Diopside

Li Si O enstatite [14681-78-8] MgSiO diopside [14483-19-3], CaMgSi O and woUastonite [14567-57-2], CaSiO. A number of sihcate glass-ceramic compositions are given in Table 1. 

NaAs03 has an infinite polymeric chain anion similar to that in diopside (pp. 349, 529) but with a trimeric repeat unit LiAs03 is similar but with a dimeric repeat unit whereas /6-KASO3 appears to have a cyclic trimeric anion As309 which resembles the cyc/o-trimetaphosphates (p. 530). There is thus a certain structural similarity between arsenates and phosphates, though arsenic acid and the arsenates show less tendency to catenation (p. 526). The tetrahedral As 04) group also resembles PO4) in forming the central unit in several heteropoly acid anions (p. 1014). 

Grtin-spat, m. a variety of diopside. -star, m. glaucoma, -stein, m. (Geol.) greenstone, -stich, m. greemsh tinge or cast, -stift, m. green pencil, -sucht, /, chlorosis. 

More than 90% of the rocks and minerals found in the earth s crust are silicates, which are essentially ionic Typically the anion has a network covalent structure in which Si044-tetrahedra are bonded to one another in one, two, or three dimensions. The structure shown at the left of Figure 9.15 (p. 243), where the anion is a one-dimensional infinite chain, is typical of fibrous minerals such as diopside, CaSi03 - MgSi03. Asbestos has a related structure in which two chains are linked together to form a double strand. 

Silicate lattices. The red circles represent oxygen atoms. The black dot in die center of die red circle represents the Si atom, which is at the center of a tetrahedron. (Left) Diopside has a one-dimensional infinite chain. (Right) A portion of the talc structure, which is composed of infinite sheets. 

Van Orman JA, Grove TL, Shimizu N (1998) Uranium and thorium diffusion in diopside. Earth Planet Sci Lett 160 505-519... 

Figure 11. The clinopyroxene-liquid partition coefficient for 4+ ions entering the M2-site shown as a function of the ionic radins of the trace cation. Changes in clinopyroxene composition along a solid solntion lead to small changes in the dimensions of M2 (ro Jw 2>), which can lead in turn to changes in the relative fractionation between 4+ ions of similar ioiuc radii, such as and Th" (shown as vertical lines). We contrast the partitioning behavior of a diopside-rich clinopyroxene = 1 044 A) and a...

The denotes molar, rather than weight fraction, partition coefficient. The X terms denote the cation molar fractions of Ca, Al and Mg, while the X terms denote the molar fraction of diopside and enstatite components in clinopyroxene. Note that this expression contains no explicit P-f dependence. 

Umsov VS, Dudnikova VB (1998) The trace component trapping effect experimental evidence, theoretical interpretation, and geochemical applications. Geochim Cosmochim Acta 62 1233-1240 Van Orman JA, Grove TL, Shimizu N (1998) Uranium and thorium diffusion in diopside. Earth Planet Sci Lett 160 505-519... 

The cations located between the chains hold them together. Some pyroxenes are diopside (CaMgSi206), hendenbergite (Ca(Fe,Mg)Si206), and spodumene (LiAlSi206). 

Fig. 1. An indicator mineral plume consisting of Cr-diopsides glacially dispersed from the Thompson Nickel Belt in Manitoba, Canada, detected in 20 litre till samples at a 30-km spacing (Thorleifson et al. 1994 Thorleifson Matile 1997). 

Chromian clinochlore, 6 471t Chromian diopside, 6 471t Chromian garnet, 6 47 It Chromian geikielite, 6 47 It Chromic acetate, molecular formula, properties, and uses, 6 563t Chromic acetylacetonate, molecular... 

Find the projection y of the rock composition x given in weight percent in Table 2.2 into the diopside-olivine-silica triangular diagram of Walker et al. (1979). This diagram uses coordinates given by ... 

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