Olivine and pyroxene in the Orgueil meteorite

Petrographic and oxygen-isotopic study of refractory forsterites from R-chondrite Dar al Gani 013 (R3.5–6), unequilibrated ordinary and carbonaceous chondrites

“…Reid et al (1970) and Fuchs et al (1973) concluded that these forsterite grains represent condensates from the solar nebula (Grossman and Olsen, 1974;Olsen and Grossman, 1978;Steele, 1986bSteele, , 1989Weinbruch et al, 1993Weinbruch et al, , 2000Klerner, 2001) and that melt inclusions in them are also direct condensates (Fuchs et al, 1973;Yoneda and Grossman, 1995). Melt condensates may form when the equilibrium condensation temperatures of mineral assemblages exceed their solidus temperatures.…”

“…Such forsterites should have ϳ0.2 mol% fayalite and MnO and NiO contents in the ppm range (Palme and Fegley, 1990). Reid et al (1970) and Fuchs et al (1973) were the first to describe isolated FeO-poor, refractory forsterite grains from carbonaceous chondrites (e.g., Fig. 1A).…”

The oxygen-isotope composition of chondrules and isolated forsterite and olivine grains from the Tagish Lake carbonaceous chondrite

“…Refractory forsterite is proposed to have formed as a nebular condensate or as a product of crystallization within Fe-poor chondrules (Reid et al, 1970;Fuchs et al, 1973;Grossman and Olsen, 1974;Olsen and Grossman, 1978;Richardson and McSween, 1978;Steele, 1986b;Jones, 1992;Weinbruch et al, 1993Weinbruch et al, , 2000Jones et al, 2000Jones et al, , 2004Pack et al, 2004Pack et al, , 2005Jones and Carey, 2006). If refractory forsterite is a nebular condensate, its oxygen-isotope composition should represent equilibrium with nebular values at that time or location.…”

Comparing Wild 2 particles to chondrites and IDPs

“…3. Composition ranges of olivine (Fa) in grains from nine Wild 2 particles, compared with those for chondritic IDPs (Zolensky and Barrett 1994) and primitive chondrite matrix olivine (Greshake 1997;Brearley 1993;Reid et al 1970;Kerridge and MacDougal 1976;Krot et al 1995;Fuchs et al 1973;Nagahara 1984;Matsunami et al 1990). Vertical scale is number of analyses normalized to a total of 1. diffraction (SXRD) or selected area electron diffraction (SAED) patterns reveal low-calcium pyroxenes to be orthoenstatite, requiring slow cooling, but in the majority of cases we have only EDX analyses and are not certain whether we have ortho-or clinopyroxene.…”