Geology Reference
In-Depth Information
CV3 chondrite
735.9 g
Found December 14, 1984
9.0 × 8.0 × 6.5 cm
Weathering = Ae
The CV chondrites contain 1-mm-sized chondrules that are mainly por-
phyritic. They have a high matrix to chondrule ratio, as well as abundant
CAi and AoA contents. There are also abundant salite-hedenbergite-
andradite nodules present. The CV chondrites have been subdivided into
reduced and oxidized groups. The oxidized subgroup contains two kinds
of secondary alteration: magnetite, fayalite, nepheline, or sodalite (A)
or phyllosilicates, magnetite, fayalite, sulfide or hedenbergite (B). The
reduced subgroup is unaltered.
Plate 19
MiNERALogy
SigNiFiCANCE
Chondrules up to ~2 mm in diameter, clasts, and inclusions
up to ~4 mm in maximum dimension are distributed in a
pristine matrix consisting of (at least) abundant minute
olivine plates of Fa
45-50
composition, troilite, and awaruite.
The olivine in chondrules, and larger matrix grains, has
a wide range of composition, from Fa
0-30
, but most are
Fa
0-10
. Pyroxene grains having a composition close to Wo
1
En
97
Fs
2
were found. Fine- and coarse-grained refractory
inclusions are present, including large Type A with
gehlenitic melilite, spinel, and Ti-rich fassaitic pyroxene.
ALH 84028 contains fayalite-rich regions that replace
sulfide and oxide nodules in the matrix and portions of
chondrules. A satisfactory explanation for these Fa-rich
regions has been elusive but essentially opens the age-old
questions of whether they formed in a nebular process or
later in parent body processes. This sample will continue
to help address this question.
References [109-116]
