The Jolomba, Angola LL6 chondrite

Abstract

Abstract— Accompanied by loud thunder at about 1.30 pm (local time) on 3 February 1974, a single stone weighing approx. 480 g was seen to fall and was recovered near the Jolomba village, Huambo District, Angola. The stone is strongly brecciated, has dark‐greyish angular fragments within a lighter matrix and does not exhibit any chondritic textures. Jolomba consists of olivine (Fa 31), orthopyroxene (Fs 25), sodic plagioclase (An 11), sulphides (troilite), very scarce nickel‐iron (Ni up to 56%), oxides (chromite and ilmenite) and apatite. Pervasive fracturing of silicates suggests that Jolomba suffered strong brecciation and partial recrystallization. Mineralogy and bulk chemical analysis indicate that Jolomba belongs to the LL group of chondrites (amphoterites). Uniform olivine and pyroxene composition, well‐crystallized plagioclase and textural features in general indicate that Jolomba belongs to the petrologic type 6.

A critical evaluation of oxidation versus reduction during metamorphism of L and LL group chondrites, and implications for asteroid spectroscopy

“…However, analyses of kamacite by Rubin (1990) in many ordinary chondrites indicate that NilFe and ColFe increase with petrologic type, supporting oxidation. Heyse (1978), Patchen (1989), andSighinolfi et al (1991). Regardless of how they are determined, Ol/Px ratios increase with petrologic type, supporting the hypothesis that oxidation increases with progressive metamorphism in Land LL chondrites.…”

The thermal history of equilibrated ordinary chondrites and the relationship between textural maturity and temperature

“…The chemical class is given in each panel and metamorphic type is indicated in parentheses following each meteorite name. (b) Chondrites for which mineral compositions were reported in the literature (Mason, 1963;Bunch et al, 1967;Snetsinger et al, 1967;Lange et al, 1974;Bryan and Kullerud, 1975;Jaques et al, 1975;Paar et al, 1976;Keil et al, 1978a,b;Griffin and Jorgensen, 1979;Gomes and Keil, 1980;Boctor and Kullerud, 1981;Christophe Michel-Lévy, 1981;Hutchison et al, 1981;Klob et al, 1981;Graham et al, 1984;Bevan et al, 1985Bevan et al, , 1988Fredriksson and Wlotzka, 1985;Shima et al, 1986;Rubin, 1990;Sighinolfi et al, 1991;Johnson and Prinz, 1991;Kleinschrot and Okrusch, 1999;…”