Geochemistry lanthanides

Carbamoyl methyl Phosphine Oxide Derivatives The physicochemical properties of various aryl derivatives of CMPO have been investigated at the Vernadsky Institute of Geochemistry and Analytical Chemistry. Extraction of americium and lanthanides from nitric acid with solutions of diphenyl- and dibutyl-(diethylcarbamoylmethyl) phosphine oxides (Ph2Et2-CMPO and Bu2Et2-CMPO) in dichloroethane have been investigated as a function of the concentrations of the extractants and nitric acid (110, 111). The observed dependences are characterized... 

R.H. Byrne and E.R. Sholkovitz, Marine chemistry and geochemistry of the lanthanides 497 Author index 595... 

Crystal field theory is one of several chemical bonding models and one that is applicable solely to the transition metal and lanthanide elements. The theory, which utilizes thermodynamic data obtained from absorption bands in the visible and near-infrared regions of the electromagnetic spectrum, has met with widespread applications and successful interpretations of diverse physical and chemical properties of elements of the first transition series. These elements comprise scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel and copper. The position of the first transition series in the periodic table is shown in fig. 1.1. Transition elements constitute almost forty weight per cent, or eighteen atom per cent, of the Earth (Appendix 1) and occur in most minerals in the Crust, Mantle and Core. As a result, there are many aspects of transition metal geochemistry that are amenable to interpretation by crystal field theory. 

Byrne RH and Sholkovitz ER (1996) Marine chemistry and geochemistry of the lanthanides. In Gschneider KA Jr and Eyring L (eds.) Handbook on the Physics and Chemistry of Rare Earths, vol. 23, pp. 497-593. Amsterdam Elsevier Science. 

In the past few years, a number of review articles and books dealing with lanthanide geochemistry have appeared (e.g. Haskin and Paster 1979, Hanson 1980 and Henderson 1984). It is not our intention merely to duplicate this material, and the reader is referred to these publications, in particular the text book edited by Henderson (1984) which contains 13 chapters on various aspects of rare earth element geochemistry, to complement this review. 

Our major purpose is to demonstrate how the rare earths, and the lanthanides in particular, have provided unique insights into geochemistry and cosmochemistry. Many of the examples which we will use will be drawn from those aspects which have received rather less attention in previous reviews. These include the use of the rare earths to elucidate both the evolution of the moon and the composition and evolution of the continental crust of the earth. We will, however, attempt to provide some comment on all areas of geochemistry and cosmochemistry where lanthanides have added significantly to our understanding. 

A vast body of literature now exists on the use of the rare earth elements (principally the lanthanides) in terrestrial ingenous geochemistry. Much of this is summarised in work by Haskin (1979), Haskin and Paster (1979), Hanson (1980), Moller and Muecke (1984) and by Henderson (1984). Frey (1979) has reviewed all of... 

In many respects, the distribution of europium serves as an epitome of the usefulness of the lanthanides in geochemistry and cosmochemistry. By its en-... 

The rare earth minerals always contain a variety of rare earth elements. The study of the elemental distribution of rare earths in minerals and roeks has been a subject of geochemistry and mineral chemistry for many years. Their distribution basically follows the Oddo-Harkins rule (Oddo 1914, Harkins 1917) i.e., a lanthanide with even atomic number is more abundant than the neighboring lanthanides with odd atomic number in natural minerals. From the view point of the distribution of rare... 

P. MoUer, P. Cemy, and F. Saupe, Lanthanides, Tantalum and Niobium Mineralogy, Geochemistry, Characteristics of Primary Ore Deposits, Prospecting, Processing and Applications , Springer-Verlag, Berlin, 1989, p. 380. 

They have very close chemical properties with scandium and yttrium and the whole series is often referred as rare earth elements, since lanthanides were historically isolated from uncommon oxide-type minerals. However this term is not totally adequate, the lanthanides are not to be considered as rare, because even a scarce 4f-element such as lutetium is more abundant than silver (see Geology, Geochemistry, and Natural Abundances of the Rare Earth Elements). 

Geology, Geochemistry, and Natural Abundances of the Rare Earth Elements Lanthanides Coordination Chemistry Lanthanide Alkoxides. 

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