Minerals information from combined

Since then this method has been used to solve numerous other complex crystal structures [6-13]. Because solving a stmcture from a single projection requires a short (3 to 5 A) crystal axis, the method was later extended to combine the information from several orientations which allows also to uncover stmctures with pronounced overlap of the atom columns in projection. This technique was applied in 1990 to solve the 3D stmcture of the mineral staurolithe HFe2Al9Si404 [14, 15] and more recently to determine the stmcture of the huge quasicrystal approximant v-AlCrFe [16] which contains 129 atoms per as5mimetric unit. How CIP works to solve a crystal stmcture from projected data is shown in figure 10 (for further details see [17]). 

The isotope composition of biogenic and authigenic mineral precipitates from lake sediments can be used to infer changes in either temperature or the isotope composition of lake water. Knowledge of the factors that may have influenced the isotope composition of the lake water is essential for the interpretation of the precipitated phases (Leng and Marshall 2004). In many lakes the combined analysis of different types of authigenic components (precipitated calcite, ostracodes, bivalves, diatoms, etc.) may offer the possibility of obtaining seasonally specific information. 

There are approximately 130 different minerals that contain tantalum and niobium, from which about 80 are Ta/Nb only. The other minerals contain tantalum and niobium in the form of impurities. There is very little information available on beneficiation of Ta/Nb-containing ores. In actual practice, there are three basic methods for production of Ta/Nb concentrate (a) physical preconcentration, (b) combination of physical preconcentration and flotation and (c) direct flotation. In most cases, Ta/Nb ores contain significant quantities of zircon and rare earth ores (REO). 

An elaborate and novel system was devised by Richard and Coursin (168,169,170,171) whereby 19 constituents (minerals, sugars, acids, amino acids) were determined and evaluated by a heirarchial classification approach. By means of a series of inequalities, based on deviations from the mean, a region of authentic juice is defined in a multidimensional space. A series of regression equations between parameters (with R > 0.9) are considered next to verify that the relationships between constituents are normal. Finally, the above information may be combined in a matrix approach to give an estimate of juice content. 

A prototypical example of a molecular probe used extensively to study the mineral adsorbent-solution interface is the ESR spin-probe, Cu2+ (Sposito, 1993), whose spectroscopic properties are sensitive to changes in coordination environment. Since water does not interfere significantly with Cu11 ESR spectra, they may be recorded in situ for colloidal suspensions. Detailed, molecular-level information about coordination and orientation of both inner- and outer-sphere Cu2+ surface complexes has resulted from ESR studies of both phyllosilicates and metal oxyhydroxides. In addition, ESR techniques have been combined with closely related spectroscopic methods, like electron-spin-echo envelope modulation (ESEEM) and electron-nuclear double resonance (ENDOR), to provide complementary information about transition metal ion behaviour at mineral surfaces (Sposito, 1993). The level of sophistication and sensitivity of these kinds of surface speciation studies is increasing continually, such that the heterogeneous colloidal particles in soils can be investigated ever more accurately. 

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