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78 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
FIGURE 5.—An Mg-rich olivine and pyroxene chondrule
(shown by arrow in Figure 4), is lined with nickel-iron and
troilite, black. It is intergrown with matrix (lower right) and
with a fragment of a barred "equilibrated" olivine (Fa^)
chondrule (lower left), which is part of a fragment of preexisting
chondrite (shown under arrow in Figure 4). Length
of section, 0.6 mm.
drules (Figure 6), some with Si-Al enriched and only
partly devitrified glass. This glass has approximately
66% SiO2, 21% A12O3, and 8% soda; the
normative composition is again almost albitic with
some quartz and minor corundum and pyroxene.
Shock alterations, including fracturing wavy extinction
and veining (Fredriksson, et al., 1964), are
abundant and the glass may be impact-produced;
however, it would hardly be in equilibrium with
olivine-pyroxene at metamorphic temperatures of
800° to 1000° C.
Olivine: Fa^.o
Pyroxene: Woj s En77 Fs^
Plagioclase: Or5 Ab7S AnJ7
SEGOWLIE
Segowlie perfectly fits the definitions for a crys-
talline chondrite and almost as well for the L6
group. The photomicrograph in Figure 7 shows
individual patches with equigranular, recrystallized
structure, identical to that in the H-chondrite
Andura (Fredriksson, et al., 1975). However, the
grain size varies grossly between the different parts,
i.e., the stone is still a breccia. Thus it seems
unlikely even in this case that the structure is due
to simple metamorphic recrystallization. Some parts
(Figure 8) also show rather well-delineated chondrules,
i.e., a structure more like L5.
Olivine: Fa^.,
Pyroxene: Wo, En78 Fs22; W044
Plagioclase: Or5 Ab77 An18
SULTANPUR
Walker, 1924; Coulson, 1940
Sultanpur has been classified as a black chondrite
and an L6, but both designations are somewhat
questionable. It is more a black chondrite than
Atarra, but not in the same sense as shock products
like Farmington and McKinney (Fredriksson, et al.,
1964; Heymann, 1967). Sultanpur seems rather to
be close to a brecciated (and veined) gray chondrite.
The grain size is much finer and the
chondrules better defined than in the L6 Segowlie;
thus Sultanpur could probably also be an L5,
particularly because the plagioclase does not occur
as clear, well-defined grains. Evidence of shock
effects, e.g., fracturing and undulatory extinction,
in both olivine and pyroxene are common,
however.
Discussion
Bulk and phase compositions, as well as phase
abundances (Tables 1, 2), clearly show the close
relation among these eight meteorites in spite of
their different appearances and classifications. Essentially
only the contents of nickel-iron and troilite
vary significantly (Table 3), while the silicate fractions
are chemically almost identical even in the
obviously fragmentary Mabwe-Khoywa. The silicate
fraction compositions in Table 4 were obtained
by deducting metal, troilite, Fe for ilmenite and
chromite, and Ca for apatite from the bulk analysis.
While normative and modal amounts of pyroxene
are close, both olivine and plagioclase are higher
in the norm, which must be compensated for by