Pyrope garnet

Sato Y, Akaogi M., and Akimoto S. (1978). Hydrostatic compression of the synthetic garnets pyrope and almandine. J. Geophys. Res., 83 335-338. 

Garnet Pyrope Mg3Al2(Si04)3 and Grossular Ca3Al2(Si04)3... 

Figure 5.5 The crystal structure of garnet (pyrope) projected into a dodecahedron. Note the configuration of the eight-fold coordinated Mg sites (distorted cube) which share edges with [A106] octahedra and [Si04] tetrahedra.

Garnets (pyrope, almandine, spessartine, uvarovite, grossular, spessartine) Abrasives, blasting media, water jet cuttings, and water filtration. 

Garnet (pyrope, almamdine, spessartine, uvarovite, grossular, andradite) USA (101), India (100), Australia (100), and China 335,000 Almandine (8-250 mesh) 170-240... 

Broadband LIBS spectra for three garnet types - the Mg-AI pyrope type, the Ca-AI grossular type, and the Mn-AI spessartine type are shown in Figure 1. 

Fig.1. Example broadband LIBS spectra for a pyrope, grossular, and spessartine garnet. The clear differences observed in the broadband spectra reflect the chemical differences in the composition of the three garnets.

Classification Assignment Fig. 4. Confusion matrix for the HDPCA analysis of the four pyrope garnets. The nth row and column correspond to the nth pyrope type truth and HDPCS statistical assignment, respectively. 

Because of the importance of garnet in upper-mantle parageneses, the compressibility of this phase has been the subject of many experimental studies. Ha-zen and Finger (1978), studying the compressibility of pyrope, observed that the... 

Table 10.3 Defect equilibria affecting REE solubility in pyrope and their effects in bulk garnet/melt REE distribution (Morlotti and Ottonello, 1982)...

Armbruster T., Geiger C. A., and Lager G. A. (1992). Single-crystal X-ray structure study of synthetic pyrope ahnandine garnets at 100 and 293 K. Amer. Mineral, 77 512-521. Atkins P. W. (1978). Physical Chemistry. Oxford Oxford University Press. 

Cressey G. (1978). Exsolution in almandine-pyrope-grossular garnet. Nature, 271 533-534. 

Ganguly J., Cheng W., and O Neill H. St. C. (1993). Syntheses, volume, and structural changes of garnets in the pyrope-grossular join Implications for stability and mixing properties. Amer Mineral, 78 583-593. 

Geiger C. A., Newton R. C. and Kleppa O. I (1987). Enthalpy of mixing of synthetic almandine-grossular and almandine-pyrope garnets from high-temperature solution calorimetry. Geochim. Cosmochim. Acta, 51 1755-1763. 

Haselton H. T. and Newton R. C. (1980). Thermodynamics of pyrope-grossular garnets and their stabilities at high temperatures and pressures. J. Geophys. Res., 85 6973-6982. 

Hensen B. I, Schmid R., and Wood B. J. (1975). Activity-composition relationship for pyrope-grossular garnet. Contrib. Mineral Petrol, 54 161-166. 

Leitner B. I, Weidner D. J., and Liebermann R. C. (1980). Elasticity of single crystal pyrope and implications for garnet solid solution series. Phys. Earth Planet. Interiors., 22 111. 

Wood B. I (1988). Activity measurements and excess entropy-volume relationships for pyrope-grossular garnets. J. Geol, 96 721-729. 

Example 4.1. Suppose olivine and garnet are in contact and olivine is on the left-hand side (x<0). Ignore the anisotropic diffusion effect in olivine. Suppose Fe-Mg interdiffusion between the two minerals may be treated as one dimensional. Assume olivine is a binary solid solution between fayalite and forsterite, and garnet is a binary solid solution between almandine and pyrope. Hence, Cpe + CMg= 1 for both phases, where C is mole fraction. Let initial Fe/(Fe- -Mg) = 0.12 in olivine and 0.2 in garnet. Let Xq = (Fe/Mg)gt/ (Fe/Mg)oi = 3, >Fe-Mg,oi = 10 ° mm+s, and Dpe-Mg,gt =... 

Ganguly J., Cheng W., and Chakraborty S. (1998a) Cation diffusion in aluminosilicate garnets experimental determination in pyrope-almandine diffusion couples. Contrib. Mineral. Petrol. 131, 171-180. 

Wang L., Essene E.J., and Zhang Y. (1999) Mineral inclusions in pyrope crystals from Garnet Ridge, Arizona, USA implications for processes in the upper mantle. Contrib. Mineral. Petrol. 135, 164-178. 

Direct observation of immiscibility in pyrope-almandine-grossular garnet. 

Garnet activated by trivalent Cr is a promising system for tunable laser appUcations and those systems have been well studied. Cr + replaces Ap" in octahedral sites with a weak crystal field. The transition involved in laser action is T2- A2, a vibrationally broadened band. At room temperature it has a maximum in the 715-825 nm range with a decay time in the 100-250 ps range depending on AE between the E and T2 levels. When the AE is maximal, narrow fines also appear from the E level. At low temperatures, when thermal activation of the T2 level is difficult, J -lines luminescence becomes dominant with the main fine at 687 nm (Monteil at al. 1988). We studied pyrope artificially activated by Cr and also found the two emission types described above (Fig. 5.26). 

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