Return to course homepage.
Handspecimen of Murchison (CM2 chondrite).
In this agglomeratic rock, chondrules and
CAIs (the lighter objects) are set in dark,
carbon- and water-rich fine-grained matrix.
Orange areas were stained by terrestrial weathering.
Metal (white) and sulfide (yellow) rim around
a large chondrule in the Yafa (H5) chondrite,
viewed in reflected light. Image is 2.5 mm wide.
Typical area of a metamorphosed ordinary chondrite (St. Robert H5 chondrite)
seen on a polished surface in reflected light. Metal and sulfide appears bright, silicates grey,
and cracks black. Metamorphism has not fully obscured the original chondrule-matrix texture.
Cut face of SNC meteorite EETA79001, a basaltic shergottite. Impact melt glass (dark) was
produced during the impact event which lofted the rock off its parent body. Small amounts of gas
from an atmosphere on the parent body were trapped in the melt glass and provide compelling
evidence that this and other SNC meteorites originated on Mars. Note the overall grey or tan color
of the specimen, which is unlike the orange-tinted and probably weathered materials seen in
spacecraft images of the martian surface.
Cut and polished face of a sample of the Millbillillie eucrite, a basaltic achondrite of the HED family
probably derived from asteroid 4-Vesta. White areas are plagioclase, and grey areas are clinopyroxene.
The reddish rind was produced by terrestrial weathering of the original fusion crusted surface.
Cut and polished face of the DAG 844 howardite, a polymict breccia of the HED family consisting mainly
of eucrite and diogenite (green & brown-colored orthopyroxene) clasts. Of all meteorites, howardites best
match the overall mineralogy of the surface of asteroid 4-Vesta. The specimen shown above is 4.5 x 3 cm across.
Slice of the DAG 485 ureilite. Ureilites consist chiefly of millimeter-sized olivine crystals
(visible as brownish-green areas in the image), together with a C-rich groundmass and
smaller amounts of pyroxene (mainly pigeonite). No scale was given for the image
above, but I'd guess the sample is ~10 cm across.
Specimen of the Sikhote-Alin (IIAB) iron meteorite,
showing well developed regmaglypts. A shower of
fireballs produced hundreds of impact holes and thousands
of individual rocks.
Cut and etched surface of Gibeon (IVA), showing
Willamette iron meteorite (IIIAB), which at 15 tons is the largest meteorite
recovered in the U.S. It was found in what is now West Linn.
The large depressions were caused by terrestrial weathering.
Polished slice of the Morristown mesosiderite showing
metal (bright) and silicate (dark). In mesosiderites,
the silicates are dominated by metamorphosed clasts
of basalt, gabbro, plagioclase, and pyroxene, mainly
derived from the upper portion of a differentiated
asteroid. The metal appears to have been derived from
the core of a possibly different asteroid. The specimen
above measures 10 x 7.5 cm across. A somewhat
unusual feature of this particular specimen is the
clumping of metal into clast-like objects.
Cut and polished face of the Mt. Padbury mesosiderite showing clasts of silicate (dark), metal
(light), and mixtures of silicate and metal. Mesosiderites are good examples of polymict breccias,
with clasts having been derived from a variety of lithologies. No scale was given for the above
image, but I'd estimate the sample to be ~25 cm across.
Cut and polished face of a thin slice of the Esquel pallasite. In pallasites, olivine is enclosed by
Fe-Ni metal. The slice above is cut sufficiently thin that olivine is partly transparent. Pallasites
probably formed at the core-mantle boundary of a differentiated asteroid. No scale was given
for the above image, but I'd estimate that the sample is ~5-8 cm across.