Garnet olivine

Wood B. J., Hackler R. T. and Dobson D. P. (1994). Experimental determination of Mn-Mg mixing properties in garnet, olivine and oxide. Contrib. Mineral Petrol, 115 438-448. 

A) 2MgSiO + CaMgSi O + MgAl O Mg CaAl Si O g SiO orthopyrox. clinopyrox. spinel garnet olivine... 

Silicates having an O Si ratio larger than or equal to 4 are orthosilicates, i.e. the Si04 tetrahedra do not share atoms with each other, but with the polyhedra about the other cations. Examples olivines, M2Si04 (M = Mg2+, Fe2+) and garnets, M3M2[Si04]3 (M = Mg2+, Ca2+, Fe2+ M = Al3+, Y3+, Cr3+, Fe3+). 

Table 10.2 Upper concentration limits for Henry s law behavior in silicates and oxides. Abbreviations Ab = albite Sa = sanidine PI = plagioclase Pel = alkaline feldspar Rb-fel = Rb-feldspar Ne = nepheline Mu = muscovite 01 = olivine Di = diopside Cpx = clinopyroxene Oxp = orthyporoxene Amph = amphibole Par = pargasite Gr = garnet Ilm = ilmenite ...

Chatteijee N. (1987). Evaluation of thermochemical data on Fe-Mg olivine, orthopyroxene, spinel and Ca-Fe-Mg-Al garnet. Geochim. Cosmochim. Acta, 51 2515-2525. 

Finnerty T. A. (1977). Exchange of Mn, Ca, Mg and A1 between synthetic garnet, orthopyroxene, clinopyroxene and olivine. Carnegie Inst. Wash. Yb., 68 290-292. 

O Neill H.St. C. and Wood B. J. (1979). An experimental study of Fe-Mg partitioning between garnet and olivine and its calibration as a geothermometer. Contrib. Mineral Petrol, 70 59-70. 

The first and the simplest type is component exchange between phases without growth or dissolution of either phase. Examples include oxygen isotope exchange between two minerals, and Fe -Mg exchange between olivine and garnet or between olivine and melt. This is essentially a diffusion problem. 

Figure 3-5 MnO partition between and diffusion in two minerals, olivine and garnet. Diffusional anisotropy of olivine is ignored. Initially, MnO in both phases were 0.2 wt%. As the two minerals come into contact, there will be diffusion to try to reach the equilibrium state. The partition coefficient (Mn)oiiv/(Mn)gt is assumed to be 0.59. The diffusivity in olivine is assumed to be 10 times that in garnet, resulting in a wider diffusion profile with a smaller slope in olivine.

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