxenite, samarskite, gadolinite, loparite, fergusonite, and yttroparisite. Also, it occurs in trace quantities in minerals monazite and... 

F. Lawrence Smith, 1818-1883. American nuneralog ieal and analytical chemist Ills method of decomposing ores which are to be analyzed for sodium and potassium is still the standard procedure He investigated the rare earths m samarskite and verified Mosander s conclusions regarding the complex nature of yttna. 

Samarskite occurs in the Ural Mountains, Mitchell County (North Carolina, U.S.A.), Canada, and India. The tantalum content is often small, sometimes nil, and the rare earth oxides, chiefly yttria and ceria, are usually present in considerable number and proportions. The ore is radioactive and contains helium. It forms black, orthorhombic crystals. The density varies from 4-2 to G-2.5 It has been suggested that the niobium and tantalum are disintegration products of compounds of yttrium and cerium with the two higher homologues of manganese,4 masurium, and rhenium. 

Euxenite, ceschyniie,7 and polycrase are found in Norway, and differ in composition from samarskite in that they usually contain considerable quantities of titanium. Tantalum is not always present.8... 

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