Rock forming minerals

Although there are more than 2,000 minerals identified, only a few are the most common rock-forming minerals. These are listed in Table 5.1. 

The structural classification of silicates is based on the polymerization of silicon tetrahedra (Si04) and on the proportion of silicon-to-oxygen atoms (Si 0) as follows  

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Aluminosilicates. These silicates consist of frameworks of silica and alumina tetrahedra linked at all corners to form three-dimensional networks familiar examples are the common rock-forming minerals quartz and feldspar. Framework silicates generally form blocky crystals, more isotropic... 

Stdffler, D. (1972), Deformation and Transformation of Rock-Forming Minerals by Natural and Experimental Shock Processes, I, Fortschr. Miner. 49, 50-113. 

Chao, E.C.T., Chock Effects in Certain Rock-Forming Minerals, Science 156, 192-202(1967). 

Magnesium. Mg, at wt 24.312, at no 12, valence 2. Isotopes 24 (77.4%), 25 (11.5%) 26 (11.1%). Physical properties of 99.9% pure Mg are (riven in the fnllnwino tsKle fRef 10 n 6791 Mg is very abundant in nature, occurring in substantial amounts in many rock-forming minerals such as dolomite, magnesite, olivine, and serpentine. In addition, it is also found in sea water, subterranean brines, and salt beds. 

The simplest proxy to identify is that of Ba for Ra. As noted above, both are heavy alkaline earths, which form large divalent cations. They exclusively enter large cation sites with at least Vlll-fold coordination. There are a large number of Ba partition coefficients for the major rock-forming minerals over a wide range of conditions, which make it an ideal proxy. 

Deer, L., B. L. Howie, and A. Zussman (1992), An Introduction to Rock Forming Minerals, Longmans, London. 

Langer, K. Frentrup, K.R. Automated-Microscope-Absorption-Spectrophotometry of Rock-Forming Minerals in the Range 250-2000 nm, J. Microscopy. 1979, 116, 311-320. 

Helgeson, H. C., J. M. Delany, H. W. Nesbitt and D. K. Bird, 1978, Summary and critique of the thermodynamic properties of rock-forming minerals. American Journal of Science 278-A, 1-229. 

Deer, W.A., Howie, R.A. and Zussman, J. (1962, 1963). Rock-Forming Minerals. Longmans, London (5 vols). 

Feldspars are the most abundant minerals of igneous and metamorphic rocks 0 2). Being the most abundant rock-forming minerals of the earth s crust, they have received a proportionately large share of attention from students of weathering, and most of the major analytical advances and conceptual models which have been applied to other mineral groups have also been applied to feldspars. 

Deer WA, Howie RA, Zussman J. 1992. An Introduction to the Rock-Forming Minerals. Harlow Longman Scientific and Technical. 

Figure 2.6 shows P-T stability diagrams for several components exhibiting polymorphism in geology (the Co2Si04 orthosilicate, which is not a major constituent of rock-forming minerals, is nevertheless emblematic of phase transitions observed in the earth s mantle cf section 5.2.3). 

The application of Landau theory to rock-forming minerals has been promoted by Ekhard Salje and his coworkers in an attempt to achieve better quantification of complex transition phenomena (mainly in feldspars, but also in pyroxenes and spinels Salje etal., 1985 Salje, 1985,1988 Carpenter and Salje, 1994a,b Carpenter, 1988). 

Table 3.2 Coefficients of Berman-Brown polynomials for the commonest oxide constitnents of rock-forming minerals. The resulting Cp is in J/(mole X K) (from Berman and Brown, 1985).

Table 3.2 lists the optimal values of the interpolation coefficients estimated by Berman and Brown (1987) for the most common oxide constituents of rock-forming minerals. These coefficients, through equations 3.78.1, 3.78.2, and 3.78.3, allow the formulation of polynomials of the same type as equation 3.54, whose precision is within 2% of experimental Cp values in the T range of applicability. However, the tabulated coefficients cannot be applied to phases with lambda transitions (see section 2.8). 

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