Chapter 2. Crystal Chemistry of Silicate Pyroxenes

The geochemistry of the volatile trace elements As, Cd, Ga, In and Sn in the Earth’s mantle: New evidence from in situ analyses of mantle xenoliths

“…The even smaller Mn 2+ cation can enter into both the sixfold coordinated M1 and six-to eightfold coordinated M2 positions by substituting for the major elements Mg and Fe 2+ , although it is heavily ordered into the M2 site (Cameron and Papike, 1980;Pertermann and Hirschmann, 2002). Our results show that D cpx/opx for Mn behaves similarly to the partitioning of Fe 2+ , Ni and Co (Table 5 and Fig.…”

The (Na,Li)FeGe2O6 clinopyroxene-type series: a temperature-dependent single-crystal X-ray diffraction and 57Fe Mössbauer spectroscopic study

“…It seems that for the P2 1 /c phase of the (Li,Na)FeGe 2 O 6 series, both mechanisms are active while for the C2/c phase, the reduction in the O3-O3 edge is more dominant. Generally, the c-lattice parameter is related to the tetrahedral size, and it may change by altering the tetrahedral kinking angle or by changing O3-O3 edge (Cameron and Papike 1980;Mantovani et al 2014). In the (Li,Na) FeGe 2 O 6 series, the c-axis increases in the P2 1 /c phase, which can be related to the increase in the kinking angle of the chain of tetrahedra, stretching the chain along [0 0 1], thus increasing the axis.…”

“…It is now well established that clinopyroxenes low in Ca and Na such as kanoite MnMgSi 2 O 6 or pigeonite (Ca, Mg,Fe 2+ )(Mg,Fe 2+ )Si 2 O 6 show structural phase transitions as a function of temperature and pressure (Cameron and Papike 1980;Arlt and Armbruster 1997;Cámara et al 2002Cámara et al , 2003a. This especially holds true for the Li clinopyroxenes, which thus qualifies them as a favorite object for crystal-chemical investigations in the P-T-X space.…”

Pressure‐induced phase transitions in CuGeO3 from Raman spectroscopic studies†

“…25 However, on release of pressure the latter phase transforms to the LiNbO 3 -type phase. The unit cell volumes and V associated with the above-mentioned transitions in MgGeO 3 and FeGeO 3 are given in Table 2. Quenchable garnet and perovskite phases of CaGeO 3 crystal 26 have been obtained from high-pressure and high-temperature treatment of the wollastonite phase of CaGeO 3 .…”