Geology Reference
In-Depth Information
CM2 chondrite
14.01 g
Found January 6, 1982
2.5 × 2.5 × 2.5 cm
Weathering = Ae
been at the center of many studies focused on aqueous alteration on their
parent bodies, and on the abundance and species of organic matter. They
are distinguished by their small (~300 micron) chondrules, accretionary
rims around chondrules, common calcium-aluminum-rich inclusions
(CAi), and amoeboid olivine aggregates (AoA), with little to no FeNi
metal and a high matrix (~70%) that contains phyllosilicates, carbonate,
sulfides, and magnetite. Alteration postdates primary features such as
chondrules and CAis, producing some impressive textures in CM2
chondrites.
ALHA81002,0
1cm
OL
OL
100
µ
m
COMP
15.0kV
×
170
100
µ
m
Plate 12
MiNERALogy
SigNiFiCANCE
Chondrules and CAis (40%), fine-grained matrix (35%),
tochilinite/serpentine-rich (25%).
ALH A81002 shows abundant evidence for aqueous
alteration in CM2 chondrites, such as aqueously altered
porphyritic and radial chondrules (left, right; [45]). it
has been a critical sample in defining mineralogic and
textural changes that occur during the alteration.
References [42-50]
